THE FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 254 — 13 February 2014 Editor: Bo Reipurth ([email protected]) List of Contents

The Newsletter Interview ...... 3 My Favorite Object ...... 5 Editor: Bo Reipurth [email protected] Perspective ...... 10

Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers ...... 13 [email protected] Abstracts of Newly Accepted Major Reviews . 54 Technical Assistant: Hsi-Wei Yen Dissertation Abstracts ...... 60 [email protected] New Jobs ...... 61

Editorial Board Meetings ...... 63 Summary of Upcoming Meetings ...... 66 Joao Alves Alan Boss Short Announcements ...... 67 Jerome Bouvier New Books ...... 68 Lee Hartmann Thomas Henning Paul Ho Jes Jorgensen Charles J. Lada Cover Picture Thijs Kouwenhoven Michael R. Meyer This shows the blueshifted outflow cav- Ralph Pudritz ity from the embedded quadruple Class I source Luis Felipe Rodr´ıguez L1551 IRS5 based on Hα and [SII] images obtained Ewine van Dishoeck with the Subaru telescope images. Two short jets, Hans Zinnecker HH 154, are seen to emerge from the source region to the upper left. The outflow cavity has burst The Star Formation Newsletter is a vehicle for through the front of the cloud, exposing the rich fast distribution of information of interest for as- and complex Herbig-Haro shock structures within. tronomers working on star and formation A few faint knots from the HH 30 jet (outside the and molecular clouds. You can submit material field) are visible at the top of the image. The for the following sections: Abstracts of recently field is about 7×8 arcmin, corresponding to about accepted papers (only for papers sent to refereed 0.30×0.35 pc at the assumed distance of 150 pc. journals), Abstracts of recently accepted major re- North is up and east is left. views (not standard conference contributions), Dis- sertation Abstracts (presenting abstracts of new Subaru images: Bo Reipurth Ph.D dissertations), Meetings (announcing meet- Color-composite: Robert Gendler ings broadly of interest to the star and planet for- (http://www.robgendlerastropics.com). mation and early community), New Jobs (advertising jobs specifically aimed towards persons within the areas of the Newsletter), and Short Announcements (where you can inform or re- quest information from the community). Addition- Submitting your abstracts ally, the Newsletter brings short overview articles on objects of special interest, physical processes or Latex macros for submitting abstracts theoretical results, the early solar system, as well and dissertation abstracts (by e-mail to as occasional interviews. [email protected]) are appended to each Call for Abstracts. You can also submit via the Newsletter Archive Newsletter web interface at http://www2.ifa. www.ifa.hawaii.edu/users/reipurth/newsletter.htm hawaii.edu/star-formation/index.cfm

2 in ISM and star formation. Universities wise, besides PKU and its Kavli institute, Nanjing U., Tsinghua U., Beijing Yuefang Wu Normal U., Guangzhou U., Hebei Normal U., Xiangtan in conversation with Bo Reipurth U., Tibet U. have research groups of this field. Very re- cently, Yunnan U. has created and filled leading scholar position of this field. Workshops, conferences, training classes in star formation are held frequently. In 2007, our group held the ”Cross-Straits Workshop on Star Forma- tion” at PKU. Experts gave lectures to nearly 50 young as- tronomers. We also held the ”ISM 2010” meeting with the subject ”The Frontier on Interstellar Medium - 40th An- niversary of the Discovery of CO in ISM” at KIAA/PKU, which had attracted more than one hundred experts and young astronomers world wide. Q: A very influential paper of yours dealt with high veloc- ity molecular outflows from both low- and high-mass young . What were your main conclusions, and do you still work in this area? Q: You have been engaged in studies of star forming re- A: The outflow mass was found to correlate strongly with gions for many . When did you develop this interest? bolometric of the center source. There are also A: I entered the Division at Peking U. (PKU) correlations among the central source luminosity and the about 10 years after I graduated from a 6- university parameters of mechanical luminosity and the force nec- program in 1964. My original major was nuclear physics, essary to drive the outflow. These results suggest that which was interrupted by two years practical work in the the luminosity of the central stellar source determines the ”Four-Clear-Ups” in the countryside for new faculty. Be- mass, momentum and energy of the outflows. Although fore the end of this practice the Cultural Revolution began the radiation pressure of the central sources is not enough and lasted till the early 70’s. These activities took a lot of to drive the outflows, the driving mechanism should be time away from my science career but gave me a chance stellar but non-radiative. This is a key to understand the to contemplate my academic interests. In the 70’s the physical processes of star formation, because the outflow- education/research system had gradually recovered. Sev- driving mechanism is an essential distinction in the prin- eral colleagues and I began some research in interstellar cipal models of massive star formation. We also found molecules and the ISM. Inspired by the series of papers that these correlations exist in a wide range of bolometric −1 6 on energetics by Evans et al. we began to luminosity from 10 to 10 L⊙, indicating similarities in examine the heating and cooling mechanisms of interstel- the driving mechanism between low- and high-mass out- lar gas and dust. Our first target was W40 (S64). At that flows. It suggests that high-mass stars form in a similar time we just used the published CO and infrared data by way as low-mass stars. However, there are also differences Zeilik & Lada. Later on we studied this interesting object between high- and low-mass outflows. For example, high- in lines of CO (1-0) (3-2) and 13CO (2-1) (3-2). A weak mass outflows are generally less collimated than low-mass outflow and the discrepancy of the core peak and the Hii outflows. This difference may be due to the environment region were revealed. Last year, Pirogov et al. found evi- and evolutionary states of the central sources. We are still dence of interaction between the ionized and neutral ma- continuing with this investigation of outflows. We have ex- terials and possible triggers of star formation around this tended our study of massive star feed back to the phases ii source. And Mallick et al. revealed an embedded cluster later than UC H regions. at the Herschel filament junction. A comparison of earlier Q: So outflows offer evidence to support the model and new results of this source witnesses the development for high-mass star formation. How about inflow? Is this of star formation studies during the recent three decades. also similar in the formation of low- and high- mass stars? Q: You were one of the pioneers in opening up the subject of star formation in China. What is the status today? A: Yes, inflow is also critical to distinguish models of A: In the early 80’s there were only few groups and about a spherical infall, disk accretion and mergers by less massive dozen researchers working on star formation. Now Purple stellar objects. Since 2003 several surveys of inflow mo- Mountain Observatory (PMO), National Astronomical ob- tion in high-mass star forming regions have been carried servatories, Shanghai Observatory, Yunnan Observatory, out. We made a mapping survey of two group samples and Xinjiang Observatory all have science teams working with different evolution phases, one group consisting of

3 UCHii regions and the other UCHii precursors (UCHiiP), telescopes are being built in our country. Besides the al- younger than the former. Seventeen sources were detected ready constructed 65m in Shanghai, projects of the Dome with inflow signatures, known as ”blue profile”. The ex- A Terahertz Explorer-5 (DATE5) and 110m radio tele- cess of blue over red profiles is 17% for the UCHiiP and scope in Qitai (QTT) are in progress. The Five-Hundred- 58% for UCHii, suggesting that the inflows are occurring Meter Aperture Spherical Radio Telescope (FAST) at Da- more frequently in regions with stronger radiation. This wodang is expected to see first light in two years. China is consistent with the disk-accretion model and does not also joined Herschel and SKA. Besides, our country has favor the other two models. Another difference is that the also begun to help in operating telescopes and sharing the blue excess in the low-mass sources does not clearly show time. Such collaboration for medium and large optical- such an evolutionary trend. The reasons need to be ex- infrared telescopes was begun in 2011. And a similar plored but in general, it shows that the infall motion is still project for sub-millimeter telescopes is in discussion now. ongoing during the UCHii phase. To test these single-dish I believe that these new facilities and projects will help us results we investigated infall candidates in high-mass cores to build a bright academic future. Domestic and interna- using high resolution data. So far UCHii regions G19.61- tional co-operations will be further developed. 0.23, G9.62+0.19E, NGC7538 IRS1, G10.6-0.4, G34.26- Q: Most recently, you have been engaged in studies of ii 0.15 and UCH P cores JCMT18354, W3-SE, G9.62+0.19F, Planck cold dust clumps. What have you found? G23.44-0.18, G8.68-0.37 were studied. A series of results have been obtained but we have found no significant dif- A: An unprecedented result is the close consistency of the ference to the single dish observations. systemic velocities in the three CO isotopologue lines. Dis- tributions of physical parameters such as column density, Q: Your main research focus in recent years has been the optical depth and velocity dispersion with Galactic radius study of cloud cores. What facilities do you use, and are and altitude from the Galactic plane were obtained. The new ones being built in China? excitation-temperature distribution is peaked at 9-10 K. A: To find early cores and examine the initial conditions Line widths are smaller than in samples I-IV (mentioned of star formation, we have searched a number of samples earlier) and IRDCs, EGOs. Generally they are quiet, cold including IRAS UCHii candidates (I), weak and red IRAS and without developed star-forming activities. However (II), sources with H2O masers but without UCHii region the emission regions can be dense and isolated, or diffuse (III) or with CH3OH masers (IV). Results show that group and extended. Filaments are most common among their II tends to have a small column density and line FWHM, morphologies. Most of the cores are starless. CO deple- while group IV has the largest for both the parameters as a tion and conversion (CO-to-H2) were found to be strongly whole. It is interesting that core peaks seem always sepa- (anti-)correlated with gas and dust parameters. Planck rated from the associated YSOs. With the beam size used Clumps are useful in revealing early phases of star for- in the survey, cores containing YSOs were excluded from mation and dense core formation, and even the transition starless cores. However, observations with higher resolu- from HI to H2. tion of these cores show their peaks are separated from the Q: You have been teaching many generations of astronomers YSOs. For example, in source JCMT18354, IRS1a is in at Peking University. Have you seen changes in the job the core measured with Effelsberg/JCMT but separated prospects of all these young people? from the peak of the core observed with SMA. Such situ- ations are very common in massive cores. Are these cores A: Almost all our students who graduated in the 80’s really starless? How do they form? Are they going to form and 90’s are now chief scientists or senior astronomers in stars? What is the difference between them and nearby Astronomical Observatories or Institutes. Some of them cold starless cores? Early cores such as G28.34+0.06 P1 hold leadership roles. I am also impressed by the talent has been examined with high resolution. Hierarchical frag- moving into our field, some even from oil industry and mentation and jet-like outflows were found. All the equip- medicine. Now they are studying astronomy diligently ment that we have used was accessed through interna- and successfully. One change of job prospects I sense is tional collaborations. Our group has been a heavy user that promotions seem to become faster. Take the 2003 of the PMO 13.7m and KOSMA 3m of Cologne U., the graduates (03G) as an example: two of them have been re- latter has recently been moved to Tibet. We also fre- cruited by the ”Thousand Youth Talents Program”. One quently use the two 25m dishes of Shanghai and Xiajiang of their classmates became an assistant professor at Duke observatory. Among the international facilities we have U. One 03G student from abroad also told me ”now it used are MWO 5m, NRAO 12m, FCRAO 14m, Effels- seems that astronomy positions are easier to find than in berg 100m, JCMT 15m, IRAM 30m, CSO 10m, SMA, other fields”. We need to let more people know that there CARMA, VLA/JVLA and GBT 100m. These telescopes is stronger support for astronomy today in China than are critical for our group’s research. Yes, a number of new ever and we need more astronomers in the future, includ- ing from abroad.

4 My Favorite Object Rainer K¨ohler

Introduction

Every astronomer knows (or at least should know) the sys- tem T Tauri, since it gave its name to the whole class of Figure 1: T Tauri (the orange star in the center) and ′ ′ young stars. Over the centuries, better observational tech- Hind’s . The field of view is 16 × 16 . North is niques enhanced our knowledge of the system, often only up and east to the left. (Image by T. A. Rector/Univer- to show that it is more complex than previously thought. sity of Alaska Anchorage, H. Schweiker/WIYN and With every new discovery made, it turned out to be more NOAO/AURA/NSF) prototypical than typical for T Tauri stars. T Tauri was discovered in November 1852 by John Russell Hind (Hind 1864). Using a 7-inch refractor (quite a large century as it is now, it might not have been discovered telescope at the time), he noticed a variable nebula in Tau- so early, and the class of T Tauri stars might have been rus (now known as Hind’s nebula, NGC 1555 or HH 155). named differently. In a side note, he mentioned that the star at the edge of It was soon suggested that T Tauri stars are solar-type the nebula is also variable. A few years later, this star was stars in the early stages of formation (Ambartsumian 1947). named T Tauri, because it was the third dis- Since that time, this has been generally accepted and be- covered in (the first variable star in a came essentially the definition of the class (Herbig 1962). is denoted R, the second S, and so on). As the prototype and one of the brightest members of the Between 1867 and 1916, the visual brightness of T Tauri class, T Tauri has been and still is observed frequently, fluctuated randomly between 9.6 mag and 13.6 mag on time and many publications have been written about it. At scales as short as a month (Lozinskii 1949; Beck & Simon the time of this writing, Simbad lists 1122 references (and 2001). Beck & Simon (2001) find that variable it does not even include anything before 1895). I read along the line of sight is the most likely explanation for about 1% of those papers and skimmed through another the observed fluctuation. In 1918, this kind of variability 2%, so I want to apologize in advance if I missed anything stopped abruptly, except for brief dimming events in 1925 important. and 1931. Between 1986 and 2003, T Tauri showed only low-level variability with an amplitude of 0.22 mag in V (Grankin et al. 2007). A binary. . . In 1945, Alfred H. Joy proposed the new class of “T Tauri In 1981, Mel Dyck et al. observed T Tauri with the new ob- variable stars” based on their similar physical characteris- serving technique of infrared speckle-interferometry (Dyck tics (Joy 1945). The name was chosen because T Tauri was 1982). They were quite surprised to find that it is a bi- the best known member of the group, one of the brightest, nary. Today, it is generally accepted that most T Tauri and its spectrum was also representative for the group. If stars are multiple systems, but back then, T Tauri lived the brightness of T Tauri had been as stable in the 19th up to its role as prototype. Dyck et al. had only an InSb-

5 photometer that scanned the target in north-south direc- tion. Luckily for them, T Tau N and S, as the two stars are called, are oriented almost exactly in that direction, with a separation of about 0.6′′. They observed at three differ- ent wavelengths (2.2 µm, 3.8 µm, and 4.8 µm) and noted that the colors of the two stars are very different. Bertout (1983) suggested that T Tau S is a of 2 to 3M⊙, obscured by 8 to 19 mag of visual extinction. T Tau S is so red that it has never been detected at visual wavelengths. Stapelfeldt et al. (1998) found no of it in HST-images with a limiting of V = 19.6mag. Therefore, it became the prototype for the so-called infrared companions (IRCs), companions to young stars that are much brighter in the infrared than at optical wavelengths (Koresko et al. 1997). The most likely explanation for this phenomenon is that IRCs are normal young stars hidden behind circumstellar dust, e.g. an seen edge-on.

. . . or a triple

In the 1980s and 1990s, bigger telescopes and better in- Figure 2: Image of the T Tau system taken with struments were built. With the Keck telescope and the VLT/NACO in the Ks filter on 2008 February 1, shown good seeing on Mauna Kea, T Tau N and S could be re- with a logarithmic scale. solved with direct imaging, without any special methods to enhance the spatial resolution. Chris Koresko used the opportunity and applied speckle interferometry to T Tau S the radio signal, since the southern radio source was never alone. It turned out that T Tau S is also a binary, with a resolved into a binary. Therefore, the motion of the radio separation of 53 milli-arcsec at the time (Koresko 2000). source T Tau Sb had to be derived from precise This makes T Tauri a triple system consisting of T Tau N, relative to T Tau N. T Tau Sa, and T Tau Sb. The interest in the orbit of T Tau S was met by new adap- The second resolved observation of T Tau Sa/Sb (K¨ohler tive optics systems at large telescopes, which allowed to et al. 2000) showed that the position angle had changed take resolved infrared images of all three components in by 28◦ in only two years. It was clear that this binary has the system (Fig. 2). With these instruments, T Tauri was a rather short period, which will allow to determine its observed quite frequently and a lot of astrometric measure- orbit within a reasonable time span (less than the lifetime ments were collected (Duchˆene et al. 2002, 2005; Furlan of its observers). et al. 2003; Beck et al. 2004; Mayama et al. 2006; Schaefer However, Loinard et al. (2003) claimed that T Tau Sb et al. 2006; K¨ohler et al. 2008; K¨ohler 2008; Schaefer et had suffered an ejection during the close encounter with al. 2013, 2014). The latest measurements and orbit deter- Sa around 1996. According to their data, the orbit of mination were presented at the & VI T Tau Sb had changed dramatically. T Tau Sb might conference (Fig. 3). They show no sign of T Tau Sb escap- even be leaving the system altogether. This would be the ing from the system or even being on a highly eccentric first time such an event had been observed, and caused orbit. The most likely explanation is that the radio source a lot of interest in the orbit of T Tau Sb. The observa- is connected with, but not identical to the infrared source tions of Loinard et al. were carried out with the VLA at (Johnston et al. 2004a,b; Loinard et al. 2007a). 2 and 3.5 cm wavelength. In the radio regime, T Tau is A nice result of the precise astrometry achieved with radio a double source, separated by about 0.7′′ in north-south observations, however, is the measurement of the distance direction. It is clear that the northern radio source is the of the T Tauri system, which is 146.7 ± 0.6pc (Loinard star T Tau N. The southern radio source was coincident et al. 2007b). This is one of the most precisely known within the errors with the position of T Tau Sb in an in- distances to any , since most of them were frared image taken almost simultaneously. This led to the too far away for the Hipparcos . conclusion that the radio source is identical to T Tau Sb. T Tau Sa does apparently not contribute significantly to The presence of the third component gives us the rare op-

6 Figure 3: Orbital motion for T Tau Sa-Sb. Black circles are NIRC2 measurements. Gray circles are measurements with other instruments. Overplotted is the best fit orbit with a period of 28yr (from Schaefer et al. 2013) portunity to use T Tau N as astrometric reference and de- Figure 4: False-color continuum-subtracted image of the termine the absolute motion of T Tau Sa and Sb around 2.12 µm quadrupole line of molecular in T Tau. their center of mass (Duchˆene et al. 2006; K¨ohler et al. The immediate area of the stars is blanked out to avoid 2008; K¨ohler 2008). This way, we can get an estimate distracting artifacts. Note the arcs to the northwest of for the mass ratio of Sa and Sb. Together with the sum T Tau N and west of T Tau S. (from Herbst et al. 2007) of their resulting from the orbit, we can calculate individual masses for the two stars. With the latest or- bit solution by Schaefer et al. (2013), we find M = Sa a few arcseconds, which was later named Burnham’s neb- 2.3 ± 0.3 M⊙ and M = 0.4 ± 0.2 M⊙. The mass of Sb ula (HH 255). T Tauri also drives the giant bipolar flow T Tau N was estimated to be about 2 M⊙, based on its HH 355, which extends 38 arcmin in roughly north-south spectral energy distribution (Loinard et al. 2007b). This direction (Reipurth et al. 1997). Using high-resolution, means that T Tau Sa is the most massive star in the triple, long-slit spectra of the nebulosity around T Tauri, B¨ohm although it is invisible in the optical. & Solf (1994) identified two outflow systems, one oriented T Tau Sb appears to be a “normal” low-mass pre-main- southeast-northwest, and a second flow in east-west di- sequence star hidden behind a thick layer of extinction rection. Herbst et al. (2007) suggest that the east-west (AV ≈ 15mag, Duchˆene et al. 2005). T Tau Sa is more outflow arises from T Tau S, although they could not de- massive, but also more obscured, which makes it the proto- termine which of the two components produces it (Fig. 4). typical IRC in the system. Reipurth (2000) suggested that Gustafsson et al. (2010) used high-spatial-resolution, inte- T Tau N appears unobscured because it was ejected into gral-field spectroscopy to study the messy environment a distant bound orbit and moved out of the dense cloud within 300 AU (2′′) of T Tauri. By comparing their images core, while T Tau Sa/Sb moved deeper into the cloud. with the data of Herbst et al. (2007), they could measure for some of the blobs. This way, they iden- Outflows. . . tified yet another outflow moving away from T Tau S in south-west direction. The driving source for this outflow As a typical classical T Tauri star, T Tauri is surrounded appears to be T Tau Sb, while Gustafsson et al. argue that by a number of nebulous patches. Hind’s nebula is located the southeast-northwest outflow is coming from T Tau Sa. about 35′′ to the west. Burnham (1890) discovered a faint By exclusion and because of the (lack of) proper motions, and diffuse nebula surrounding T Tauri with a diameter of they assign the east-west outflow to T Tau N. In this pic-

7 ture, the east-west outflow is moving at an angle of only never been seen at optical wavelengths. ◦ ∼ 20 to the line of sight. Its location due west of T Tau S Duchˆene et al. suggest that T Tau Sa has a circumstellar is only a coincidence. disk seen almost, but not exactly edge-on. The light we re- Our confusion about the driving sources of the jets is at ceive is a combination of and inner disk emission. least partly caused by the significant motion of the stars The IR spectrum shows no photospheric features, which between the time a blob is ejected into an outflow and the could be explained by a spectral type between late B and time we observe it. Together with the uncertainty in the mid-F, in line with the dynamical mass determination. motion of both the stars and the gas, it is difficult to find In an attempt to resolve the mystery around the disks the proverbial smoking gun. in the T Tauri system, Ratzka et al. (2009) observed it with even higher spatial resolution, using the mid-infrared . . . and disks interferometric instrument MIDI at the VLTI. To model their data, they used a sophisticated disk model based on Where there are outflows from young stars, there are usu- the radiative transfer code MC3D. The results for T Tau N ally also circumstellar disks. Akeson et al. (1998) ob- confirm the earlier measurements: A circumstellar disk served T Tauri with the BIMA millimeter array at λ = seen almost face-on with an outer radius of 80 AU (smaller 3 mm and found dust emission centered at the position of than the projected separation between T Tau N and S). T Tau N. They interpreted the emission as coming from The binary T Tau S is well-resolved interferometrically, a circumstellar disk and estimated its parameters by fit- but not photometrically, which makes the interpretation ting a flat-disk model. The outer radius was estimated of the data more difficult. To disentangle the contribution to be about 40 AU, smaller than the projected separation of T Tau Sa and Sb to the photometric and correlated between T Tau N and S. This means that the disk around flux, they assumed a model of T Tau Sb that describes it T Tau N does not cause the strong extinction in the line as a normal low-mass T Tauri star behind an absorbing of sight to T Tau S. Akeson et al. did not detect emis- screen. It is surrounded by a circumstellar disk seen al- sion at the position of T Tau S, which rules out a greater most face-on, truncated by the close neighbor T Tau Sa. circumstellar mass around T Tau S. With this model, the interferometric data indicate a struc- ture elongated in north-south direction, probably a cir- Walter et al. (2003) mapped the environment of T Tauri cumstellar disk seen almost edge-on. Therefore, T Tau Sa with long-slit far-UV spectra. They found extended H2 ′′ might again be seen as the driving source for an east-west emission up to 10 from the stars. A dip in the bright- outflow system. ness profile at the location of T Tau S indicates that 85% of the fluorescing gas is behind T Tau S. They concluded Despite the puzzling complexity of the T Tauri system that T Tau S is not obscured by a large disk surrounding (see Fig. 5), it is clear that the disks of the three stars are T Tau N. Rather, we might have just the opposite situ- misaligned with respect to each other. The jury is still ation, and the strong variability of T Tau N before 1917 out on the orbits, but there is no obvious alignment of the might have been caused by obscuration from circumstellar orbits with one of the disks either. material around T Tau S. Duchˆene et al. (2005) studied the system with high spa- Still a variable star tial and spectral resolution in the infrared. From their IR photometry of T Tau Sb, they derive an extinction of Since 1917, the brightness of T Tauri in the optical has AV ≈ 15 mag. They explain it with the structure seen in shown only small variations. The same is true for the absorption by Walter et al. (2003), which means that it infrared brightness of T Tau N since the beginning of in- extends in front of T Tau Sa as well. This implies that it frared observations in the 1980s. However, T Tau S has is too large to be a circumstellar disk, but it could be a shown large variations in the near- and mid-infrared. It is circumbinary envelope or disk. not easy to find the culprit in the Sa/Sb binary, since many In the spectra of T Tau Sa, Duchˆene et al. found ab- of the observations did not resolve the pair, but van Boekel sorption lines of CO. Since the absorption lines are not et al. (2010) argue that the variability is mostly caused by detected in the spectrum of T Tau Sb, and since the de- the IRC T Tau Sa. Variable extinction, variable accretion, rived gas temperature is ∼ 390K, the gas has to be lo- or a combination of both have been proposed as reason for cated within a few AU of T Tau Sa. Furthermore, the the variability (Ghez et al. 1991; Beck et al. 2001; Beck column density of CO gas corresponds to an extinction et al. 2004; van Boekel et al. 2010). However, van Boekel et al. observed T Tauri through a narrow-band filter at of AV ≈ 90 mag (assuming an interstellar-like gas-to-dust ratio, although the ratio might be very different in the 12.81 µm and witnessed a change in the N/S brightness circumstellar material). This explains why T Tau Sa has ratio by 26% in four days. They argue that an absorbing screen would have to move with ∼ 210 km/s to uncover

8 the emitting region within four days. An object moving so fast would not stay in the system very long. Rather, van Boekel et al. suggest that at least the short-term vari- ations are caused by variable accretion, which may have been induced by the periastron passage of T Tau Sb in 1995. Since T Tau Sb has passed its apastron in 2009, T Tau Sb should have become fainter and less variable by now. However, there is no sign of it getting fainter, although there are not enough observations to say much about its variability (van Boekel, Schaefer, priv. comm.).

The future of T Tauri

Walter et al. (2003) nicely summarized the situation: “T Tauri continues to confound and perplex, but better ob- servational data are yielding new insights.” This has con- tinued in the last 10 years, and will probably continue in the future. Therefore, T Tauri will remain among the first targets to observe when a new telescope or instrument is commissioned. In the near future, we can hope to find out how large the disks around the stars really are and how they are oriented. We might even be able to figure out how Figure 5: Sketch of our current knowledge of the disks and many outflows there are and identify their sources. In the stars in the T Tauri system. T Tau N is surrounded by a not-so-near future (but still within my lifetime, if nothing large disk seen almost face-on. The disk around T Tau Sb bad happens), we will witness the next periastron passage is also seen almost face-on, but it is truncated by its close of T Tau Sb and see whether it disturbs the accretion onto neighbor T Tau Sa. The disk around T Tau Sa is trun- T Tau Sa. Unfortunately, following the orbit of T Tau S cated and seen nearly edge-on, causing the large amount around N will require a few hundred years, and only fu- of extinction. Both T Tau Sa and Sb are surrounded by ture generations can tell whether the strong variability of a circumbinary envelope or disk, which is responsible for T Tauri in the optical will occur again when T Tau N and 15 mag of visual extinction. The green lines show the or- S have completed one orbit around each other. bits of T Tau Sa and Sb around their common center of mass, and their orbit around T Tau N. The latter orbit References: has to be regarded as uncertain, since the position angle ◦ Akeson, R. L., Koerner, D. W., Jensen, E. L. N. 1998, ApJ, 505, 358 of T Tau S has changed by only about 10 since its dis- Ambartsumian, J. A. 1947, and (Ere- covery. Finally, the green star shows the common center van: Acad. Sci. Armenian SSR) of mass of T Tau N, Sa, and Sb. Beck, T. L. & Simon, M. 2001, AJ, 122, 413 Beck, T. L., et al. 2001, ApJ, 551, 1031 Beck, T. L., et al. 2004, ApJ, 614, 235 Bertout, C. 1983, A&A, 126, L1 B¨ohm, K.-H. & Solf, J. 1994, ApJ, 430, 277 K¨ohler, R., et al. 2008, A&A 482, 929 Burnham, S. W. 1890, MNRAS, 51, 94 Koresko, C. D., Herbst, T. M., Leinert, Ch. 1997, ApJ, 480, 741 Duchˆene, G., Ghez, A. M., & McCabe, C. 2002, ApJ, 568, 771 Koresko, C. D. 2000, ApJ, 531, L147 Duchˆene, G., et al. 2005, ApJ, 628, 832 Loinard, L., Rodr´ıguez, L. F., Rodr´ıguez, M. I. 2003, ApJ, 587, L47 Duchˆene, G., et al. 2006, A&A, 457, L9 Loinard, L., et al. 2007a, ApJ, 657, 916 Dyck, H. M., Simon, T., Zuckerman, B. 1982, ApJ, 255, L103 Loinard, L., et al. 2007b, ApJ, 671, 546 Furlan, E., et al. 2003, ApJ, 596, L87 Lozinskii, A. M. 1949, Perem. Zvezdy, 7, 76. A translation is avail- Ghez, A. M., et al. 1991, AJ, 102, 2066 able at http://www.ess.sunysb.edu/2001aj/beck01.html Grankin, K. N., et al. 2007, A&A, 461, 183 Mayama, S., et al. 2006, PASJ, 58, 375 Herbig, G. H. 1962, Adv. Astr. Astrophys., 1, 47 Reipurth, B., Bally, J., Devine, D. 1997, AJ, 114, 2708 Herbst, T. M., et al. 2007, AJ, 134, 359 Reipurth, B. 2000, AJ, 120, 3177 Hind, J. R. 1864, MNRAS, 24, 65 Schaefer, G. H., et al. 2006, AJ, 132, 2618 Johnston, K. J., et al. 2004a, AJ, 128, 822 Schaefer, G. H., Prato, L., Simon, M., Patience, J. 2013, in: “Proto- Johnston, K. J., et al. 2004b, ApJ, 604, L65 stars and Planets VI”, Heidelberg, July 15-20, 2013. Poster #1K076 Joy, A. H. 1945, ApJ, 102, 168 Schaefer, G. H., et al. 2014, submitted to AJ K¨ohler, R., Kasper, M. E., Herbst, T. M. 2000, In: “The Formation Stapelfeldt, K. R., et al. 1998, ApJ, 508, 736 of Binary Stars (Poster Papers)”, eds. Reipurth, B. and Zinnecker, van Boekel, R., et al. 2010, A&A, 517, A16 H., p. 63 Walter, F. M., et al. 2003, AJ, 126, 3076 K¨ohler, R. 2008, Journal of Physics: Conf. Ser., Vol. 131, 012028.

9 regions of planetary systems, encompassing the habitable zone, has long suffered from a lack of instrumentation with Perspective high contrast capabilities and high angular resolution. Thirty years after their discovery by IRAS, we know that Exozodiacal dust about 20% of nearby solar-type stars are surrounded by an Jean-Charles Augereau optically thin, gas-poor disk of cold debris according to our most recent Herschel statistics (Eiroa et al. 2013). These cold disks reveal large amounts of short-lived micron-sized grains whose existence at such advanced ages (several hun- dred million years to billions of years) points to the pres- ence of large reservoirs of mass in the form of asteroids and comets. In most cases, the collisional erosion of a small population like the Kuiper belt is sufficient to explain the measured infrared and (sub-)millimeter emissions. A new generation of sophisticated models (e.g. Kral, Th´ebault & Charnoz 2013) is now able to handle the collisions between bodies of all sizes and the overall dynamics of a . The knowledge and the modeling of cold debris disks is reaching maturity, which is not the case for exo- zodiacal dust disks.

The hot dust in the inner regions of extrasolar planetary systems, within a few astronomical units from a star, is known as exozodiacal dust, or exozodi, reflecting the similarity with the Solar System’s zodiacal cloud. Histor- ically, the study of exozodiacal dust was motivated by the preparation of space missions aiming to search for extra- solar planets in the so-called habitable zone. Because of its potential ability to complicate the detection of planets, the identification and characterization of exozodiacal dust appeared essential to the space agencies as a preliminary step on the road leading to the detection of other . Since then, the study of exozodis has become a rapidly emerging theme due to its connection to the general dy- namical evolution of planetary systems, in particular in the innermost potentially habitable regions. The origin Figure 1: ”Zodiacal Glow Lightens Paranal Sky”, credit: of exozodiacal dust today remains a mystery that is the ESO/Y.Beletsky subject of a growing body of research. From its original status as a potential obstacle to the detection of other Exozodi detection: The inner solar system is filled Earths, the exozodis now appear as a powerful tool to the with dust responsible for the zodiacal light. This dust is study of extrasolar planetary systems. the brightest circumsolar object after the itself in our Debris disks: Exozodiacal dust clouds belong to the own planetary system. It can be seen with the naked eye greater family of debris disks, which refer to populations above the horizon in good conditions (Fig. 1). This cloud of comets and asteroids which produce dust by collisions of fine dust extends continuously from a few astronomical or evaporation, and interact with planets around stars on units (AU) down to a fraction of an AU, where it forms the the . In the literature, the term ”debris F-corona. The density of this dust cloud increases sunward disk” refers mostly to cold dust belts, similar to the Kuiper and peaks close to the sublimation distance of the grains, Belt, located several tens of astronomical units from their around 4 R⊙. Our current knowledge of the zodiacal cloud host star. This bias is a consequence of the availability is biased toward the region around the ’s orbit which of a specific type of observational facility, in particular a has been observed by several infrared space facilities. The great fleet of infrared (IRAS, ISO, Spitzer, Akari, zodiacal dust component close to the Sun, the F-corona, is WISE, Herschel), which detected the coldest dust since the less well known, and has essentially only been observed in early 1980s. The study of exozodiacal dust in the inner the visible and near-IR during total solar eclipses (Kimura

10 & Mann, 1998 for a review). solar-type stars have (hot) exozodis (Absil et al., 2013; Extra-solar analogs to the zodiacal dust have long been Ertel et al., in prep.). This fraction is very similar to suspected, but remained elusive until very recently. The that of solar-type stars with cold debris disks (Eiroa et first resolved detections of exozodis were obtained by high- al. 2013), and we do not see any obvious correlation with precision interferometry at near- and mid-infrared wave- the age the star. The number of exozodis found is proba- lengths using various arrays of telescopes (e.g. Fig. 2): bly an underestimate due to instrumental limitations that restrict the detection of faint excesses (1σ median excess • CHARA: Vega (Absil et al. 2006); τ Ceti (Di Folco uncertainty of ∼ 0.25% of the stellar flux with PIONIER et al. 2007); ζ Aql (Absil et al. 2008); β Leo (Akeson in the H-band), and definitive conclusions about the frac- et al. 2009), tion of stars with warm exozodis require sensitive inter- ferometric surveys in the mid-IR (e.g. with the LBTI and • VLTI: Fomalhaut (Absil et al. 2009); HD 69830 VLTI/MATISSE). Despite these limitations, we can con- and η Corvi (Smith et al. 2009) ; HD 113766 and clude that the presence of exozodiacal dust around nearby HD 172555 (Smith et al. 2012); β Pic (Defr`ere et al. stars is certainly common. 2012), Basic properties of exozodis: We attribute the near- • MMT: β Leo (Stock et al. 2010), IR excesses to dust grains located within the field of view of the interferometers (a few AU for our nearby targets). • IOTA: Vega (Defr`ere et al. 2011), We employ a radiative transfer code for optically thin disks (GRaTer, Augereau et al. 1999 & Lebreton et al. 2012) • Keck Interferometer Nuller: 51 Oph (Stark et al. to fit the near-IR interferometric measurements, comple- 2009a); η Corvi, 2 marginal detections (Millan-Gabet mented with observations gathered from the literature, et al. 2011); Fomalhaut (Menesson et al. 2013). essentially spectro-photometric observations in the near- and mid-IR (e.g. Fig. 3). Our model accounts for the size- dependent sublimation distance. In the most advanced version of the model, it additionally accounts for the fact that the sublimation temperature is not a constant but also depends on the grain size (Lebreton et al. 2013). We compute grids of models on which we apply a statistical (bayesian) inference method to assess the most probable parameters and to estimate uncertainties.

100.000 star

10.000 exozodi

1.000 cold debris disk

Flux [Jy] 0.100

0.010

Figure 2: Detection of an exozodi with near-IR interferom- 0.001 etry: the drop in visibility (V) compared to what would be 1 10 100 Wavelength [µm] expected for an isolated, resolved star, provides a direct measurement of the disk to star flux ratio (here: 1.2%, Figure 3: Example fit to the SED of Tau Ceti (Di Folco Defr`ere et al. 2011) et al. 2007). The flux is in Jy. Note the lack of detectable excess using classical (spectro-)photometry in the mid-IR. Contemporaneous spectro-photometric observations with the (λ = 8–35 µm) revealed copi- ous amount of hot dust around a handful of stars of all We find that the exozodis detected with near-IR interfer- ages (e.g. Beichman et al. 2005; Chen and al. 2006; Lisse ometry are all composed of submicron-sized grains much et al. 2007, Olofsson et al. 2012). smaller than the blow-out size. These are carbon-rich and tend to accumulate next to the sublimation region, typi- Our systematic near-IR interferometric surveys with the cally 0.1–0.5 AU for an A-type star like Vega, and 0.01– CHARA/FLUOR (42 stars, K-band) and VLTI/PIONIER 0.02 AU, or a few stellar radii, for a solar-type star like (88 stars, H-band) instruments indicate that 15-20% of τ Ceti. There is a striking comparison between these gen-

11 eral properties with those of the hot zodiacal cloud in the solar system, the F-corona, whose emission spectrum in the near-IR is supposed to be mainly due to carbonaceous material (Mukai & Yamamoto 1979) and that shows a den- sity peak around the sublimation radius (∼ 4 R⊙). Figure 4: A diagram (not to scale) to illustrate the scat- The mysterious origin of exozodis: The total mass tering of planetesimals by an outer planet, that leads to −10 −9 of an exozodi, of the order of 10 –10 M⊕, is equiva- an exchange of angular momentum and the outerward mi- lent to that of an asteroid a few km in radius. The grains gration of that planet. Some particles are scattered into are small and thus essentially unbound due to radiation the inner planetary system, where they interact with the pressure. The disk is also dense enough for collisions to be inner planets. This scattering leads to a flux of material frequent. Therefore, the hot exozodis need to be replen- into the exozodi region (Bonsor et al. 2014, submitted). −9 ished at a rate of the order of 10 M⊕/year. Unlike cold debris disks, in situ replenishment in steady-state by col- lisions between planetesimals does not work for exozodis. of (relatively low-mass) hidden planets. Extrasolar plane- Any local population of planetesimals will not survive long tary systems with exozodis could well prove to be hostile enough to sustain a sufficiently high level of dust. The environments for exo-Earths if the flow of comets is im- sophisticated models developed for cold debris disks are portant, or could instead point to a mechanism that can insufficient to explain exozodis (e.g. Augereau 2009). supply water (essential to the emergence of life on Earth) on rocky planets in the habitable zone. Exozodiacal disks This mystery has motivated several studies which attempt can perhaps highlight the complex, but promising, interac- to understand the origin of the large amounts of exozodi- tion between the star and very small dust grains (depend- acal dust that we detect. In recent years, we have ex- ing on the intensity and topology of the local magnetic plored different dynamical mechanisms. For example, we field) and/or very large solid bodies (evaporation of rocky showed that the occurrence of catastrophic events due to planets). This scientific field is emerging, raising many as- dynamical instabilities in a planetary system (LHB-type trophysical questions, and is intimately linked to the study scenario) is unlikely, with less than 1% chance of being of . observed (Bonsor, Raymond & Augereau 2013). In the solar system, the evaporation of Jupiter family comets is References: thought to be the most effective dust production mecha- Absil, Di Folco, M´erand, Augereau et al. 2006, A&A 451, 327 nism (Nesvorn´yet al 2010). The same could happen in ex- Absil, Di Folco, M´erand, Augereau et al. 2008, A&A 487, 1041 trasolar planetary systems, for instance, a chain of planets Absil et al. 2009, ApJ 704, 150 Absil et al. 2013, A&A 555, 104 can scatter comet-like bodies inwards from a distant belt Akeson et al. 2009, ApJ 691, 1896 analogous to the Kuiper belt, and produce a high level of Augereau et al. 1999, A&A 348, 557 cometary activity (Bonsor, Augereau & Th´ebault 2012). Augereau 2009, SF2A proceedings, p. 301 This activity fades with time and is often insufficient to Beichman et al. 2005, ApJ 626, 1061 Bonsor, Augereau & Th´ebault 2012, A&A 548, 104 explain the brightest exozodis. It is possible to sustain Bonsor, Raymond & Augereau 2013, MNRAS 433, 2938 the phenomenon longer if the gravitational feedback of the Chen et al. 2006, ApJS 166, 351 belt on the planets is taken into account, resulting in the Czechowski & Mann 2010, ApJ 714, 89 (planetesimal driven) migration of the outermost planet(s) Defr`ere et al. 2011, A&A 534, 5 Defr`ere et al. 2012, A&A 546, 9 (Bonsor, Raymond, Augereau & Ormel, 2014, submitted; Di Folco, Absil, Augereau et al. 2007, A&A 475, 243 Raymond & Bonsor 2014, submitted, Fig. 4). More exotic Eiroa et al. 2013, A&A 555, 11 mechanisms may be considered, such as the slow evapora- Kimura & Mann 1998, EP&S 50, 493 Kral, Th´ebault & Charnoz 2013, A&A 558, 121 tion of planets the size of Mercury (e.g. Rappaport et al. Lebreton, Augereau, Thi et al. 2012, A&A 539, 17 2012), or the trapping of charged submicron-sized grains Lebreton, van Lieshout, Augereau et al. 2013, A&A 555, 146 by the stellar magnetic field which would help to miti- Lisse et al. 2007, ApJ 658, 584 gate the dust production rate (e.g. Ragot & Kahler, 2003; Menesson et al. 2013, ApJ 763, 119 Mukai & Yamamoto, 1979, PASJ 31, 585 Czechowski & Mann, 2010). Millan-Gabet et al. 2011, ApJ 734, 67 Concluding remarks : Near-IR interferometric observa- Nesvorn´yet al. 2010, ApJ 713, 816 Olofsson et al. 2012, A&A 542, 90 tions show that exozodis are common. Their origin is un- Ragot & Kahler 2003, ApJ 594, 1049 known but reflects the current dynamics of the innermost Rappaport et al. 2012, ApJ 752, 1 regions of extrasolar planetary systems (less than a few Smith et al. 2009, A&A 493, 299 AU) around nearby stars. They may also reveal the pres- Smith et al. 2012, MNRAS 422, 2560 Stark et al. 2009a, ApJ 703, 1188 ence of extrasolar cometary activity connecting the inner Stock et al. 2010, ApJ 724, 1238 and outer regions of planetary systems, and the presence

12 Abstracts of recently accepted papers

Origin of the wide-angle hot H2 in DG Tau: New insight from SINFONI spectro-imaging V. Agra-Amboage1, S. Cabrit2,4, C. Dougados3,4, L. E. Kristensen5, L. Ibgui2 and J. Reunanen6 1 Universidade do Porto, Faculdade de Engenharia, Departamento Engenharia fisica, SIM Unidade FCT 4006, Rua Dr. Roberto Frias, s/n 4200-465, Porto, Portugal 2 LERMA, UMR 8112 du CNRS & Observatoire de Paris, ENS, UPMC, UCP, 61 Avenue de l’Observatoire, F-75014 Paris 3 Laboratoire Franco-Chilien d’Astronomie, UMI 3386 du CNRS, 1515 Camino el observatorio, Casilla 36-D correo central, Santiago, Chili 4 IPAG, UMR 5274 du CNRS & Univ. Joseph Fourier, 414 rue de la Piscine, F-38041 Grenoble 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 6 Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Vaisalantie 20, 21500 Piikkio, Finland E-mail contact: sylvie.cabrit at obspm.fr Context: The origin of protostellar jets remains a major open question in star formation. Magneto-hydrodynamical (MHD) disk winds are an important mechanism to consider, because they would have a significant impact on planet formation and migration. Aims: We wish to test the origins proposed for the extended hot H2 at 2000 K around the atomic jet from the T Tauri star DG Tau, in order to constrain the wide-angle wind structure and the possible presence of an MHD disk wind in this prototypical source. Methods: We present spectro-imaging observations of the DG Tau jet in H2 1-0 S(1) with 0.12” angular resolution, obtained with SINFONI/VLT. Thanks to spatial deconvolution by the PSF and to careful correction for wavelength calibration and for uneven slit illumination (to within a few km s−1), we performed a thorough analysis and modeled the morphology and kinematics. We also compared our results with studies in [Fe II], [O I], and FUV-pumped H2. Absolute flux calibration yields the H2 column/volume density and emission surface, and narrows down possible shock conditions. Results:The limb-brightened H2 1-0 S(1) emission in the blue lobe is strikingly similar to FUV-pumped H2 imaged 6 yr later, confirming that they trace the same hot gas and setting an upper limit < 12km s−1 on any expansion proper motion. The wide-angle rims are at lower blueshifts (between -5 and 0km s−1) than probed by narrow long-slit spectra. We confirm that they extend to larger angle and to lower speed the onion-like velocity structure observed in optical atomic lines. The latter is shown to be steady over ≥ 4 yr but undetected in [Fe II] by SINFONI, probably due to strong iron depletion. The H2 rim thickness ≤ 14 AU rules out excitation by C-type shocks, and J-type shock speeds are constrained to ≃ 10 km s−1. Conclusions:We find that explaining the H2 1-0 S(1) wide-angle emission with a shocked layer requires either a recent outburst (15 yr) into a pre-existing ambient outflow or an excessive wind mass flux. A slow photoevaporative wind from the dense irradiated disk surface and an MHD disk wind heated by ambipolar diffusion seem to be more promising and need to be modeled in more detail. Better observational constraints on proper motion and rim thickness would also be crucial for clarifying the origin of this structure. Accepted by A & A http://arxiv.org/pdf/1402.1160

Chemo-dynamical deuterium fractionation in the early solar nebula: The origin of water on Earth and in asteroids and comets. Tobias Albertsson1, Dmitry Semenov1 and Thomas Henning1 1 Max-Planck-Institut fuer Astronomie, K¨onigstuhl 17, 69117 Heidelberg, Germany

13 E-mail contact: albertsson at mpia.de Formation and evolution of water in the Solar System and the origin of water on Earth constitute one of the most interesting questions in astronomy. The prevailing hypothesis for the origin of water on Earth is by delivery through water-rich small Solar system bodies. In this paper, the isotopic and chemical evolution of water during the early history of the solar nebula, before the onset of planetesimal formation, is studied. A gas-grain chemical model that includes multiply-deuterated species and nuclear spin-states is combined with a steady-state solar nebula model. To calculate initial abundances, we simulated 1 Myr of evolution of a cold and dark TMC1-like prestellar core. Two time- dependent chemical models of the solar nebula are calculated over 1 Myr: (1) a laminar model and (2) a model with 2D turbulent mixing. We find that the radial outward increase of the H2O D/H ratio is shallower in the chemo-dynamical nebular model compared to the laminar model. This is related to more efficient de-fractionation of HDO via rapid gas- phase processes, as the 2D mixing model allows the water ice to be transported either inward and thermally evaporated or upward and photodesorbed. The laminar model shows the Earth water D/H ratio at r ∼< 2.5 AU, while for the 2D chemo-dynamical model this zone is larger, r ∼< 9 AU. Similarly, the water D/H ratios representative of the Oort-family comets, ∼ 2.5 − 10 × 10−4, are achieved within ∼ 2 − 6 AU and ∼ 2 − 20 AU in the laminar and the 2D model, respectively. We find that with regards to the water isotopic composition and the origin of the comets, the mixing model seems to be favored over the laminar model. Accepted by ApJ http://arxiv.org/pdf/1401.6035

2MASS wide field extinction maps: V. Corona Australis Jo˜ao Alves1, Marco Lombardi2, and Charles J. Lada3 1 University of Vienna, Department of Astrophysics, T¨urkenschanzstrasse 17, 1180 Vienna, Austria 2 University of Milan, Department of Physics, via Celoria 16, I-20133 Milan, Italy 3 Harvard-Smithsonian Center for Astrophysics, Mail Stop 42, 60 Garden Street, Cambridge, MA 02138, USA E-mail contact: joao.alves at univie.ac.at We present a near-infrared extinction map of a large region (∼870 deg2) covering the isolated Corona Australis complex of molecular clouds. We reach a 1-σ error of 0.02 mag in the K-band extinction with a resolution of 3′ over the entire map. We find that the Corona Australis cloud is about three times as large as revealed by previous CO and dust emission surveys. The cloud consists of a 45 pc long complex of filamentary structure from the well known star forming Western-end (the head, N ≥ 1023 cm−2) to the diffuse Eastern-end the tail, (N ≤ 1021 cm−2). Remarkably, about two thirds of the complex both in size and mass lie beneath AV1 mag. We find that the PDF of the cloud cannot be described by a single log-normal function. Similar to prior studies, we found a significant excess at high column densities, but a log-normal + power-law tail fit does not work well at low column densities. We show that at low column densities near the peak of the observed PDF, both the amplitude and shape of the PDF are dominated by noise in the extinction measurements making it impractical to derive the intrinsic cloud PDF below AK < 0.15 mag. Above AK ∼ 0.15 mag, essentially the molecular component of the cloud, the PDF appears to be best described by a power-law with index −3, but could also described as the tail of a broad and relatively low amplitude, log-normal PDF that peaks at very low column densities. Accepted by A&A http://arxiv.org/pdf/1401.2857

On the mid-IR variability of candidate eruptive variables (EXors): a comparison be- tween Spitzer and WISE data S. Antoniucci1, T. Giannini1, G. Li Causi1 and D. Lorenzetti1 1 INAF-Osservatorio Astronomico di Roma, Via Frascati 33, Monte Porzio Catone (RM), Italy E-mail contact: simone.antoniucci at oa-roma.inaf.it Aiming to statistically study the variability in the mid-IR of young stellar objects (YSOs), we have compared the 3.6, 4.5, and 24 µm Spitzer fluxes of 1478 sources belonging to the C2D (Cores to Disks) legacy program with the

14 WISE fluxes at 3.4, 4.6, and 22 µm. From this comparison we have selected a robust sample of 34 variable sources. Their variations were classified per spectral Class (according to the widely accepted scheme of Class I/flat/II/III protostars), and per star forming region. On average, the number of variable sources decreases with increasing Class and is definitely higher in Perseus and Ophiuchus than in Chamaeleon and Lupus. According to the paradigm Class ≡ Evolution, the photometric variability can be considered to be a feature more pronounced in less evolved protostars, and, as such, related to accretion processes. Moreover, our statistical findings agree with the current knowledge of the star formation activity in different regions. The 34 selected variables were further investigated for similarities with known young eruptive variables, namely the EXors. In particular we analyzed : (1) the shape of the spectral energy distribution (SED); (2) the IR excess over the stellar ; (3) magnitude versus color variations; and (4) output parameters of model fitting. This first systematic search for EXors ends up with 11 bona fide candidates that can be considered as suitable targets for monitoring or future investigations. Accepted by ApJ http://arxiv.org/pdf/1401.1970

Stellar irradiated discs and implications on migration of embedded planets II: accreting- discs Bertram Bitsch1, Alessandro Morbidelli1, Elena Lega1, Aur´elien Crida1 1 University of Nice-Sophia Antipolis, CNRS, Observatoire de la Cˆote d’Azur, Laboratoire LAGRANGE, BP4229, 06304 NICE cedex 4, FRANCE E-mail contact: bertram.bitsch at oca.eu The strength and direction of migration of embedded low mass planets depends on the disc’s structure. It has been shown that, in discs with viscous heating and radiative transport, the migration can be directed outwards. In this paper we investigate the influence of a constant M˙ -flux through the disc, as well as the influence of the disc’s on the disc’s thermodynamics. We focus on M˙ discs, which have a net mass flux through them. Utilizing the resulting disc structure, we determine the regions of outward migration in the disc. We perform numerical hydrosimulations of M˙ discs with viscous heating, radiative cooling and stellar irradiation in 2D in the r-z-plane. We use the explicit/implicit hydrodynamical code FARGOCA that includes a full tensor viscosity and stellar irradiation, as well as a two temperature solver that includes radiation transport in the flux-limited diffusion approximation. The migration of embedded planets is studied by using torque formulae. For a disc of gas surface density and viscosity, we find that the discs thermal structure depends on the product ΣG ν and the amount of heavy elements, while the migration of planets additionally to the mentioned quantities, depends on the amount of viscosity itself. As a result of this, the disc structure can not be approximated by simple power laws. During the lifetime of the disc, the structure of the disc changes significantly in a non-linear way in the inner parts. In the late stages of the discs evolution, outward migration is only possible if the metallicity of the disc is high. For low metallicity, planets would migrate inwards and could potentially be lost. The presented disc structures and migration maps have important consequences on the formation of planets, as they can give hints on the different formation mechanisms for different types of planets as a function of metallicity. Accepted by A&A http://arxiv.org/pdf/1401.1334

Spectroscopic Confirmation of Young Planetary-Mass Companions on Wide Orbits Brendan P. Bowler1,2,3, Michael C. Liu2, Adam L. Kraus4, and Andrew W. Mann2,4,5 1 California Institute of Technology, Division of Geological and Planetary Sciences, 1200 E. California Blvd., Pasadena, CA 91101 USA 2 Institute for Astronomy, University of Hawai’i; 2680 Woodlawn Drive, Honolulu, HI 96822, USA 3 Caltech Joint Center for Planetary Astronomy Fellow 4 University of Texas at Austin, Astronomy Department, Austin, TX 78712, USA 5 Harlan J. Smith Fellow E-mail contact: bpbowler at caltech.edu

15 We present moderate-resolution (R∼4000–5000) near-infrared field spectroscopy of the young (1–5 Myr) 6–14 MJup companions ROXs 42B b and FW Tau b obtained with Keck/OSIRIS and Gemini-North/NIFS. The spectrum of ROXs 42B b exhibits clear signs of low surface common to young L dwarfs, confirming its extreme youth, cool temperature, and low mass. Overall, it closely resembles the free-floating 4–7 MJup L-type Taurus member 2MASS J04373705+2331080. The companion to FW Tau AB is more enigmatic. Our optical and near-infrared spectra show strong evidence of outflow activity and disk accretion in the form of line emission from [S II], [O I], H, Ca II, [Fe II], ′′ Paβ, and H2. The molecular hydrogen emission is spatially resolved as a single lobe that stretches ≈0. 1 (15 AU). Although the extended emission is not kinematically resolved in our data, its morphology resembles shock-excited H2 jets primarily seen in young Class 0 and Class I sources. The near-infrared continuum of FW Tau b is mostly flat and lacks the deep absorption features expected for a cool, late-type object. This may be a result of accretion-induced veiling, especially in light of its strong and sustained H emission (EW (Hα)∼>290 A).˚ Alternatively, FW Tau b may be a slightly warmer (M5–M8) accreting low-mass star or (0.03–0.15 M⊙) with an edge-on disk. Regardless, its young evolutionary stage is in stark contrast to its Class III host FW Tau AB, indicating a more rapid disk clearing timescale for the host binary system than for its wide companion. Finally, we present near-infrared spectra of the young (∼2–10 Myr) low-mass (12–15 MJup) companions GSC 6214−210 B and SR 12 C and find they best resemble low gravity M9.5 and M9 substellar templates. Accepted by ApJ http://arxiv.org/pdf/1401.7668

Herschel HIFI observations of ionised carbon in the β Pictoris debris disk G. Cataldi1,2, A. Brandeker1,2, G. Olofsson1,2, B. Larsson1, R. Liseau3, J. Blommaert4, M. Fridlund5,6, R. Ivison7,8, E. Pantin9, B. Sibthorpe10, B. Vandenbussche4 and Y. Wu11 1 AlbaNova University Centre, Stockholm University, Department of Astronomy, SE-106 91 Stockholm, Sweden 2 Stockholm University Astrobiology Centre, SE-106 91 Stockholm, Sweden 3 Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, Onsala, Sweden 4 Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium 5 Institute of Planetary Research, German Aerospace Center, Rutherfordstrasse 2, 124 89 Berlin, Germany 6 Leiden Observatory, University of Leiden, P.O. Box 9513, NL-2300 RA Leiden, The Netherlands 7 UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, United Kingdom 8 Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, United Kingdom 9 Laboratoire AIM, CEA/DSM - CNRS - Universit´eParis Diderot, IRFU/Service d’Astrophysique, Bˆat. 709, CEA- Saclay, 91191 Gif-sur-Yvette Cedex, France 10 SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands 11 Department of Astronomy and Astrophysics, University of Toronto, ON M5S 3H4, Canada E-mail contact: gianni.cataldi at astro.su.se Context: The dusty debris disk around the ∼20Myr old main-sequence A-star β Pictoris is known to contain gas. Evidence points towards a secondary origin of the gas as opposed to being a direct remnant from the initial proto- planetary disk, although the dominant gas production mechanism is so far not identified. The origin of the observed overabundance of C and O compared to solar abundances of metallic elements, e.g. Na and Fe, is also unclear. Aims: Our goal is to constrain the spatial distribution of C in the disk, and thereby the gas origin and its abundance pattern. Methods: We used the HIFI instrument aboard the Herschel Space Observatory to observe and spectrally resolve CII emission at 158 µm from the β Pic debris disk. Assuming a disk in Keplerian rotation and a model for the line emission from the disk, we use the spectrally resolved line profile to constrain the spatial distribution of the gas. Results: We detect the CII 158 µm emission. Modelling the shape of the emission line shows that most of the gas is +1.3 −2 located around ∼100AU or beyond. We estimate a total C gas mass of 1.3−0.5 × 10 M⊕ (central 90% confidence interval). The data suggest that more gas is located on the southwest side of the disk than on the northeast side. The shape of the emission line is consistent with the hypothesis of a well-mixed gas (constant C/Fe ratio throughout the disk). Assuming instead a spatial profile expected from a simplified accretion disk model, we found it to give a significantly worse fit to the observations.

16 Conclusions: Since the bulk of the gas is found outside 30 AU, we argue that the cometary objects known as “falling evaporating bodies” are unlikely to be the dominant source of gas; production from grain-grain collisions or photodes- orption seems more likely. The incompatibility of the observations with a simplified accretion disk model could favour a preferential depletion explanation for the overabundance of C and O, although it is unclear how much this conclusion is affected by the simplifications made. More stringent constraints on the spatial distribution will be available from ALMA observations of CI emission at 609 µm. Accepted by Astronomy and Astrophysics http://arxiv.org/pdf/1312.0924

Discovery of Hα Emission from the Close Companion Inside the Gap of Transitional Disk HD142527 L.M. Close1, K.B. Follette1, J.R. Males1,6, A. Puglisi2, M. Xompero2, D. Apai1,3, J. Najita4, A.J. Weinberger5, K. Morzinski1,6 , T.J. Rodigas1, P. Hinz1, V. Bailey1, R. Briguglio2 1 Steward Observatory, University of Arizona, Tucson, AZ 85721, USA 2 INAF - Osservatorio Astrofisico di Arcetri, I-50125, Firenze, Italy 3 Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA 4 NOAO, 950 N Cherry Ave. Tucson, AZ 85719, United States 5 Carnegie Institution DTM, 5241 Broad Branch Rd, Washington, DC 20015 USA 6 NASA Sagan Fellow E-mail contact: lclose at as.arizona.edu We utilized the new high-order 585 actuator Magellan Adaptive Optics system (MagAO) to obtain very high-resolution visible light images of HD142527 with MagAO’s VisAO science camera. In the median seeing conditions of the 6.5m Magellan telescope (0.5–0.7′′), we find MagAO delivers 24-19% Strehl at Hα (0.656 µm). We detect a faint companion (HD142527B) embedded in this young transitional disk system at just 86.3±1.9 mas (∼12 AU) from the star. The companion is detected in both Hα and a continuum filter (∆mag=6.334±0.20 mag at Hα and 7.50±0.25 mag in the continuum filter). This provides confirmation of the tentative companion discovered by Biller and co-workers with sparse aperture masking at the 8m VLT. The Hα emission from the ∼0.25 companion (EW=180 Angstroms) implies a mass accretion rate of ∼5.9×10−10 Msun yr−1, and a total accretion luminosity of 1.2% Lsun. Assuming a similar accretion rate, we estimate that a 1 Jupiter mass gas giant could have considerably better (50- 1,000x) planet/star contrasts at Hα than at H band (COND models) for a range of optical extinctions (3.4–0 mag). We suggest that ∼0.5–5 Mjup extrasolar planets in their gas accretion phase could be much more luminous at H-alpha than in the NIR. This is the motivation for our new MagAO GAPplanetS survey for extrasolar planets. Accepted by ApJL http://arxiv.org/pdf/1401.1273

First results from the CALYPSO IRAM-PdBI survey - III. Monopolar jets driven by a proto-binary system in NGC1333-IRAS2A C. Codella1, A.J. Maury2,3, F. Gueth4, S. Maret5, A. Belloche6, S. Cabrit7,5 and P. Andr´e8 1 INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden street, Cambridge, MA 02138, USA 3 ESO, Karl Schwarzchild Str. 2, 85748 Garching bei M¨unchen, Germany 4 IRAM, 300 rue de la Piscine, 38406 Saint Martin d’H`eres, France 5 UJF-Grenoble1/CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, 38041, France 6 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, 53121 Bonn, Germany 7 LERMA, Observatoire de Paris, CNRS, ENS, UPMC, UCP, 61 Av. de l’Observatoire, 75014 Paris, France 8 Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu - CNRS -Universit´e Paris Diderot, CE Saclay, 91191 Gif-sur-Yvette Cedex, France E-mail contact: codella at arcetri.astro.it

17 Context: The earliest evolutionary stages of low-mass protostars are characterised by hot and fast jets which remove angular momentum from the circumstellar disk, thus allowing mass accretion onto the central object. However, the launch mechanism is still being debated. Aims: We would like to exploit high-angular (∼ 0.8 arcsec) resolution and high-sensitivity images to investigate the origin of protostellar jets using typical molecular tracers of shocked regions, such as SiO and SO. Methods: We mapped the inner 22 arcsec of the NGC1333–IRAS2A protostar in SiO(5–4), SO(65– 54), and the continuum emission at 1.4 mm using the IRAM Plateau de Bure interferometer in the framework of the CALYPSO IRAM large program. Results: For the first time, we disentangle the NGC1333–IRAS2A Class 0 object into a proto-binary system revealing two protostars (MM1, MM2) separated by ∼ 560 AU, each of them driving their own jet, while past work considered a single protostar with a quadrupolar outflow. We reveal (i) a clumpy, fast (up to −1 |V –VLSR|≥ 50 km s ), and blueshifted jet emerging from the brightest MM1 source, and (ii) a slower redshifted jet, 5 −3 driven by MM2. Silicon monoxide emission is a powerful tracer of high-excitation (Tkin ≥ 100 K; nH2 ≥ 10 cm ) jets close to the launching region. At the highest velocities, SO appears to mimic SiO tracing the jets, whereas at velocities close to the systemic one, SO is dominated by extended emission, tracing the cavity opened by the jet. Conclusions: Both jets are intrinsically monopolar, and intermittent in time. The dynamical time of the SiO clumps is ≤ 30–90 yr, indicating that one-sided ejections from protostars can take place on these timescales. Accepted by Astronomy & Astrophysics Letters http://arxiv.org/pdf/1401.6672

CSI 2264: Simultaneous optical and infrared light curves of young disk-bearing stars in NGC 2264 with CoRoT and Spitzer– evidence for multiple origins of variability Ann Marie Cody1, John Stauffer1, Annie Baglin2, Giuseppina Micela3, Luisa M. Rebull1, Ettore Flaccomio3, Mar´ıa Morales-Calder´on4, Suzanne Aigrain5, J`erˆome Bouvier6, Lynne A. Hillenbrand7, Robert Gutermuth8, Inseok Song9, Neal Turner10, Silvia H. P. Alencar11, Konstanze Zwintz12, Peter Plavchan13, John Carpenter7, Krzysztof Findeisen7, Sean Carey1, Susan Terebey14, Lee Hartmann15, Nuria Calvet15, Paula Teixeira16, Frederick J. Vrba17, Scott Wolk18, Kevin Covey19, Katja Poppenhager18, Hans Moritz G¨unther18, Jan Forbrich16,18, Barbara Whitney20, Laura Affer3, William Herbst21, Joseph Hora18, David Barrado4, Jon Holtzman22, Franck Marchis23, Kenneth Wood24, Marcelo Medeiros Guimar˜aes25, Jorge Lillo Box4, Ed Gillen5, Amy McQuillan26, Catherine Espaillat27, Lori Allen28, Paola D’Alessio29, Fabio Favata30 1Spitzer Science Center, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125, USA 2LESIA, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195, Meudon, France 3INAF - Osservatorio Astro- nomico di Palermo, Piazza del Parlamento 1, 90134, Palermo, Italy 4Centro de Astrobiologia, Dpto. de Astrofisica, INTA-CSIC, PO BOX 78, E-28691, ESAC Campus, Villanueva de la Ca˜nada, Madrid, Spain 5Department of Astro- physics, Denys Wilkinson Building, University of Oxford, Oxford OX1 3RH, UK 6UJF-Grenoble 1 / CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041, France 7Astronomy Department, California Institute of Technology, Pasadena, CA 91125, USA 8Dept. of Astronomy, University of Mas- sachusetts, Amherst, MA 01003 9Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602- 2451, USA 10Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA 11Departamento de F´ısica – ICEx – UFMG, Av. Antˆonio Carlos 6627, 30270-901, Belo Horizonte, MG, Brazil 12Instituut voor Ster- renkunde, K. U. Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium 13Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA 14Department of Physics and Astronomy, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032 15Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105, USA 16University of Vienna, Department of Astro- physics, T¨urkenschanzstr. 17, 1180 Vienna, Austria 17U.S. Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001, USA 18Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA 19Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA 20Astronomy Department, University of Wisconsin- Madison, 475 N. Charter St., Madison, WI 53706, USA 21Astronomy Department, Wesleyan University, Middletown, CT 06459, USA 22Department of Astronomy, New Mexico State University, Box 30001, Las Cruces, NM 88003, USA 23Carl Sagan Center at the SETI Institute, 189 Bernardo Av., Mountain View, CA 94043, USA 24School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9AD, UK 25Departamento de Fisica e Matem´atica - UFSJ - Rodovia MG 443 KM7 -36420-000 - Ouro Branco - MG - Brazil 26School of Physics and Astronomy, Raymond and Beverly Sackler, Faculty of Exact Sciences, Tel Aviv University, 69978 Tel Aviv, Israel

18 27Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA 28National Optical Astronomy Observatories, Tucson, AZ, USA 29Centro de Radioastronomia y Astrofisica, UNAM, Apartado Postal 3-72 (Xangari), 58089 Morelia, Michoacan, Mexico 30European Space Agency, 8-10 rue Mario Nikis, F-75738 Paris Cedex 15, France E-mail contact: amc at ipac.caltech.edu We present the Coordinated Synoptic Investigation of NGC 2264, a continuous 30- multi-wavelength photometric monitoring campaign on more than 1000 young cluster members using 16 telescopes. The unprecedented combination of multi-wavelength, high-precision, high-cadence, and long-duration data opens a new window into the time domain behavior of young stellar objects. Here we provide an overview of the observations, focusing on results from Spitzer and CoRoT. The highlight of this work is detailed analysis of 162 classical T Tauri stars for which we can probe optical and mid-infrared flux variations to 1% amplitudes and sub-hour timescales. We present a morphological variability census and then use metrics of periodicity, stochasticity, and symmetry to statistically separate the light curves into seven distinct classes, which we suggest represent different physical processes and geometric effects. We provide distributions of the characteristic timescales and amplitudes, and assess the fractional representation within each class. The largest category (>20%) are optical “dippers” having discrete fading events lasting ∼1–5 days. The degree of correlation between the optical and infrared light curves is positive but weak; notably, the independently assigned optical and infrared morphology classes tend to be different for the same object. Assessment of flux variation behavior with respect to (circum)stellar properties reveals correlations of variability parameters with Hα emission and with effective temperature. Overall, our results point to multiple origins of young star variability, including circumstellar obscuration events, hot spots on the star and/or disk, accretion bursts, and rapid structural changes in the inner disk. Accepted by Astron. J. http://web.ipac.caltech.edu/staff/amc/codyetal2014.pdf http://arxiv.org/pdf/1401.6582

Near-IR Spectroscopic Monitoring of Class I Protostars: Variability of Accretion and Wind Indicators Michael Connelley1 and Tom Greene2 1 University of Hawaii Institute for Astronomy, 640 N. Aohoku Pl., Hilo, HI 96720, USA 2 NASA Ames Research Center, M.S. 245-6, Moffett Field, CA 94035, USA E-mail contact: msc at ifa.hawaii.edu We present the results of a program that monitored the near-IR spectroscopic variability of a sample of 19 embedded protostars. Spectra were taken on time intervals from 2 days to 3 years, over a wavelength range from 0.85 µm to 2.45 µm, for 4-9 epochs of observations per target. We found that the spectra of all targets are variable, and that every emission feature observed is also variable (although not for all targets). With one exception, there were no drastic changes in the continua of the spectra, nor did any line completely disappear, nor did any line appear that was not previously apparent. This analysis focuses on understanding the connection between accretion (traced by H Br γ and CO) and the wind (traced by He I, [FeII], and sometimes H2). For both accretion and wind tracers, the median variability was constant versus time interval between observations, however the maximum variability that we observed increased with time interval between observations. Extinction is observed to vary within the minimum sampling time of 2 days, suggesting extinguishing material within a few stellar radii at high disk latitudes. The variability of [FeII] and H2 were correlated for most (but not all) of the 7 YSOs showing both features, and the amplitude of the variability depends on the veiling. Although the occurrence of CO and Br γ emission are connected, their variability is uncorrelated, suggesting that these emissions originate in separate regions near the protostar (e.g., disk and wind). The variability of Br γ and wind tracers were found to be positively correlated, negatively correlated, or uncorrelated, depending on the target. The variability of Br γ, [FeII], and H2 always lies on a plane, although the orientation of the plane in 3D depends on the target. While we do not understand all interactions behind the variability that we observed, we have shown that spectroscopic variability is a powerful tool towards understanding the star formation process. Accepted by The Astronomical Journal

19 Extreme Infrared Variables from UKIDSS - I. A Concentration in Star Forming Regions C. Contreras Pe˜na1, P.W. Lucas1, D. Froebrich2, M.S.N. Kumar3, J. Goldstein1J.E. Drew1, A. Adamson4, C.J. Davis5, G. Barentsen1 and N.J. Wright1 1 Centre for Astrophysics Research, University of Hertfordshire, Hatfield, AL10 9AB, UK 2 Centre for Astrophysics and Planetary Science, University of Kent, Canterbury CT2 7NH, UK 3 Centro de Astrofsica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal 4 Joint Astronomy Centre, 660 North Aohoku Place, Hilo, HI 96720, USA 5 Astrophysics Research Institute, Liverpool John Moores University, Egerton Wharf, Birkenhead CH41 1LD, UK E-mail contact: c.contreras at herts.ac.uk We present initial results of the first panoramic search for high-amplitude near-infrared variability in the Galactic Plane. We analyse the widely separated two- K-band photometry in the 5th and 7th data releases of the UKIDSS Galactic Plane Survey. We find 45 stars with ∆K > 1 mag, including 2 previously known OH/IR stars and a . Even though the mid-plane is not yet included in the dataset, we find the majority (66%) of our sample to be within known star forming regions (SFRs), with two large concentrations in the OB2 association (11 stars) and the Cygnus-X complex (12 stars). Sources in SFRs show spectral energy distributions (SEDs) that support classification as Young Stellar Objects (YSOs). This indicates that YSOs dominate the Galactic population of high amplitude infrared variable stars at low and therefore likely dominate the total high amplitude population. Spectroscopic follow up of the DR5 sample shows at least four stars with clear characteristics of eruptive pre-main-sequence variables, two of which are deeply embedded. Our results support the recent concept of eruptive variability comprising a continuum of outburst events with different timescales and luminosities, but triggered by a similar physical mechanism involving unsteady accretion. Also, we find what appears to be one of the most variable classical Be stars. Accepted by MNRAS http://arxiv.org/pdf/1401.2336

Strong Biases in Estimating the Time Dependence of Mass Accretion Rates in Young Stars Nicola Da Rio1, Rob D. Jeffries2, Carlo F. Manara3 and Massimo Robberto4 1 University of Florida, USA 2 Keele University, UK 3 ESO, Germany 4 STScI, USA E-mail contact: ndario at ufl.edu The temporal decay of mass accretion in young stars is a fundamental tracer of the early evolution of circumstellar disks. Through population syntheses, we study how correlated uncertainties between the estimated parameters of young stars (luminosity, temperature, mass, age) and mass accretion rates M˙ acc, as well as observational selection −η effects, can bias the temporal decay of mass accretion rates (M˙ acc ∝ t ) inferred from a comparison of measured M˙ acc with isochronal ages in young stellar clusters. We find that the presence of realistic uncertainties reduces the measured value of η by up to a factor of 3, leading to the inference of shallower decays than the true value. This suggests a much faster temporal decay of M˙ acc than generally assumed. When considering the minimum uncertainties in ages affecting the Orion Nebula Cluster, the observed value > η ∼ 1.4, typical of Galactic star forming regions, can only be reproduced if the real decay exponent is η ∼ 4. This effect becomes more severe if one assumes that observational uncertainties are larger, as required by some fast star formation scenarios. Our analysis shows that while selection effects due to sample incompleteness do bias η, they can not alter this main result and strengthen it in many cases. A remaining uncertainty in our work is that it applies to the most commonly used and simple relationship between M˙ acc, the accretion luminosity and the stellar parameters. We briefly explore how a more complex interplay between these quantities might change the results. Accepted by MNRAS http://arxiv.org/pdf/1401.5062v1

20 GeMS in the Outer : Near-Infrared Imaging of Three Young Clusters at Large Galactic Radii T.J. Davidge1 1 Dominion Astrophysical Observatory, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC Canada V9E 2E7 E-mail contact: tim.davidge at nrc.ca Images recorded with the Gemini South Adaptive Optics Imager (GSAOI) and corrected for atmospheric seeing by the Gemini Multiconjugate Adaptive Optics System (GeMS) are used to investigate the stellar contents of the young outer Galactic disk clusters Haffner 17, NGC 2401, and NGC 3105. Ages estimated from the faint end of the main sequence (MS) and the ridgeline of the pre-main sequence (PMS) on the (K, J − K) color-magnitude diagrams are consistent with published values that are based on the MS turn-off, with the GSAOI data favoring the younger end of the age range for NGC 2401 in the literature. The mass function (MF) of NGC 2401 is similar to that in the Solar neighborhood, and stars spanning a wide range of masses in this cluster have similar clustering properties on the sky. It is concluded that NGC 2401 is not evolved dynamically. In contrast, the MF of Haffner 17 differs significantly from that in the Solar neighborhood over all masses covered by these data, while the MF of NGC 3105 is deficient in objects with sub-solar masses when compared with the Solar neighborhood. Low mass objects in Haffner 17 and NGC 3105 are also more uniformly distributed on the sky than brighter, more massive, MS stars. This is consistent with both clusters having experienced significant dynamical evolution. Accepted by ApJ http://arxiv.org/pdf/1401.0710

Atomic jet from SMM1 (FIRS1) in Serpens uncovers protobinary companion Odysseas Dionatos1,2,3, Jes K. Jørgensen3,2 and Paula S. Teixeira1, Manuel G¨udel1, and E. Bergin4 1 Department of Astrophysics, University of Vienna, T¨urkenschanzstrasse 17, A-1180, Vienna, Austria 2 Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5 – 7, DK-1350 Copenhagen K. Denmark 3 Niels Bohr Institute, University of Copenhagen. Juliane Maries Vej 30, DK-2100 Copenhagen Ø. Denmark 4 Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, Michigan 48109, USA E-mail contact: odysseas.dionatos at univie.ac.at We report on the detection of an atomic jet associated with the protostellar source SMM1 (FIRS1) in Serpens. The jet is revealed in [FeII] and [NeII] line maps observed with Spitzer/IRS, and further confirmed in HiRes IRAC and MIPS images. It is traced very close to SMM1 and peaks at 5′′ from the source at a position angle of ∼125◦. In contrast, molecular hydrogen emission becomes prominent at distances >5′′ from the protostar and extends at a position angle of 160◦. The morphological differences suggest that the atomic emission arises from a companion source, lying in the foreground of the envelope surrounding the embedded protostar SMM1. In addition the molecular and atomic lines mapped with Spitzer disentangle the large scale CO (3-2) emission observed in the region into two distinct bipolar outflows, giving further support to a protobinary source setup. Analysis at the peaks of the [FeII] jet 5 6 −3 show that emission arises from warm and dense gas (T 1000 K, ne 10 - 10 cm ). The mass flux of the jet derived 7 −1 independently for the [FeII] and [NeII] lines is 10 M⊙ yr , pointing to a more evolved Class I/II protostar as the driving source. All existing evidence indicate that SMM1 is a protobinary source. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1401.3249

OGLE-LMC-ECL-11893: The discovery of a long-period eclipsing binary with a circum- stellar disk Subo Dong1, Boaz Katz2,3, Jose L. Prieto4,5, Andrzej Udalski6,7, Szymon Kozlowski6,7, R.A. Street8, RoboNet Collaboration 1 Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Road 5, Hai Dian District, Beijing

21 100871, China 2 Institute for Advanced Study, 1 Einstein Dr. 3 John N. Bahcall Fellow 4 Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Peyton Hall, Princeton, NJ 08544 5 Carnegie-Princeton Fellow 6 Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland 7 OGLE Collaboration 8 Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, suite 102, Goleta, CA 93117, USA E-mail contact: dongsubo at gmail.com We report the serendipitous discovery of a disk-eclipse system OGLE-LMC-ECL-11893. The eclipse occurs with a period of 468 days, a duration of about 15 days and a deep (up to ∆mI ∼ 1.5), peculiar and asymmetric profile. A possible origin of such an eclipse profile involves a circumstellar disk. The presence of the disk is confirmed by the H-α line profile from the follow-up spectroscopic observations, and the star is identified as Be/Ae type. Unlike the previously known disk-eclipse candidates (Epsilon Aurigae, EE Cephei, OGLE-LMC-ECL-17782, KH 15D), the eclipses of OGLE-LMC-ECL-11893 retain the same shape throughout the span of ∼17 years (13 orbital periods), indicating no measurable orbital precession of the disk. Accepted by http://arxiv.org/pdf/1401.1195

The TW Hydrae Association : trigonometric parallaxes and kinematic analysis C. Ducourant1,2,3, R. Teixeira3,1, P.A.B. Galli3,1, J.F. Le Campion1, A. Krone-Martins6,3,1, B. Zuckerman4, G. Chauvin5, and I. Song7 1 Univ. Bordeaux, LAB, UMR 5804, F-33270, Floirac, France 2 CNRS, LAB, UMR 5804, F-33270, Floirac, France, Observatoire Aquitain des Sciences de l’Univers, CNRS-UMR 5804, BP 89, 33270 Floirac, France 3 Instituto de Astronomia, Geof´ısica e Ciˆencias Atmosf´ericas, Universidade de S˜ao Paulo, Rua do Mat˜ao, 1226 - Cidade Universit´aria, 05508-900 S˜ao Paulo - SP, Brazil 4 Department of Physics & Astronomy, UCLA, Los Angeles, CA 90095 USA 5 Laboratoire d’Astrophysique, Observatoire de Grenoble, 414, Rue de la piscine, 38400 Saint-Martin d’H´eres, France 6 SIM, Faculdade de Ciˆencias, Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016, Lisboa, Portugal 7 Department of Physics & Astronomy, the University of Georgia, Athens, GA 30605 USA E-mail contact: christine.ducourant at free.fr The nearby TW Hydrae Association (TWA) is currently a benchmark for the study of formation and evolution of young low-mass stars, circumstellar disks and the imaging detection of planetary companions. For such studies, it is crucial to evaluate the distance to group members in order to access their physical properties. Membership of several stars is strongly debated and age estimates vary from one author to another with doubts about coevality. We revisit the kinematic properties of the TWA in light of new trigonometric parallaxes and proper motions to derive the dynamical age of the association and physical parameters of kinematic members. Using observations performed with the NTT/ESO telescope we measured trigonometric parallaxes and proper motions for 13 stars in TWA. With the convergent point method we identify a co-moving group with 31 TWA stars. We deduce kinematic distances for 7 members of the moving group that lack trigonometric parallaxes. A traceback strategy is applied to the stellar space motions of a selection of 16 of the co-moving objects with accurate and reliable data yielding a dynamical age for the association of t = 7.5 ± 0.7 Myr. Using our new parallaxes and photometry available in the literature we derive stellar ages and masses from theoretical evolutionary models. With new parallax and proper motion measurements from this work and current astrometric catalogs we provide an improved and accurate database for TWA stars to be used in kinematical analysis. We conclude that the dynamical age obtained via traceback strategy is consistent with previous age estimates for the TWA, and is also compatible with the average ages derived in the present paper from evolutionary models for pre-main sequence stars. Accepted by A&A http://arxiv.org/pdf/1401.1935

22 Molecular Outflows Driven by Low-Mass Protostars. I. Correcting for Underestimates When Measuring Outflow Masses and Dynamical Properties Michael M. Dunham1,2, H´ector G. Arce2, Diego Mardones3, Jeong-Eun Lee4, Brenda C. Matthews5, Amelia M. Stutz6 and Jonathan P. Williams7 1 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138, USA 2 Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520, USA 3 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 4 Department of Astronomy and Space Science, Kyung Hee University, Yongin, Gyeonggi 446-701, Republic of Korea 5 National Research Council of Canada, Herzberg Astronomy & Astrophysics, 5071 W. Saanich Road, Victoria, BC V9E 2E7, Canada 6 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, D-69117, Heidelberg, Germany 7 Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA E-mail contact: mdunham at cfa.harvard.edu We present a survey of 28 molecular outflows driven by low-mass protostars, all of which are sufficiently isolated spatially and/or kinematically to fully separate into individual outflows. Using a combination of new and archival data from several single-dish telescopes, 17 outflows are mapped in 12CO (2–1) and 17 are mapped in 12CO (3–2), with 6 mapped in both transitions. For each outflow, we calculate and tabulate the mass (Mflow), momentum (Pflow), kinetic energy (Eflow), mechanical luminosity (Lflow), and force (Fflow) assuming optically thin emission in LTE at an excitation temperature, Tex, of 50 K. We show that all of the calculated properties are underestimated when calculated under these assumptions. Taken together, the effects of opacity, outflow emission at low velocities confused with ambient cloud emission, and emission below the sensitivities of the observations increase outflow masses and dynamical properties by an order of magnitude, on average, and factors of 50–90 in the most extreme cases. Different (and non-uniform) excitation temperatures, inclination effects, and dissociation of molecular gas will all work to further increase outflow properties. Molecular outflows are thus almost certainly more massive and energetic than commonly reported. Additionally, outflow properties are lower, on average, by almost an order of magnitude when calculated from the 12CO (3–2) maps compared to the 12CO (2–1) maps, even after accounting for different opacities, map sensitivities, and possible excitation temperature variations. It has recently been argued in the literature that the 12CO (3–2) line is subthermally excited in outflows, and our results support this finding. Accepted by ApJ http://arxiv.org/pdf/1401.2391

Relating jet structure to photometric variability: the Herbig Ae star HD 163296 L.E. Ellerbroek1, L. Podio2,3, C. Dougados4,2, S. Cabrit5,2, M.L. Sitko6,7,24, H. Sana8, L. Kaper1, A. de Koter1,9, P.D. Klaassen10, G.D. Mulders11, I. Mendigut´ıa12, C.A. Grady13,14, K. Grankin15, H. van Winckel9, F. Bacciotti3, R.W. Russell16,24, D.K. Lynch16,17,24, H.B. Hammel7,18,24, L.C. Beerman6,19,24, A.N. Day6,20,24, D.M. Huelsman6,21,24, C. Werren6,24, A. Henden22, and J. Grindlay23 1 Astronomical Institute “Anton Pannekoek”, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands 2 Institut de Plan´etologie et d’Astrophysique de Grenoble, 414, Rue de la Piscine, 38400 St-Martin d’H´eres, France 3 INAF - Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125, Florence, Italy 4 CNRS/Universidad de Chile, Laboratoire Franco-Chilien dAstronomie (LFCA), UMI 3386, Santiago, Chile 5 LERMA, Observatoire de Paris, UMR 8112 du CNRS, 61 Av. de lObservatoire, 75014, Paris, France 6 Department of Physics, University of Cincinnati, Cincinnati OH 45221, USA 7 Space Science Institute, 4750 Walnut Street, Boulder, CO 80303, USA 8 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 9 Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200B, 3001 Leuven, Belgium 10 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 11 Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721, USA 12 Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978, USA 13 Eureka Scientific, Inc., Oakland, CA 94602, USA 14 Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771,

23 USA 15 Crimean Astrophysical Observatory, Scientific Research institute, 98409, Crimea, Nauchny, Ukraine 16 The Aerospace Corporation, Los Angeles, CA 90009, USA 17 Thule Scientific, Topanga, CA 90290, USA 18 Associated Universities for Research in Astronomy, Inc., 1212 New York Ave. NW, Washington, DC 20005, USA 19 Department of Astronomy, University of Washington, Seattle, WA 98105, USA 20 Department of Physics, Miami University, Oxford, OH 45056, USA 21 Department of Management Science and Engineering, Stanford University, Stanford, CA 94305, USA 22 American Association of Variable Star Observers, 49 Bay State Road, Cambridge, MA 02138, USA 23 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 24 Visiting Astronomer, Infrared Telescope Facility, operated by the University of Hawaii under Cooperative Agreement 08AE38A with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program. E-mail contact: l.e.ellerbroek at uva.nl Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This “jet fossil record” can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) VLT/X-shooter spectra of the jet from the Herbig Ae star HD 163296. We determine physical conditions in the knots, as well as their kinematic “launch epochs”. Knots are formed simultaneously on either side of the disk, with a regular interval of ∼16 yr. The velocity dispersion versus jet velocity and the energy input are comparable in both lobes. However, the mass loss rate, velocity, and shock conditions are asymmetric. We find M˙ jet/M˙ acc ∼ 0.01–0.1, consistent with magneto-centrifugal jet launching models. No evidence for dust is found in the high-velocity jet, suggesting it is launched within the sublimation radius (<0.5 AU). The jet inclination measured from proper motions and radial velocities confirms it is perpendicular to the disk. A tentative relation is found between the structure of the jet and the photometric variability of the source. Episodes of NIR brightening were previously detected and attributed to a dusty disk wind. We report for the first time significant optical fadings lasting from a few days up to a year, coinciding with the NIR brightenings. These are likely caused by dust lifted high above the disk plane; this supports the disk wind scenario. The disk wind is launched at a larger radius than the high-velocity atomic jet, although their outflow variability may have a common origin. No significant relation between outflow and accretion variability could be established. Our findings confirm that this source undergoes periodic ejection events, which may be coupled with dust ejections above the disk plane. Accepted by A&A http://arxiv.org/pdf/1401.3744

A Density Dependence for Protostellar Luminosity in Class I Sources: Collaborative Accretion Bruce G. Elmegreen1, Rachel Hurst2, and Xavier Koenig3 1 IBM Research Division, T.J. Watson Research Center, Yorktown Hts., NY 10598 2 Scarsdale High School, 1057 White Plains Rd, Scarsdale, NY 10583 3 Department of Astronomy, Yale University, New Haven, CT 06520, USA E-mail contact: bge at us.ibm.com Class I protostars in three high-mass star-forming regions are found to have correlations among the local projected density of other Class I protostars, the summed flux from these other protostars, and the protostellar luminosity in the WISE 22 µm band. Brighter Class I sources form in higher-density and higher-flux regions, while low luminosity sources form anywhere. These correlations depend slightly on the number of neighbors considered (from 2 to 20) and could include a size-of-sample effect from the initial mass function (i.e., larger numbers include rarer and more massive stars). Luminosities seem to vary by neighborhood with nearby protostars having values proportional to each other and higher density regions having higher values. If Class I luminosity is partially related to the accretion rate, then this luminosity correlation is consistent with the competitive accretion model, although it is more collaborative than competitive. The correlation is also consistent with primordial mass segregation, and could explain why the stellar initial mass function resembles the dense core mass function even when cores form multiple stars.

24 Accepted by ApJL http://arxiv.org/pdf/1401.4016

Star Formation Relations in Nearby Molecular Clouds Neal J. Evans II1, Amanda Heiderman1 and Nalin Vutisalchavakul1 1 The University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712, USA E-mail contact: nje at astro.as.utexas.edu We test some ideas for star formation relations against data on local molecular clouds. On a cloud by cloud basis, the relation between the surface density of star formation rate and surface density of gas divided by a free-fall time, calculated from the mean cloud density, shows no significant correlation. If a crossing time is substituted for the free-fall time, there is even less correlation. Within a cloud, the star formation rate volume and surface densities increase rapidly with the corresponding gas densities, faster than predicted by models using the free-fall time defined from the local density. A model in which the star formation rate depends linearly on the mass of gas above a visual extinction of 8 mag describes the data on these clouds, with very low dispersion. The data on regions of very massive star formation, with improved star formation rates based on free-free emission from ionized gas, also agree with this linear relation. Accepted by Astrophysical Journal http://arxiv.org/pdf/1401.3287

The chemical evolution in the early phases of massive star formation. I T. Gerner1, H. Beuther1, D. Semenov1, H. Linz1, T. Vasyunina2,3, S. Bihr1, Y. L. Shirley4 and Th. Henning1 1 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, D-69117 Heidelberg, Germany 2 Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA 3 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, D-53121, Bonn, Germany 4 Steward Observatory, University of Arizona, Tucson, AZ 85721, USA E-mail contact: gerner at mpia.de Understanding the chemical evolution of young (high-mass) star-forming regions is a central topic in star formation research. Chemistry is employed as a unique tool 1) to investigate the underlying physical processes and 2) to characterize the evolution of the chemical composition. With these aims in mind, we observed a sample of 59 high- mass star-forming regions at different evolutionary stages varying from the early starless phase of infrared dark clouds to high-mass protostellar objects to hot molecular cores and, finally, ultra-compact Hii regions at 1mm and 3mm with the IRAM 30 m telescope. We determined their large-scale chemical abundances and found that the chemical composition evolves along with the evolutionary stages. On average, the molecular abundances increase with time. We modeled the chemical evolution, using a 1D physical model where density and temperature vary from stage to stage coupled with an advanced gas-grain chemical model and derived the best-fit χ2 values of all relevant parameters. A satisfying overall agreement between observed and modeled column densities for most of the molecules was obtained. With the best-fit model we also derived a chemical age for each stage, which gives the timescales for the transformation between two consecutive stages. The best-fit chemical ages are ∼ 10000 years for the IRDC stage, ∼ 60000 years for the HMPO stage, ∼ 40000 years for the HMC stage, and ∼ 10000 years for the UCHii stage. Thus, the total chemical timescale for the entire evolutionary sequence of the high-mass star formation process is on the order of 105 years, which is consistent with theoretical estimates. Furthermore, based on the approach of a multiple-line survey of unresolved data, we were able to constrain an intuitive and reasonable physical and chemical model. The results of this study can be used as chemical templates for the different evolutionary stages in high-mass star formation. Accepted by A&A http://arxiv.org/pdf/1401.6382

25 The role of planetesimal fragmentation on giant planet formation O.M. Guilera1,2, G.C. de El´ıa1,2, A. Brunini1,2 and P.J. Santamar´ıa1,2 1 Grupo de Ciencias Planetarias, Facultad de Ciencias Astron´omicas y Geof´ısicas, Univ. Nac. de La Plata, Argentina 2 Grupo de Ciencias Planetarias, Instituto de Astrof´ısica de La Plata (Consejo Nacional de Investigaciones Cientificas y T´ecnicas - Universidad Nacional de La Plata), Argentina E-mail contact: oguilera at fcaglp.unlp.edu.ar Context. In the standard scenario of planet formation, terrestrial planets and the cores of the giant planets are formed by accretion of planetesimals. As planetary embryos grow the planetesimal velocity dispersion increases due to gravitational excitations produced by embryos. The increase of planetesimal relative velocities causes the fragmentation of them due to mutual collisions. Aims.We study the role of planetesimal fragmentation on giant planet formation. We analyze how planetesimal fragmentation modifies the growth of giant planet’s cores for a wide range of planetesimal sizes and disk masses. Methods. We incorporate a model of planetesimal fragmentation into our model of in situ giant planet formation. We calculate the evolution of the solid surface density (planetesimals plus fragments) due to the accretion by the planet, migration and fragmentation. Results. The incorporation of planetesimal fragmentation significantly modifies the process of planetary formation. If most of the mass loss in planetesimal collisions is distributed in the smaller fragments, planetesimal fragmentation inhibits the growth of the embryo for initial planetesimals of radii lower than 10 km. Only for initial planetesimals of 100 km of radius, and disks greater than 0.06 M⊙, embryos achieve masses greater than the mass of the Earth. However, even for such big planetesimals and massive disks, planetesimal fragmentation induces the quickly formation of massive cores only if most of the mass loss in planetesimal collisions is distributed in the bigger fragments. Conclusions. Planetesimal fragmentation seems to play an important role in giant planet formation. The way in which the mass loss in planetesimal collisions is distributed leads to different results, inhibiting or favoring the formation of massive cores. Accepted by A&A http://arxiv.org/pdf/1401.7738

Hot Molecular Circumstellar Disk around Massive Protostar Orion Source I Tomoya Hirota1,2, Mi Kyoung Kim3, Yasutaka Kurono4,5 and Mareki Honma1,2 1 National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan 2 Department of Astronomical Sciences, Graduate University for Advanced Studies, Mitaka, Tokyo 181-8588, Japan 3 Korea Astronomy and Space Science Institute, Hwaam-dong 61-1, Yuseong-gu, Daejeon, 305-348, Republic of Korea 4 Chile Observatory, National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan 5 Joint ALMA Observatory, Alonso de Cordova 3107 Vitacura, Santiago 763-0355, Chile E-mail contact: tomoya.hirota at nao.ac.jp We report new Atacama Large Millimeter/Submillimeter Array (ALMA) observations of a circumstellar disk around Source I in Orion KL, an archetype of massive protostar candidate. We detected two ortho-H2O lines at 321 GHz (102,9-93,6) and 336 GHz (ν2 = 1, 52,3-61,6) for the first time in Source I. The latter one is in vibrationally excited state at the lower state energy of 2939 K, suggesting an evidence of hot molecular gas close to Source I. The integrated intensity map of the 321 GHz line is elongated along the bipolar outflow while the 336 GHz line map is unresolved with a beam size of 0.4 arcsec. Both of these maps show velocity gradient perpendicular to the bipolar outflow. The velocity centroid map of the 321 GHz line implies spatial and velocity structure similar to that of vibrationally-excited SiO masers tracing the root of the outflow emanating from the disk surface. In contrast, the 336 GHz line is most likely emitted from the disk midplane with a diameter of 0.2 arcsec (84 AU) as traced by a radio continuum emission and a dark lane devoid of the vibrationally-excited SiO maser emission. The observed velocity gradient and the spectral profile of the 336 GHz H2O line can be reconciled with a model of an edge-on ring-like structure with an enclosed mass of >7M⊙ and an excitation temperature of >3000 K. The present results provide a further evidence of hot and neutral circumstellar disk rotating around Source I with a diameter of ∼100 AU scale. Accepted by ApJL http://arxiv.org/pdf/1312.0315

26 Discovery and Observations of ASASSN-13db, an EXor Accretion Event on a Low-Mass T Tauri Star Thomas W.-S. Holoien1, Jose L. Prieto2,3, Krzysztof Z. Stanek1,4, Christopher S. Kochanek1,4, B.J. Shappee1, Z. Zhu2,5, A. Sicilia-Aguilar6,7, D. Grupe8, K. Croxall1, J. Adams9, J.D. Simon9, N. Morell10, S.M. McGraw11, R.M. Wagner1,12, U. Basu1,13, J.F. Beacom1,4,14, D. Bersier15, J. Brimacombe16, J. Jencson1, G. Pojmanski17, S.G. Starreld18, D.M. Szczygie l17, C.E. Woodward19 1 Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA 2 Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Peyton Hall, Princeton, NJ 08544, USA 3 Carnegie-Princeton Fellow 4 Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University, 191 W. Woodru Ave., Columbus, OH 43210, USA 5 Hubble Fellow 6 Departamento de F´ısica Te´orica, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Cantoblanco, Madrid, Spain 7 SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS, Scotland, UK 8 Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA 9 Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101, USA 10 Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601, Chile 11 Department of Physics and Astronomy, Ohio University, 251B Clippinger Labs, Athens, OH 45701, USA 12 Large Binocular Telescope Observatory, University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721, USA 13 Grove City High School, 4665 Hoover Road, Grove City, OH 43123, USA 14 Department of Physics, The Ohio State University, 191 W. Woodru Ave., Columbus, OH 43210, USA 15 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK 16 Coral Towers Observatory, Cairns, Queensland 4870, Australia 17 Warsaw University Astronomical Observatory, Al. Ujazdowskie 4, 00-478 Warsaw, Poland 18 School of Earth and Space Exploration, Arizona State University, Box 871404, Tempe, AZ 85287-1404, USA 19 Minnesota Institute for Astrophysics, University of Minnesota, 116 Church St., SE, Minneapolis, MN 55455, USA E-mail contact: tholoien at astronomy.ohio-state.edu We discuss ASASSN-13db, an EXor accretion event on the (YSO) SDSS J051011.01−032826.2 (hereafter SDSSJ0510) discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). Using archival photo- metric data of SDSSJ0510 we construct a pre-outburst spectral energy distribution (SED) and find that it is consistent with a low-mass class II YSO near the Orion star forming region (d∼420 pc). We present follow-up photometric and spectroscopic observations of the source after the ∆V ∼−3.7 mag outburst that began in September 2013. These data −7 −1 indicate an increase in temperature and luminosity consistent with an accretion rate of ∼10 M⊙ yr , three-to-five orders of magnitude greater than in quiescence. Spectroscopic observations show a forest of narrow emission lines dominated by neutral metallic lines from Fe I and some low-ionization lines. The properties of ASASSN-13db are similar to those of the EXor prototype EX Lupi in late 2008 during its strongest observed outburst. Accepted by ApJL http://arxiv.org/pdf/1401.3335

The cometary HII regions of DR 21: Bow shocks or champagne flows or both? K. Immer1,2, C. Cyganowskiy2, M.J. Reid2, and K.M. Menten1 1 Max-Planck-Institut f¨ur Radioastronomie, Auf dem Hgel 69, D-53121 Bonn, Germany 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, 02140, Cambridge, MA, USA E-mail contact: kimmer at mpifr-bonn.mpg.de We present deep Very Large Array H66α radio recombination line (RRL) observations of the two cometary HII regions in DR 21. With these sensitive data, we test the “hybrid” bow shock/champagne flow model previously proposed for the DR 21 HII regions. The ionized gas down the tail of the southern HII region is redshifted by up to ∼30 km s−1

27 with respect to the ambient molecular gas, as expected in the hybrid scenario. The RRL velocity structure, however, reveals the presence of two velocity components in both the northern and southern HII regions. This suggests that the ionized gas is flowing along cone-like shells, swept-up by stellar winds. The observed velocity structure of the well-resolved southern HII region is most consistent with a picture that combines a with stellar motion (as in bow shock models) along a density gradient (as in champagne flow models). The direction of the implied density gradient is consistent with that suggested by maps of dust continuum and molecular line emission in the DR 21 region. Accepted by A&A http://arxiv.org/pdf/1401.1343

The Gaia-ESO Survey: Kinematic structure in the Gamma Velorum cluster R. D. Jeffries1, R. J. Jackson1, M. Cottaar2, S. E. Koposov3, A. C. Lanzafame4, M. R. Meyer2, L. Prisinzano5, S. Randich6, G. G. Sacco6, E. Brugaletta4, M. Caramazza5, F. Damiani5, E. Franciosini6, A. Frasca7, G. Gilmore3, S. Feltzing9, G. Micela5, E. Alfaro8, T. Bensby9, E. Pancino10, A. Recio- Blanco11, P. de Laverny11, J. Lewis3, L. Magrini6, L. Morbidelli6, M. T. Costado8, P. Jofr´e3, A. Klutsch7, K. Lind3, E. Maiorca6 1 Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG, UK 2 Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093, Zurich, Switzerland 3 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, United Kingdom 4 Dipar- timento di Fisica e Astronomia, Sezione Astrofisica, Universit´adi Catania, via S. Sofia 78, 95123, Catania, Italy 5 INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento, Italy 1, 90134, Palermo, Italy 6 INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Florence, Italy 7 INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy 8 Instituto de Astrof´ısica de Andaluc´ıa-CSIC, Apdo. 3004, 18080, Granada, Spain 9 Lund Observatory, Department of Astronomy and Theoretical Physics, Box 43, SE-22100 Lund, Sweden 10 INAF - Osservatorio Astronomico di Bologna, via Ranzani 1, 40127, Bologna, Italy 11 Laboratoire Lagrange (UMR7293), Universit´ede Nice Sophia Antipolis, CNRS,Observatoire de la Cˆote d’Azur, BP 4229,F-06304 Nice cedex 4, France E-mail contact: r.d.jeffries at keele.ac.uk Context. A key science goal of the Gaia-ESO survey (GES) at the VLT is to use the kinematics of low-mass stars in young clusters and star forming regions to probe their dynamical histories and how they populate the field as they become unbound. The clustering of low-mass stars around the massive Wolf-Rayet binary system γ2 Velorum was one of the first GES targets. Aims. To empirically determine the precision of GES data, construct a kinematically unbiased sample of cluster members and characterise their dynamical state. Methods. Targets were selected from colour-magnitude diagrams and intermediate resolution spectroscopy was used to derive radial velocities and assess membership from the strength of the Li i 6708A˚ line. The radial velocity distribution was analysed using a maximum likelihood technique that accounts for unresolved binaries. Results. The GES radial velocity precision is about 0.25 km s−1 and sufficient to resolve velocity structure in the low-mass population around γ2 Vel. The structure is well fitted by two kinematic components with roughly equal numbers of stars; the first has an intrinsic dispersion of 0.34 ± 0.16kms−1, consistent with virial equilibrium. The second has a broader dispersion of 1.60 ± 0.37kms−1 and is offset from the first by ≃ 2kms−1. The first population is older by 1–2Myr based on a greater level of Li depletion seen among its M-type stars and is probably more centrally concentrated around γ2 Vel. Conclusions. We consider several formation scenarios, concluding that the two kinematic components are a bound remnant of the original, denser cluster that formed γ2 Vel, and a dispersed population from the wider Vela OB2 association, of which γ2 Vel is the most massive member. The apparent youth of γ2 Vel compared to the older (≥ 10 Myr) low-mass population surrounding it suggests a scenario in which the massive binary formed in a clustered environment after the formation of the bulk of the low-mass stars. Accepted by Astronomy & Astrophysics http://uk.arxiv.org/pdf/1401.4979

28 Gas Kinematics and Excitation in the Filamentary IRDC G035.39-00.33 I. Jim´enez-Serra1,2, P. Caselli3, F. Fontani4, J. C. Tan5, J. D. Henshaw3, J. Kainulainen6 and A. K. Hernandez7 1 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748, Garching, Germany 2 Harvard-SmithsonianCenter for Astrophysics, 60 Garden St., 02138, Cambridge, MA, USA 3 School of Physics & Astronomy, E.C. Stoner Building, The University of Leeds, Leeds, LS2 9JT, UK 4 Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, Firenze I-50125, Italy 5 Department of Astronomy, University of Florida, Gainesville, FL 32611, USA 6 Max-Planck-Institute for Astronomy, K¨onigstuhl 17, 69117 Heidelberg, Germany 7 Department of Astronomy, University of Wisconsin-Madison, 475 N. Charter Street Madison, WI 53706, USA E-mail contact: ijimenez at eso.org Some theories of dense molecular cloud formation involve dynamical environments driven by converging atomic flows or collisions between preexisting molecular clouds. The determination of the dynamics and physical conditions of the gas in clouds at the early stages of their evolution is essential to establish the dynamical imprints of such collisions, and to infer the processes involved in their formation. We present multi-transition 13CO and C18O maps toward the IRDC G035.39-00.33, believed to be at the earliest stages of evolution. The 13CO and C18O gas is distributed in three filaments (Filaments 1, 2 and 3), where the most massive cores are preferentially found at the intersecting regions between them. The filaments have a similar kinematic structure with smooth velocity gradients of ∼0.4- 0.8 km s−1 pc−1. Several scenarios are proposed to explain these gradients, including cloud rotation, gas accretion along the filaments, global gravitational collapse, and unresolved sub-filament structures. These results are complemented by HCO+, HNC, H13CO+ and HN13C single-pointing data to search for gas infall signatures. The 13CO and C18O gas motions are supersonic across G035.39-00.33, with the emission showing broader linewidths toward the edges of the IRDC. This could be due to energy dissipation at the densest regions in the cloud. The average H2 densities are ∼5000-7000 cm−3, with Filaments 2 and 3 being denser and more massive than Filament 1. The C18O data unveils three regions with high CO depletion factors (fD∼5-12), similar to those found in massive starless cores. Accepted by MNRAS http://arxiv.org/pdf/1401.2347

The VLT-FLAMES Tarantula Survey. XV. VFTS 822: a candidate Herbig B[e] star at low metallicity V.M. Kalari1,2, J.S. Vink1, P.L. Dufton2, C.J. Evans3, P.R. Dunstall3, H. Sana4, J.S. Clark5, L. Ellerbroek6, A. de Koter6, D.J. Lennon7 and W.D. Taylor3 1 Armagh Observatory, College Hill, Armagh, BT61 9DG, UK 2 Department of Physics & Astronomy, Queen’s University Belfast, Belfast, BT71NN, Uk 3 UK Astronomy Technology Centre, Royal Observatory, Edinburgh, Blackford Hill, Edinburgh, EH93HJ, UK 4 ESA/STScI, 3700 San Martin Drive, Baltimore, MD 21218, USA 5 Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes, MK76AA, UK 6 Astronomical Institute Anton Pannekoek, Amsterdam University, Science Park 904, 1098 XH, Amsterdam, Nether- lands 7 European Space Astronomy Centre, Camino bajo del Castillo, Villanueva de la Canada, E-28692 Madrid, Spain E-mail contact: vek at arm.ac.uk We report the discovery of the B[e] star VFTS 822 in the 30 Doradus star-forming region of the , classified by optical spectroscopy from the VLT-FLAMES Tarantula Survey and complementary infrared photometry. VFTS 822 is a relatively low-luminosity (log L = 4.04 ± 0.25 L⊙) B8[e] star. In this Letter, we evaluate the evolutionary status of VFTS 822 and discuss its candidacy as a Herbig B[e] star. If the object is indeed in the pre-main sequence phase, it would present an exciting opportunity to measure mass accretion rates at low metallicity spectroscopically, to understand the effect of metallicity on accretion rates. Accepted by Astronomy & Astrophysics Letters http://arxiv.org/pdf/1401.3149

29 Exocomets in the circumstellar gas disk of HD 172555 F. Kiefer1,2, A. Lecavelier des Etangs1,2, J.-C Augereau3, A. Vidal-Madjar1,2, A.-M. Lagrange3, and H. Beust3 1 CNRS, UMR 7095, Institut d’astrophysique de Paris, 98bis boulevard Arago, F-75014 Paris, France 2 UPMC Univ. Paris 6, UMR 7095, Institut d’Astrophysique de Paris, 98bis boulevard Arago, F-75014 Paris, France 3 UJF-Grenoble 1/CNRS-INSU, Institut de Plan´etologie et dAstrophysique (IPAG) UMR 5274, 38041 Grenoble, France E-mail contact: kiefer at iap.fr The source HD172555 is a young A7V star surrounded by a debris disk with a gaseous component. Here, we present the detection of variable absorption features detected simultaneously in the Ca II K and H doublet lines (at 3,933 and 3,968 A).˚ We identified the presence of these absorption signatures at four different epochs in the 129 HARPS high-resolution spectra gathered between 2004 and 2011. These transient absorption features are most likely due to Falling Evaporating Bodies (FEBs, or exocomets) that produce absorbing gas observed transiting in front of the central star. We also detect a stable Ca II absorption component at the star’s radial velocity. With no corresponding detection in the Na I line, the resulting very low upper limit for the NaI/CaII ratio suggests that this absorption is due to circumstellar gas. Accepted by A&A Letter http://arxiv.org/pdf/1401.1365

The Formation and Evolution of Small Star Clusters Helen Kirk1,2,3, Stella Offner4,2 and Kayla Redmond5,2 1 Origins Institute, McMaster University, Hamilton, ON, Canada 2 Harvard Smithsonian Center for Astrophysics, Cambridge, MA, USA 3 presently Herzberg Astrophysics, National Research Council of Canada 4 Yale University, New Haven, CT, USA 5 University of North Carolina at Asheville, NC, USA E-mail contact: helen.kirk at nrc-cnrc.gc.ca Recent observations show that small, young, stellar groupings of ∼ 10 to 40 members tend of have a centrally-located most massive member, reminiscent of mass segregation seen in large clustered systems. Here, we analyze hydrodynamic simulations which form small clusters and analyze their properties in a manner identical to the observations. We find that the simulated clusters possess similar properties to the observed clusters, including a tendency to exhibit mass segregation. In the simulations, the central location of the most massive member is not due to dynamical evolution, since there is little interaction between the cluster members. Instead, the most massive cluster member appears to form at the center. We also find that the more massive stars in the cluster form at slightly earlier times. Accepted by MNRAS http://arxiv.org/pdf/1401.4510

Spectroscopic characterization and detection of Ethyl Mercaptan in Orion L. Kolesnikov´a1, B. Tercero2, J. Cernicharo2, J.L. Alonso3, A.M. Daly3, B.P. Gordon4, and S.T. Shipman4 1 Grupo de Espectroscop´ıaMolecular (GEM), Edicio Quima, Laboratorios de Espectroscop´ıay Bioespectroscop´ıa, Parque Cient´ıco UVa, Unidad Asociada CSIC, Universidad de Valladolid, 47005 Valladolid, Spain 2 Departamento de Astrof´ısica, Centro de Astrobiolog´ıaCAB, CSIC-INTA, Ctra. de Torrej´on a Ajalvir km 4, 28850 Madrid, Spain 3 Grupo de Espectroscop´ıaMolecular (GEM), Edicio Quima, Laboratorios de Espectroscop´ıay Bioespectroscop´ıa, Parque Cient´ıco UVa, Unidad Asociada CSIC, Universidad de Valladolid, 47005 Valladolid, Spain 4 Division of Natural Sciences, New College of Florida, Sarasota, FL 34243, USA E-mail contact: lucie.kolesnikova at uva.es

30 New laboratory data of ethyl mercaptan, CH3CH2SH, in the millimeter and submillimeter-wave domains (up to 880 GHz) provided very precise values of the spectroscopic constants that allowed the detection of gauche-CH3CH2SH towards Orion KL. 77 unblended or slightly blended lines plus no missing transitions in the range 80–280 GHz support this identification. A detection of methyl mercaptan, CH3SH, in the spectral survey of Orion KL is reported as well. Our column density results indicate that methyl mercaptan is ∼5 times more abundant than ethyl mercaptan in the hot core of Orion KL. Accepted by ApJL http://arxiv.org/pdf/1401.7810

An uncertainty principle for star formation. I. Why galactic star formation relations break down below a certain spatial scale J.M. Diederik Kruijssen1 and Steven N. Longmore2 1 Max-Planck Institut fur Astrophysik, Karl-Schwarzschild-Strae 1, 85748 Garching, Germany 2 Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, United Kingdom E-mail contact: kruijssen at mpa-garching.mpg.de Galactic scaling relations between the (surface densities of) the gas mass and the star formation (SF) rate are known to develop substantial scatter or even change form when considered below a certain spatial scale. We quantify how this behaviour should be expected due to the incomplete statistical sampling of independent star-forming regions. Other included limiting factors are the incomplete sampling of SF tracers from the stellar initial mass function and the spatial drift between gas and stars. We present a simple uncertainty principle for SF, which can be used to predict and interpret the failure of galactic SF relations on small spatial scales. This uncertainty principle explains how the scatter of SF relations depends on the spatial scale and predicts a scale-dependent bias of the gas depletion time-scale when centering an aperture on gas or SF tracer peaks. We show how the scatter and bias are sensitive to the physical size and time-scales involved in the SF process (such as its duration or the molecular cloud lifetime), and illustrate how our formalism provides a powerful tool to constrain these largely unknown quantities. Thanks to its general form, the uncertainty principle can also be applied to other astrophysical systems, e.g. addressing the time-evolution of star-forming cores, protoplanetary discs, or and their nuclei. Accepted by MNRAS http://arxiv.org/pdf/1401.4459

Refined Masses and Distance of the Young Binary Haro 1-14C Jean-Baptiste Le Bouquin1, J.-L. Monin1, Jean-Philippe Berger2, L. Prato3, M. Benisty1, and G. Schaefer4 1 UJF-Grenoble 1/CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble, UMR 5274, Grenoble, France 2 European Southern Observatory, Garching bei M¨unchen, Germany 3 Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA 4 The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023, USA E-mail contact: Jean-Baptiste.Lebouquin at obs.ujf-grenoble.fr We aim to refine the dynamical masses of the individual component of the low-mass pre-main sequence binary Haro 1-14 C. We combine the data of the preliminary orbit presented previously with new interferometric observations obtained with the four 8m telescopes of the Very Large Telescope Interferometer. The derived masses are Ma =0.905±0.043 M⊙ and Mb =0.308 ± 0.011 M⊙ for the primary and secondary components, respectively. This is about five times better than the uncertainties of the preliminary orbit. Moreover, the possibility of larger masses is now securely discarded. The new dynamical distance, d = 96 ± 9 pc, is smaller than the distance to the Ophiuchus core with a significance of 2.6σ. Fitting the spectral energy distribution yields apparent diameters of φa =0.13±0.01 mas andφb =0.10±0.01 mas (corresponding to Ra =1.50 R⊙ and Rb =1.13 R⊙) and a visual extinction of Av ≈ 1.75. Although the revised orbit has a nearly edge-on geometry, the system is unlikely to be a long-period eclipsing binary. The secondary in Haro 1-14C is one of the few low-mass, pre-main sequence stars with an accurately determined dynamical mass and distance.

31 Accepted by Astron. J. http://arxiv.org/pdf/1401.4565

Bondi-Hoyle Accretion in an Isothermal Magnetized Plasma Aaron T. Lee1, Andrew J. Cunningham2, Christopher F. McKee1,3, and Richard I. Klein1,2 1 Department of Astronomy, University of California Berkeley, Berkeley, CA 94720, USA 2 Lawrence Livermore National Laboratory, P.O. Box 808, L-23, Livermore, CA 94550, USA 3 Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA E-mail contact: a.t.lee at berkeley.edu In regions of star formation, protostars and newborn stars accrete mass from their natal clouds. These clouds are threaded by magnetic fields with a strength characterized by the plasma β—the ratio of thermal and magnetic < pressures. Observations show molecular clouds have β ∼ 1, so magnetic fields can play a significant role in the accretion process. We have carried out a numerical study of the effect of large-scale magnetic fields on the rate of accretion onto a uniformly moving point particle from a uniform, non-self-gravitating, isothermal gas. We consider gas moving with sonic Mach numbers of up M ∼ 45, magnetic fields that are either parallel, perpendicular, or oriented 45◦ to the flow, and β as low as 0.01. Our simulations utilize AMR to obtain high spatial resolution where needed; this also allows the simulation boundaries to be far from the accreting object. Additionally, we show our results are independent of our exact prescription for accreting mass in the sink particle. We give simple expressions for the steady-state accretion rate as a function of β, M, and field orientation. Using typical molecular clouds values of M −9 −1 ∼ 5 and β ∼ 0.04 from the literature, our fits suggest a 0.4 M⊙ star accretes ∼4 × 10 M⊙ year , almost a factor of two less than accretion rates predicted by hydrodynamic models. This disparity grows to orders of magnitude for stronger fields and lower Mach numbers. We discuss the applicability of these accretion rates versus accretion rates expected from gravitational collapse, and when a steady state is possible. This reduction in M˙ increases the time required to form stars in competitive accretion models, making such models less efficient. In numerical codes, our results should enable accurate subgrid models of sink particles accreting from magnetized media. Accepted by ApJ http://arxiv.org/pdf/1401.7010

The CO-to-H2 Conversion Factor across the Perseus Molecular Cloud Min-Young Lee1, Snezana Stanimirovi´c1, Mark G. Wolfire2, Rahul Shetty3, Simon C.O. Glover3, Faviola Z. Molina3, and Ralf S. Klessen3 1 Department of Astronomy, University of Wisconsin, Madison, WI 53706, USA 2 Department of Astronomy, University of Maryland, College Park, MD 20742, USA 3 Zentrum f¨ur Astronomie der Universit¨at Heidelberg, Institut f¨ur Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany E-mail contact: lee at astro.wisc.edu

We derive the CO-to-H2 conversion factor, XCO = N(H2)/ICO, across the Perseus molecular cloud on sub- scales by combining the dust-based N(H2) data with the ICO data from the COMPLETE Survey. We estimate an 19 −2 −1 −1 average XCO ∼ 3 × 10 cm K km s and find a factor of ∼3 variations in XCO between the five sub-regions in Perseus. Within the individual regions, XCO varies by a factor of ∼100, suggesting that XCO strongly depends on local conditions in the interstellar medium. We find that XCO sharply decreases at AV < 3 mag but gradually increases at AV > 3 mag, with the transition occurring at AV where ICO becomes optically thick. We compare the N(HI), N(H2), ICO, and XCO distributions with two models of the formation of molecular gas, a one-dimensional photodissociation region (PDR) model and a three-dimensional magnetohydrodynamic (MHD) model tracking both the dynamical and chemical evolution of gas. The PDR model based on the steady state and equilibrium chemistry reproduces our data very well but requires a diffuse halo to match the observed N(HI) and ICO distributions. The MHD model generally matches our data well, suggesting that time-dependent effects on H2 and CO formation are insignificant for an evolved molecular cloud like Perseus. However, we find interesting discrepancies, including a broader range of N(HI), likely underestimated ICO, and a large scatter of ICO at small AV . These discrepancies likely

32 result from strong compressions/rarefactions and density fluctuations in the MHD model. Accepted by ApJ http://arxiv.org/pdf/1401.5117

Simulating star formation in Ophiuchus Oliver Lomax1, Anthony Whitworth1, David Hubber2,3, Dimitris Stamatellos4 and Sefanie Walch5 1 School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, UK 2 University Observatory, Ludwig-Maximilians-University Munich, Scheinerstr.1, D-81679 Munich, Germany 3 Excellence Cluster , Boltzmannstr. 2, D-85748 Garching, Germany 4 Jeremiah Horrocks Institute, University of Central Lancashire, Preston, Lancashire, PR1 2HE, UK 5 Max-Planck-Institut f¨ur Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany E-mail contact: oliver.lomax at astro.cf.ac.uk We have simulated star formation in prestellar cores, using SPH and initial conditions informed by observations of the cores in Ophiuchus. Because the observations are limited to two spatial dimensions plus radial velocity, we cannot infer initial conditions for the collapse of a particular core. However, with a minimum of assumptions (isotropic turbulence with a power-law spectrum, a thermal mix of compressive and solenoidal modes, a critical Bonnor-Ebert density profile) we can generate initial conditions that match, in a statistical sense, the distributions of mass, projected size and aspect ratio, thermal and non-thermal one-dimensional velocity dispersion, observed in Ophiuchus. The time between core-core collisions in Ophiuchus is sufficiently long, that we can simulate single cores evolving is isolation, and therefore we are able to resolve masses well below the opacity limit. We generate an ensemble of 100 cores, and evolve them with no radiative feedback from the stars formed, then with continuous radiative feedback, and finally with episodic radiative feedback. With no feedback the simulations produce too many brown dwarfs, and with continuous feedback too few. With episodic radiative feedback, both the peak of the protostellar mass function (at ∼ 0.2 M⊙ ) and the ratio of H-burning stars to brown dwarfs are consistent with observations. The mass of a star is not strongly related to the mass of the core in which it forms. Low-mass cores (Mcore ∼ 0.1 M⊙ ) tend to collapse into single objects, whereas high-mass cores (Mcore > M⊙ ) usually fragment into several objects with a broad mass range. Accepted by MNRAS http://arxiv.org/pdf/1401.7237

SMA Submillimeter Observations of HL Tau: Revealing a compact molecular outflow Alba M. Lumbreras1,2 and Luis A. Zapata1 1 Centro de Radioastronom´ıay Astrof´ısica, UNAM, M´exico 2 Benem´erita Universidad Aut´onoma de Puebla, Puebla, M´exico E-mail contact: lzapata at crya.unam.mx We present archival high angular resolution (∼2′′) 12CO (3–2) line and continuum submillimeter observations of the young stellar object HL Tau made with the Submillimeter Array (SMA). The 12CO (3–2) line observations reveal the presence of a compact and wide opening angle bipolar outflow with a northeast and southwest orientation (P.A. = 50◦), and that is associated with the optical and infrared jet emanating from HL Tau with a similar orientation. On the other hand, the 850 µm continuum emission observations exhibit a strong and compact source in the position of ◦ HL Tau that has a spatial size of ∼200 × 70 AU with a P.A. = 145 , and a dust mass of around 0.1 M⊙. These physical parameters are in agreement with values obtained recently from millimeter observations. This submillimeter source is therefore related with the disk surrounding HL Tau. Accepted by AJ http://arxiv.org/pdf/1401.0455

33 Synthetic Observations of the Evolution of Starless Cores in a Molecular Cloud Simu- lation: Comparisons with JCMT Data and Predictions for ALMA Steve Mairs1,2, Doug Johnstone2,3,4, Stella S. R. Offner5, and Scott Schnee6 1 Department of Physics & Astronomy, University of Victoria, Victoria, BC, V8P 1A1, Canada 2 National Research Council Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Rd, Victoria, BC, V9E 2E7, Canada 3 Joint Astronomy Centre, 660 North Aohoku Place, University Park, Hilo, HI 96720, USA 4 Department of Physics & Astronomy, University of Victoria, Victoria, BC, V8P 1A1, Canada 5 Department of Astronomy, 260 Whitney Ave, Yale University, New Haven, CT 06511, USA 6 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA E-mail contact: smairs at uvic.ca Interpreting the nature of starless cores has been a prominent goal in star formation for many years. In order to characterise the evolutionary stages of these objects, we perform synthetic observations of a numerical simulation of a turbulent molecular cloud. We find that nearly all cores that we detect are associated with filaments and eventually form protostars. We conclude that observed starless cores which appear Jeans unstable are only marginally larger than their respective Jeans masses (within a factor of 3). We note single dish observations such as those performed with the JCMT appear to miss significant core structure on small scales due to beam averaging. Finally, we predict that interferometric observations with ALMA Cycle 1 will resolve the important small scale structure, which has so far been missed by mm-wavelength observations. Accepted by ApJ http://arxiv.org/pdf/1401.3328

First results from the CALYPSO IRAM-PdBI survey. I. Kinematics of the inner enve- lope of NGC1333-IRAS2A S. Maret1, A. Belloche2, A. J. Maury3, F. Gueth4, Ph. Andr´e5, S. Cabrit6,1, C. Codella7 and S. Bontemps8,9 1 UJF-Grenoble 1 / CNRS-INSU, Institut de Plantologie et d’Astrophysique de Grenoble, UMR 5274, Grenoble, F- 38041, France 2 Max-Planck-Institut fr Radioastronomie, Auf dem Hgel 69, 53121 Bonn, Germany 3 Harvard-Smithsonian Center for Astrophysics, 60 Garden street, Cambridge, MA 02138, USA 4 IRAM, 300 rue de la piscine, 38406 Saint Martin d’Hres, France 5 Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu - CNRS - Universit Paris Diderot, CE-Saclay, F-91191 Gif-sur-Yvette, France 6 LERMA, Observatoire de Paris, CNRS, ENS, UPMC, UCP, 61 Av de l’Observatoire, F-75014 Paris, France 7 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy 8 Universit de Bordeaux, LAB, UMR 5804, F-33270 Floirac, France 9 CNRS, LAB, UMR 5804, F-33270 Floirac, France E-mail contact: sebastien.maret at obs.ujf-grenoble.fr The structure and kinematics of Class 0 protostars on scales of a few hundred AU is poorly known. Recent observations have revealed the presence of Keplerian disks with a diameter of 150-180 AU in L1527-IRS and VLA1623A, but it is not clear if such disks are common in Class 0 protostars. Here we present high-angular-resolution observations of two methanol lines in NGC1333-IRAS2A. We argue that these lines probe the inner envelope, and we use them to study the kinematics of this region. Our observations suggest the presence of a marginal velocity gradient normal to the direction of the outflow. However, the position velocity diagrams along the gradient direction appear inconsistent with a Keplerian disk. Instead, we suggest that the emission originates from the infalling and perhaps slowly rotating envelope, around a central protostar of 0.1 − 0.2 M⊙. If a disk is present, it is smaller than the disk of L1527-IRS, perhaps suggesting that NGC1333-IRAS2A is younger. Accepted by A&A letters http://arxiv.org/pdf/1401.6986

34 Properties of Starless and Prestellar Cores in Taurus Revealed by Herschel SPIRE/PACS Imaging K.A. Marsh1, M.J. Griffin1, P. Palmeirim2, Ph. Andr´e2, J. Kirk3, D. Stamatellos3, D. Ward-Thompson3, A. Roy2, S. Bontemps4,5, J. Di Francesco6, D. Elia7, T. Hill8, V. K¨onyves2,9, F. Motte2, Q. Nguyen- Luong10, N. Peretto1, S. Pezzuto7, A. Rivera-Ingraham11,12, N. Schneider4,5, L. Spinoglio7, and G. White13,14 1 School of Physics and Astronomy, Cardi University, Cardi CF24 3AA, UK 2 Laboratoire AIM, CEA/DSM-CNRS-Universit´eParis Diderot, IRFU / Service d’Astrophysique, C.E. Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France 3 Jeremiah Horrocks Institute for Astrophysics and Supercomputing, University of Central Lancashire, Preston, PR1 2HE, UK 4 Univ. Bordeaux, LAB, UMR 5804, 33270, Floirac, France 5 CNRS, LAB, UMR 5804, 33270, Floirac, France 6 National Research Council of Canada, Hertzberg Institute of Astrophysics, 5071 West Saanich Rd., Victoria, BC, V9E 2E7, Canada 7 Istituto di Astrosica e Planetologia Spaziali - INAF, Via Fosso del Cavaliere 100, I-00133 Roma Italy 8 Joint ALMA Observatory, Alonso de Cordova, 3107, Vitacura, Santiago, Chile 9 Institut d’Astrophysique Spatiale, UMR8617, CNRS/Universit´eParis-Sud 11,91405 Orsay, France 10 Department of Astronomy & Astrophysics, University of Toronto, 50 George Street, Toronto, ON M5S 3H4, Canada 11 Universit´ede Toulouse, UPS-OMP, IRAP, Toulouse, France 12 CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4, France 13 Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK 14 RALSpace, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0NL, UK E-mail contact: ken.marsh at astro.cf.ac.uk The density and temperature structures of dense cores in the L1495 cloud of the Taurus star-forming region are investigated using Herschel SPIRE and PACS images in the 70 µm, 160 µm, 250 µm, 350 µm and 500 µm continuum bands. A sample consisting of 20 cores, selected using spectral and spatial criteria, is analysed using a new maximum likelihood technique, COREFIT, which takes full account of the instrumental point spread functions. We obtain central dust temperatures, T0, in the range 6–12 K and find that, in the majority of cases, the radial density falloff at large radial distances is consistent with the r−2 variation expected for Bonnor-Ebert spheres. Two of our cores exhibit a significantly steeper falloff, however, and since both appear to be gravitationally unstable, such behaviour may have implications for collapse models. We find a strong negative correlation between T0 and peak column density, as expected if the dust is heated predominantly by the interstellar radiation field. At the temperatures we estimate for the core centres, carbon-bearing molecules freeze out as ice mantles on dust grains, and this behaviour is supported here by the lack of correspondence between our estimated core locations and the previously-published positions of H13CO+ peaks. On this basis, our observations suggest a sublimation-zone radius typically ∼104 AU. Comparison + + with previously-published N2H data at 8400 AU resolution, however, shows no evidence for N2H depletion at that resolution. Accepted by MNRAS http://arxiv.org/pdf/1401.7871

First results from the CALYPSO IRAM-PdBI survey. II. Resolving the hot corino in the Class 0 protostar NGC 1333-IRAS2A A. J. Maury1,2,3, A. Belloche4, Ph. Andr´e3, S. Maret5, F. Gueth6, C. Codella7, S. Cabrit8,5, L. Testi2,7,9 and S. Bontemps10 1 Harvard Smithsonian Center for Astrophysics, 60 Garden street, Cambridge MA 02138, USA 2 ESO, Karl Schwarzschild Strasse 2, 85748 Garching bei M¨unchen, Germany 3 Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu - CNRS - Universit´e Paris Diderot, 91191 Gif-sur-Yvette, France 4 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, 53121 Bonn, Germany 5 UJF-Grenoble1/CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble, UMR 5274, Grenoble, France 6 IRAM, 300 rue de la Piscine, 38406 St Martin d’H`eres, France

35 7 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy 8 LERMA, CNRS UMR 8112, Observatoire de Paris, ENS, UPMC, UCP, PSL, F-75014 Paris 9 Excellence Cluster Universe, Boltzmannstr. 2, D-85748, Garching, Germany 10 Universit´ede Bordeaux, LAB, UMR 5804, 33270 Floirac, France 11 CNRS, LAB, UMR 5804, 33270 Floirac, France E-mail contact: amaury at cfa.harvard.edu We investigate the origin of complex organic molecules (COMs) in the gas phase around the low-mass Class 0 protostar NGC1333-IRAS2A, to determine if the COM emission lines trace an embedded disk, shocks from the protostellar jet, or the warm inner parts of the protostellar envelope. In the framework of the CALYPSO (Continuum And Lines in Young ProtoStellar Objects) IRAM Plateau de Bure survey, we obtained large bandwidth spectra at sub-arcsecond resolution towards NGC 1333-IRAS2A. We identify the emission lines towards the central protostar and perform Gaussian fits to constrain the size of the emitting region for each of these lines, tracing various physical conditions and scales. The emission of numerous COMs such as methanol, ethylene glycol, and methyl formate is spatially resolved by our observations. This allows us to measure, for the first time, the size of the COM emission inside the protostellar envelope, finding that it originates from a region of radius 40-100 AU, centered on the NGC 1333-IRAS2A protostellar object. Our analysis shows no preferential elongation of the COM emission along the jet axis, and therefore does not support the hypothesis that COM emission arises from shocked envelope material at the base of the jet. Down to similar sizes, the dust continuum emission is well reproduced with a single power-law envelope model, and therefore does not favor the hypothesis that COM emission arises from the thermal sublimation of grains embedded in a circumstellar disk. Finally, the typical scale ∼60 AU observed for COM emission is consistent with the size of the inner envelope where Tdust > 100 K is expected. Our data therefore strongly suggest that the COM emission traces the hot corino in IRAS2A, i.e., the warm inner envelope material where the icy mantles of dust grains evaporate because they are passively heated by the central protostellar object. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1401.6998

Stellar clusters in the inner Galaxy and their correlation with cold dust emission Esteban F. E. Morales1,2, Friedrich Wyrowski2, Frederic Schuller2,3 and Karl M. Menten2 1 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69117 Heidelberg, Germany 2 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, 53121 Bonn, Germany 3 European Southern Observatory, Alonso de C´ordova 3107, Casilla 19001, Santiago, Chile E-mail contact: morales at mpia.de Context. Stars are born within dense clumps of giant molecular clouds, and constitute young stellar agglomerates known as embedded clusters, which only evolve into bound open clusters under special conditions. Aims. We statistically study all embedded clusters (ECs) and open clusters (OCs) known so far in the inner Galaxy, in particular investigating their interaction with the surrounding molecular environment and the differences in their evolution. Methods. We first compiled a merged list of 3904 clusters from optical and infrared cluster catalogs in the literature, including 75 new (mostly embedded) clusters discovered by us in the GLIMPSE survey. From this list, 695 clusters are within the Galactic range |ℓ| < 606◦ and |b| < 1.5◦ covered by the ATLASGAL survey, which was used to search for correlations with submm dust continuum emission tracing dense molecular gas. We defined an evolutionary sequence of five morphological types: deeply embedded cluster (EC1), partially embedded cluster (EC2), emerging (OC0), OC still associated with a submm clump in the vicinity (OC1), and OC without correlation with ATLASGAL emission (OC2). Together with this process, we performed a thorough literature survey of these 695 clusters, compiling a considerable number of physical and observational properties in a catalog that is publicly available. Results. We found that an OC defined observationally as OC0, OC1, or OC2 and confirmed as a real cluster is equivalent to the physical concept of OC (a bound exposed cluster) for ages in excess of ∼ 16 Myr. Some observed OCs younger than this limit can actually be unbound associations. We found that our OC and EC samples are roughly complete up to ∼ 1 kpc and ∼ 1.8 kpc from the Sun, respectively, beyond which the completeness decays exponentially. Using available age estimates for a few ECs, we derived an upper limit of 3 Myr for the duration of the embedded phase. Combined with the OC age distribution within 3 kpc of the Sun, which shows an excess of young exposed

36 clusters compared to a theoretical fit that considers classical disruption mechanisms, we computed an embedded and young cluster dissolution fraction of 88 ± 8%. This high fraction is thought to be produced by several factors and not only by the classical paradigm of fast gas expulsion. Accepted by A&A http://www.aanda.org/articles/aa/abs/2013/12/aa21626-13/aa21626-13.html

Confronting Outflow-Regulated Cluster Formation Model with Observations Fumitaka Nakamura1 and Zhi-Yun Li2 1 National Astronomical Observatory of Japan 2 University of Virginia, USA E-mail contact: fumitaka.nakamura at nao.ac.jp Protostellar outflows have been shown theoretically to be capable of maintaining supersonic turbulence in cluster- forming clumps and keeping the star formation rate per free-fall time as low as a few percent. We aim to test two basic predictions of this outflow-regulated cluster formation model, namely (1) the clump should be close to virial equilibrium and (2) the turbulence dissipation rate should be balanced by the outflow momentum injection rate, using recent outflow surveys toward 8 nearby cluster-forming clumps (B59, L1551, L1641N, Serpens Main Cloud, Serpens South, ρ Oph, IC 348, and NGC 1333). We find, for almost all sources, that the clumps are close to virial equilibrium and the outflow momentum injection rate exceeds the turbulence momentum dissipation rate. In addition, the outflow kinetic energy is significantly smaller than the clump gravitational energy for intermediate and massive clumps with > 2 Mcl ∼ a few × 10 M⊙, suggesting that the outflow feedback is not enough to disperse the clump as a whole. The number of observed protostars also indicates that the star formation rate per free-fall time is as small as a few percent for all clumps. These observationally-based results strengthen the case for outflow-regulated cluster formation. Accepted by ApJ

Blowing in the wind: The dust wave surrounding σ Ori AB B.B. Ochsendorf1, N.L.J. Cox2, S. Krijt1, F. Salgado1, O. Bern´e4, J.P. Bernard4, L. Kaper3, and A.G.G.M. Tielens1 1 Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA, The Netherlands 2 Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan 200D, bus 2401, 3001 Leuven, Belgium 3 Sterrenkundig Instituut Anton Pannekoek, University of Amsterdam, Science Park 904, P.O. Box 94249, 1090 GE Amsterdam, The Netherlands 4 Universite de Toulouse, UPS-OMP, IRAP, 31028 Toulouse, France E-mail contact: ochsendorf at strw.leidenuniv.nl Observations with the Spitzer Space Telescope and the WISE satellite have revealed a prominent arc-like structure at 50′′ (≈0.1 pc) from the O9.5V/B0.5V system σ Ori AB. We attribute this dust structure to the interaction of radiation pressure from the star with dust carried along by the IC 434 photo-evaporative flow of ionized gas from the dark cloud L1630. We have developed a quantitative model for the interaction of a dusty ionized flow with nearby (massive) stars where radiation pressure stalls dust, piling it up at an appreciable distance (> 0.1 pc), and force it to flow around the star. The model demonstrates that for the conditions in IC 434, the gas will decouple from the dust and will keep its original flow lines. We argue that this dust structure is the first example of a dust wave created by a massive star moving through the interstellar medium. Dust waves (and bow waves) stratify dust grains according to their radiation pressure opacity, which reflects the size distribution and composition of the grain material. Comparison of our model with observations implies that dust-gas coupling through Coulomb interaction is less important than previously thought, challenging our understanding of grain dynamics in hot, ionized regions of space. We describe the difference between dust (and bow) waves and classical bow shocks. We conclude that dust waves and bow waves should be common around stars showing the weak-wind phenomenon and that these structures are best observed at mid-IR to FIR wavelengths. In particular, dust waves and bow waves are most efficiently formed around weak-wind stars moving through a high density medium. Moreover, they provide a unique opportunity to study the direct interaction between a (massive) star and its immediate surroundings.

37 Accepted by A&A http://arxiv.org/pdf/1401.7185

An Alternative Accurate Tracer of Molecular Clouds: The XCI-Factor Stella S. R. Offner1, Thomas G. Bisbas2, Tom A. Bell3, and Serena Viti2 1 Department of Astronomy, Yale University, New Haven, CT 06511, USA 2 Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6B, UK 3 Centro de Astrobiolog´aa (CSIC-INTA), Carretera de Ajalvir, km 4, 28850 Madrid, Spain E-mail contact: stella.offner at yale.edu We explore the utility of CI as an alternative high-fidelity gas mass tracer for Galactic molecular clouds. We evaluate the XCI-factor for the 609 µm carbon line, the analog of the CO X-factor, which is the ratio of the H2 column density to the integrated 12CO(1–0) line intensity. We use 3D-PDR to post-process hydrodynamic simulations of turbulent, star-forming clouds. We compare the emission of CI and CO for model clouds irradiated by 1 and 10 times the average background and demonstrate that CI is a comparable or superior tracer of the molecular gas distribution for column densities up to 6×1023 cm−2. Our results hold for both reduced and full chemical networks. For our fiducial Galactic 20 −2 −1 −1 21 −2 −1 −1 cloud we derive an average XCO of 3.0 × 10 cm K km s and XCI of 1.1 × 10 cm K km s. Accepted by MNRAS Letters http://arxiv.org/pdf/1401.5072

Resolving HD 100546 disc in the mid-infrared: Small inner disc and asymmetry near the gap O. Pani´c1,2, Th. Ratzka3, G.D. Mulders4, C. Dominik5,6, R. van Boekel7, Th. Henning7, W. Jaffe8 and M. Min5 1 Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA , United Kingdom 2 European Southern Observatory, Karl Schwarzschild Strasse 2, D-85748 Garching, Germany 3 Universitaets-Sternwarte Muenchen, Ludwig-Maximilians -Universitaet, Scheinerstr. 1, 81679 Muenchen, Germany 4 Lunar and Planetary Laboratory, The University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721, USA 5 Astronomical Institute Anton Pannekoek, University of Ams terdam, Science Park 904,1098 XH Amsterdam, The Netherlands 6 Department of Astrophysics / IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL N ijmegen, the Netherlands 7 Max-Planck Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg, Germany 8 Leiden Observatory, Leiden University, Niels Bohrweg 2, 23 33 CA Leiden, The Netherlands E-mail contact: opanic at ast.cam.ac.uk A region of roughly half of the solar system scale around the star HD 100546 is largely cleared of gas and dust, in contrast to the bright outer disc. However, some material is observed in the immediate vicinity of the star. We investigate how the dust is distributed within and outside the gap, and constrain the disc geometry with mid-infrared interferometric observations using VLTI/MIDI. With baseline lengths of 40m, our long baseline observations are sensitive to the inner few AU from the star, and we combined them with observations at shorter, 15m baselines, to probe emission beyond the gap at up to 20AU from the star. We modelled the mid-infrared emission using radial temperature profiles. Our model is composed of infinitesimal concentric annuli emitting as black bodies, and it has distinct inner and outer disc components. We derived an upper limit of 0.7AU for the radial size of the inner disc, from our longest baseline data. This small dusty disc is separated from the edge of the outer disc by a large, roughly 10AU wide gap. Our short baseline data place a bright ring of emission at 11+-1AU, consistent with prior observations of the transition region between the gap and the outer disc, known as the disc wall. The inclination and position angle are constrained by our data to i=53±8deg and PA=145±5deg. Compared to the rim and outer disc geometry this suggests co-planarity. Brightness asymmetry is evident in both short and long baseline data, and it is unequivocally discernible from any atmospheric or instrumental effects. The origin of the asymmetry is consistent with the bright disc wall, which we find to be 1-2AU wide. The gap is cleared of micron-sized dust, but we cannot rule out the presence

38 of larger particles and/or perturbing bodies. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1203.6265v3

SDC13 infrared dark clouds: Longitudinally collapsing filaments? N. Peretto1,2, G.A. Fuller3, Ph. Andr´e2, D. Arzoumanian4, V.M. Rivilla5, S. Bardeau6, S. Duarte Puertas7, J.P. Guzman Fernandez7, C. Lenfestey3, G.-X. Li8, F.A. Olguin9,10, B.R. Rock11,12, H. de Villiers13 and J. Williams3 1 School of Physics & Astronomy, Cardiff University, Queens Buildings, The parade, Cardiff CF24 3AA, UK 2 Laboratoire AIM, CEA/DSM-CNRS-Universt´eParis Diderot, IRFU/Service d’Astrophysique, C.E. Saclay, France 3 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK 4 IAS, CNRS (UMR 8617), Universit´eParis-Sud, Bˆatiment 121, 91400 Orsay, France 5 Centro de Astrobiolog´ıa(CSIC-INTA), Ctra. de Torrej´on-Ajalvir, km. 4, E-28850 Torrej´on de Ardoz, Madrid, Spain 6 Institut de Radioastronomie Millim´etrique, 300 Rue de la piscine, F-38406 Saint Martin d’H`eres, France 7 Universidad de Granada, 18071 Granada, Spain 8 Max-Planck Institut f¨ur Radioastronomie, Auf dem H¨ugel, 69, 53121 Bonn, Germany 9 School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK 10 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 11 Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife, Spain 12 Universidad de la Laguna, Dept. Astrofisica, E-38206 La Laguna, Tenerife, Spain 13 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Herts, AL10 9AB, UK E-mail contact: nicolas.peretto at astro.cf.ac.uk Formation of stars is now believed to be tightly linked to the dynamical evolution of interstellar filaments in which they form. In this paper we analyze the density structure and kinematics of a small network of infrared dark fila- ments, SDC13, observed in both dust continuum and molecular line emission with the IRAM 30m telescope. These observations reveal the presence of 18 compact sources amongst which the two most massive, MM1 and MM2, are located at the intersection point of the parsec-long filaments. The dense gas velocity and velocity dispersion observed along these filaments show smooth, strongly correlated, gradients. We discuss the origin of the SDC13 velocity field in the context of filament longitudinal collapse. We show that the collapse timescale of the SDC13 filaments (from 1 Myr to 4 Myr depending on the model parameters) is consistent with the presence of Class I sources in them, and argue that, on top of bringing more material to the centre of the system, collapse could generate additional kinematic support against local fragmentation, helping the formation of starless super-Jeans cores. Accepted by A&A http://adsabs.harvard.edu/abs/2014A\%26A...561A..83P

Probing the gaseous disk of T Tau N with CN 5–4 lines L. Podio1,2, I. Kamp3, C. Codella1, B. Nisini4, G. Aresu5, S. Brittain6, S. Cabrit7,2, C. Dougados8,2, C. Grady9,10, R. Meijerink3,11, G. Sandell12, M. Spaans3, W.-F. Thi2, G. J. White13,14 and P. Woitke15 1 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Florence, Italy 2 UJF-Grenoble 1/CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041, France 3 Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands 4 INAF-Osservatorio Astronomico di Roma, via di Frascati 33, 00040, Monte Porzio Catone, Italy 5 INAF-Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius, Italy 6 Department of Physics & Astronomy, 118 Kinard Laboratory, Clemson University, Clemson, SC 29634, USA 7 LERMA, Observatoire de Paris, UMR 8112 CNRS/INSU, 61 Av. de l’Observatoire, 75014, Paris, France 8 LFCA, UMI 3386, CNRS and Dept. de Astronomia, Universidad de Chile, Santiago, Chile 9 Eureka Scientific, 2452 Delmer, Suite 100, Oakland, CA 96002, USA

39 10 Exoplanets & Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771, USA 11 Leiden Observatory, Leiden University, P.O. Box, NL-2300 RA Leiden, The Netherlands 12 SOFIA-USRA, NASA Ames Research Center, MS 232-12, Building N232, Rm. 146, P.O. Box 1, Moffett Field, CA 94035-0001, USA 13 Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK 14 RALSpace, The Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, UK 15 SUPA, School of Physics and Astronomy, University of St. Andrews, KY16 9SS, UK E-mail contact: lpodio at arcetri.astro.it We present spectrally resolved Herschel/HIFI observations of the young multiple system T Tau in atomic and molecular −1 lines. While CO, H2O, [C II], and SO lines trace the envelope and the outflowing gas up to velocities of 33 km s with respect to systemic, the CN 5–4 hyperfine structure lines at 566.7, 566.9 GHz show a narrow double-peaked profile centered at systemic velocity, consistent with an origin in the outer region of the compact disk of T Tau N. Disk modeling of the T Tau N disk with the thermo-chemical code ProDiMo produces CN line fluxes and profiles +10 consistent with the observed ones and constrain the size of the gaseous disk (Rout = 110−20 AU) and its inclination (i = 25◦±5◦). The model indicates that the CN lines originate in a disk upper layer at 40–110 AU from the star, which is irradiated by the stellar UV field and heated up to temperatures of 50 − 700 K. With respect to previously observed CN 2–1 millimeter lines, the CN 5–4 lines appear to be less affected by envelope emission, due to their larger critical density and excitation temperature. Hence, high-J CN lines are a unique confusion-free tracer of embedded disks, such as the disk of T Tau N. Accepted by ApJ Letters http://arxiv.org/pdf/1401.7791

The strong/weak shock transition in cylindrical and planar blast waves A. C. Raga1, J. Cant´o2, A. Rodr´ıugez-Gonz´alez1, A. G. Petculescu3 1Instituto de Ciencias Nucleares, UNAM, Ap. 70-543, D.F., M´exico 2Instituto de Astronom´ıa, UNAM, M´exico 3Department of Physics, Univ. of Louisiana at Lafayette, USA E-mail contact: raga at nucleares.unam.mx A strong burst of star formation can result in the formation of up to ∼ 103 massive stars, which after a time of ∼ 106 yr will have explosions. Depending on the spatial distribution of the supernovae, their combined effect will produce blast waves with different geometries. In this paper, we derive a solution for supernovae going off in a linear distribution (e.g., along a sector of a spiral arm) and also discuss the case of a planar distribution. Finally, we compare the results obtained for a centrally concentrated, a linear and a planar distribution for the supernovae. Accepted by RMxAA http://www.nucleares.unam.mx/astroplasmas/

No universal minimum-mass extrasolar nebula: Evidence against in-situ accretion of systems of hot super-Earths Sean N. Raymond1,2and Christophe Cossou1,2 1 Univ. Bordeaux, Laboratoire d’Astrophysique de Bordeaux, UMR 5804, F-33270, Floirac, France 2 CNRS, Laboratoire d’Astrophysique de Bordeaux, UMR 5804, F-33270, Floirac, France E-mail contact: rayray.sean at gmail.com It has been proposed that the observed systems of hot super-Earths formed in situ from high-mass disks. By fitting a disk profile to the entire population of Kepler planet candidates, Chiang & Laughlin (2013) constructed a “minimum- mass extrasolar nebula” with surface density profile Σ ∝ r−1.6. Here we use multiple-planet systems to show that it is inconsistent to assume a universal disk profile. Systems with 3–6 low-mass planets (or planet candidates) produce a diversity of minimum-mass disks with surface density profiles ranging from Σ ∝ r−3.2 to Σ ∝ r0.5 (5th-95th percentile).

40 By simulating the transit detection of populations of synthetic planetary systems designed to match the properties of observed super-Earth systems, we show that a universal disk profile is statistically excluded at high confidence. Rather, the underlying distribution of minimum-mass disks is characterized by a broad range of surface density slopes. Models of gaseous disks can only explain a narrow range of slopes (roughly between r0 and r−1.5). Yet accretion of terrestrial planets in a gas-free environment preserves the initial radial distribution of building blocks. The known systems of hot super-Earths must therefore not represent the structure of their parent gas disks and can not have predominantly formed in situ. We instead interpret the diversity of disk slopes as the imprint of a process that re-arranged the solids relative to the gas in the inner parts of protoplanetary disks. A plausible mechanism is inward type 1 migration of Mars- to Earth-mass planetary embryos, perhaps followed by a final assembly phase. Accepted by MNRAS http://arxiv.org/pdf/1401.3743

The Solar Neighborhood. XXXIII. Parallax Results from the CTIOPI 0.9m Program: Trigonometric Parallaxes of Nearby Low-Mass Active and Young Systems Adric R. Riedel1,2, Charlie T. Finch3, Todd J. Henry4, John P. Subasavage5, Wei-Chun Jao4, Lison Malo6, David R. Rodriguez7, Russel J. White4, Douglas R. Gies4, Sergio B. Dieterich4, Jennifer G. Winters4, Cassy L. Davison4, Edmund P. Nelan8, Sarah C. Blunt9,2, Kelle L. Cruz61, 2, Emily L. Rice9,2, Philip A. Ianna10 1 Department of Physics and Astronomy, Hunter College, The City University of New York, 695 Park Avenue, New York, NY 10065, USA 2 Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA 3 Astrometry Department, U.S. Naval Observatory, Washington DC 20392, USA 4 United States Naval Observatory, Flagsta, AZ 86001, USA 5 Department of Physics and Astronomy, Georgia State University, P.O. Box 5060, Atlanta, GA 30302-5060, USA 6 D´epartement de Physique et Observatoire du Mont-Megantic, Universit´ede Montr´eal, C.P. 6128, Succursale Centre- Ville, Montreal, QC, Canada H3C 3J7 7 Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Las Condes, Santiago, Chile 8 Space Telescope Science Institute, USA 9 Department of Engineering Science and Physics, College of Staten Island, 2800 Victory Boulevard, New York, NY 10314, USA 10 Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA E-mail contact: ar494 at hunter.cuny.edu We present basic observational data and association membership analysis for 45 young and active low-mass stellar systems from the ongoing RECONS photometry and astrometry program at the Cerro Tololo Inter-American Obser- vatory. Most of these systems have saturated X-ray emission (log(Lx/Lbol) > −3.5) based on X-ray fluxes from the ROSAT All-Sky Survey, and many are significantly more luminous than main-sequence stars of comparable color. We present parallaxes and proper motions, Johnson-Kron-Cousins VRI photometry, and multiplicity observations from the CTIOPI program on the CTIO 0.9m telescope. To this we add low-resolution optical spectroscopy and line mea- surements from the CTIO 1.5m telescope, and interferometric binary measurements from the Hubble Space Telescope Fine Guidance Sensors. We also incorporate data from published sources: JHKs photometry from the 2MASS point source catalog; X-ray data from the ROSAT All-Sky Survey; and radial velocities from literature sources. Within the sample of 45 systems, we identify 21 candidate low-mass pre-main-sequence members of nearby associations, including members of beta Pictoris, TW Hydrae, Argus, AB Doradus, two ambiguous 30 Myr old systems, and one object that may be a member of the Ursa Major moving group. Of the 21 candidate young systems, 14 are newly identified as a result of this work, and six of those are within 25 of the Sun. Accepted by AJ http://arxiv.org/pdf/1401.0722

41 Trigonometric Parallaxes to Star-Forming Regions within 4 kpc of the A. Sanna1, M. J. Reid2, K. M. Menten1, T. M. Dame2, B. Zhang1, M. Sato1, A. Brunthaler1, L. Moscadelli3 and K. Immer1 1 Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn, Germany 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 3 INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy E-mail contact: asanna at mpifr-bonn.mpg.de We report four trigonometric parallaxes for high-mass star-forming regions within 4 kpc of the Galactic center. These measurements were made with the VLBA as part of the BeSSeL Survey. By associating these sources kinematically with large-scale features in CO and HI longitude-velocity diagrams, we begin to outline some major features of the inner : the Connecting arm, the near and far 3 kpc arms, and the . The Connecting arm in the first lies closer to the Galactic center than the and is offset by the long-bar’s major axis near its leading edge, supporting the presence of an inner Lindblad resonance. Assuming the 3 kpc arms are a continuous physical structure, the relative Galactocentric distance of its near and far sides suggests highly elliptical ◦ streamlines of gas around the bar(s) and a bar corotation radius, rCR > 3.6 kpc. At a Galactic longitude near 10 and a heliocentric distance of about 5 kpc, the and the Norma arm intersect on a face-on view of our Galaxy, while passing at different Galactic latitudes. We provide an accurate distance measurement to the W 31 +0.51 star-forming complex of 4.95−0.43 kpc from the Sun, which associates it with a bright CO feature belonging to the near 3 kpc arm. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1312.3181

Generation of Magnetic Field on the Accretion Disk around a Proto-First-Star Yuki Shiromoto1, Hajime Susa1, and Takashi Hosokawa2 1 Department of Physics, Konan University, Kobe 658-8501, Japan 2 Department of Physics and Research Center for the Early Universe, The University of Tokyo, Tokyo 113-0033, Japan E-mail contact: susa at konan-u.ac.jp The generation process of magnetic field around a proto-first-star is studied. Utilizing the recent numerical result of proto-first-star formation based upon the radiation hydrodynamics simulations, we assess the magnetic field strength generated by the radiative force and the Biermann battery effect. We find that magnetic field of ∼10−9 G is generated on the surface of the accretion disk around the proto-first-star. The field strength on the accretion disk is smaller by two orders of magnitude than the critical value, above which the gravitational fragmentation of the disk is suppressed. Thus, the generated seed magnetic field hardly affect the dynamics of on-site first star formation directly, unless efficient amplification process is taken into consideration. We also find that the generated magnetic field is continuously blown out from the disk on the outflows to the poles, that are driven by the thermal pressure of photoheated gas. The −14 −13 3 −3 strength of the diffused magnetic field in low density regions is ∼10 –10 G at nH=10 cm which could play important roles on the next generation star formation, as well as the seeds of magnetic field exist in present-day universe. Accepted by ApJ http://arxiv.org/pdf/1401.0905

An X-ray and Infrared Survey of the Lynds 1228 Cloud Core Stephen L. Skinner1, Luisa Rebull2, and Manuel G¨udel3 1 CASA, Univ. of Colorado, Boulder, CO, USA 80309-0389, USA 2 Spitzer Science Center / Caltech, M/S 220-6, 1200 East California Blvd., Pasadena, CA 91125, USA 3 Dept. of Astrophysics, Univ. of Vienna, T¨urkenschanzstr. 17, A-1180 Vienna, Austria E-mail contact: stephen.skinner at colorado.edu

42 The nearby Lynds 1228 (L1228) dark cloud at a distance of ∼200 pc is known to harbor several young stars including the driving sources of the giant HH 199 and HH 200 Herbig-Haro outflows. L1228 has been previously studied at optical, infrared, and radio wavelengths but not in X-rays. We present results of a sensitive 37 ks Chandra ACIS- I X-ray observation of the L1228 core region. Chandra detected 60 X-ray sources, most of which are faint (<40 counts) and non-variable. Infrared counterparts were identified for 53 of the 60 X-ray sources using archival data from 2MASS, Spitzer, and WISE. Object classes were assigned using mid-IR colors for those objects with complete photometry, most of which were found to have colors consistent with extragalactic background sources. Seven young stellar object (YSO) candidates were identified including the class I protostar HH 200-IRS which was detected as a faint hard X-ray source. No X-ray emission was detected from the luminous protostar HH 199-IRS. We summarize the X-ray and infrared properties of the detected sources and provide IR spectral energy distribution modeling of high-interest objects including the protostars driving the HH outflows. Accepted by AJ http://arxiv.org/pdf/1401.3285

The dominant epoch of star formation in the Milky Way formed the thick disc Owain Snaith1,2, Misha Haywood1, P. Di Matteo1, Matthew D. Lehnert3, Fran¸coise Combes4, David Katz1, and Ana G´omez1 1 GEPI, Observatoire de Paris, GEPI, CNRS, Universit´eParis Diderot, 5 Place Jules Janssen, 92190 Meudon, France 2 present address: Department of Physics & Astronomy, University of Alabama, Tuscaloosa, Alabama, USA 3 Institut d’Astrophysique de Paris, UMR 7095, CNRS, Universit´ePierre et Marie Curie, 98 bis Bd Arago, Paris, France 4 Observatoire de Paris, LERMA, CNRS, 61 Av de l’Observatoire, 75014, Paris, France E-mail contact: owain.snaith at obspm.fr We report the first robust measurement of the Milky Way star formation history using the imprint left on chemical abundances of long-lived stars. The formation of the Galactic thick disc occurs during an intense star formation phase between 9.0 (z∼1.5) and 12.5 Gyr (z∼4.5) ago and is followed by a dip (at z∼1.1) lasting about 1 Gyr. Our results imply that the thick disc is as massive as the Milky Way’s thin disc, suggesting a fundamental role of this component in the genesis of our Galaxy, something that had been largely unrecognized. This new picture implies that huge quantities of gas necessary to feed the building of the thick disc must have been present at these epochs, in contradiction with the long-term infall assumed by chemical evolution models in the last two decades. These results allow us to fit the Milky Way within the emerging features of the evolution of disc galaxies in the early Universe. Accepted by ApJL http://arxiv.org/pdf/1401.1835

CSI 2264: Characterizing Accretion-Burst Dominated Light Curves for Young Stars in NGC 2264 John Stauffer1, Ann Marie Cody1, Annie Baglin2, Silvia Alencar3, Luisa Rebull1, Lynne A. Hillenbrand4, Laura Venuti5, Neal J. Turner6, John Carpenter4, Peter Plavchan7, Krzysztof Findeisen4, Sean Carey1, Susan Terebey8, Mar´ıa Morales-Calder´on9, Jerome Bouvier5, Giusi Micela10, Ettore Flaccomio10, In- seok Song11, Rob Gutermuth12, Lee Hartmann13, Nuria Calvet13, Barbara Whitney14, David Barrado9, Frederick J. Vrba15, Kevin Covey16, William Herbst17, Gabor Furesz18, Suzanne Aigrain19, Fabio Favata20 1Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125, USA, 2LESIA, Observatoire de Paris- Meudon, 5 place Jules Janssen, 92195, Meudon, France, 3Departamento de F´ısica – ICEx – UFMG, Av. Antˆonio Carlos, 6627, 30270-901, Belo Horizonte, MG, Brazil, 4Astronomy Department, California Institute of Technology, Pasadena, CA 91125, USA, 5UJF-Grenoble 1 / CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Greno- ble (IPAG) UMR 5274, Grenoble, F-38041, France, 6Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA, 7Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA, 8Department of Physics and Astronomy, 5151 State University Drive, California State University at

43 Los Angeles, Los Angeles, CA 90032, USA, 9Centro de Astrobiolog´ıa, Dpto. de Astrof´ısica, INTA-CSIC, PO BOX 78, E-28691, ESAC Campus, Villanueva de la Ca˜nada, Madrid, Spain, 10INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134, Palermo, Italy, 11Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602-2451, USA, 12Five College Astronomy Department, Smith College, Northampton, MA 01063, USA, 13Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105, USA, 14Astronomy Department, University of Wisconsin- Madison, 475 N. Charter St., Madison, WI 53706, USA, 15U.S. Naval Observa- tory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001, USA, 16Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA, 17Astronomy Department, Wesleyan University, Middletown, CT 06459, USA, 18Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA, 19Sub-department of As- trophysics, Departmentof Physics, University of Oxford, Oxford OX1 3RH, 20European Space Agency, 8-10 rue Mario Nikis, F-75738 Paris Cedex 15, France E-mail contact: [email protected] Based on more than four weeks of continuous high cadence photometric monitoring of several hundred members of the young cluster NGC 2264 with two space telescopes, NASA’s Spitzer and the CNES CoRoT (Convection, Rotation, and planetary Transits), we provide high quality, multi-wavelength light curves for young stellar objects (YSOs) whose optical variability is dominated by short duration flux bursts, which we infer are due to enhanced mass accretion rates. These light curves show many brief – several hour to one day – brightenings at optical and near-infrared (IR) wavelengths with amplitudes generally in the range 5-50% of the quiescent value. Typically, a dozen or more of these bursts occur in a thirty day period. We demonstrate that stars exhibiting this type of variability have large (UV) excesses and dominate the portion of the u − g vs. g − r color-color diagram with the largest UV excesses. These stars also have large Hα equivalent widths, and either centrally peaked, lumpy Hα emission profiles or profiles with blue-shifted absorption dips associated with disk or stellar winds. Light curves of this type have been predicted for stars whose accretion is dominated by Rayleigh-Taylor instabilities at the boundary between their magnetosphere and inner circumstellar disk, or where magneto-rotational instabilities modulate the accretion rate from the inner disk. Amongst the stars with the largest UV excesses or largest Hα equivalent widths, light curves with this type of variability greatly outnumber light curves with relatively smooth sinusoidal variations associated with long-lived hot spots. We provide quantitative statistics for the average duration and strength of the accretion bursts and for the fraction of the accretion luminosity associated with these bursts. Accepted by Astron. J. http://web.ipac.caltech.edu/staff/amc/staufferetal2014.pdf http://arxiv.org/pdf/1401.6600

6.7 GHz methanol maser variability in Cepheus A M. Szymczak1, P. Wolak1 and A. Bartkiewicz1 1 Centre for Astronomy, Nicolaus Copernicus University, 87-100 Torun, Poland E-mail contact: msz at astro.umk.pl 6.7 GHz methanol maser emission from the well-studied star-forming region Cepheus A was monitored with the Torun 32 m radio telescope. We found synchronized and anticorrelated changes of the flux density of the two blueshifted and one redshifted maser features for ∼30 per cent of 1340d of our observations. Two of those features exhibited high amplitude flux density variations with periods of 84−87 d over the last 290 d interval of the monitoring. We also report on two flares of emission at two different redshifted velocities completely covered during the whole outburst. These flare events lasted 510−670 d and showed a very rapid linear rise and slow exponential decline, which may be caused by variability of the seed flux density. The flux density of the two strongest features dropped by a factor of 2−5 on a time-scale ∼22 yr, while other features have not changed significantly during this period, but showed strong < variability on time-scales ∼5 yr. Accepted by MNRAS http://arxiv.org/pdf/1401.7556

44 Kinematic structure of massive star-forming regions - I. Accretion along filaments J. Tackenberg1, H. Beuther1, Th. Henning1, H. Linz1, T. Sakai2, S. E. Ragan1, O. Krause1,M. Nielbock1, M. Hennemann3, J. Pitann1 and A. Schmiedecke4 1 Max-Planck-Institut f¨ur Astronomie (MPIA), K¨onigstuhl 17, 69117 Heidelberg, Germany 2 Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182- 8585, Japan 3 AIM Paris-Saclay, CEA/DSM/IRFU – CNRS/INSU – Universit´eParis Diderot, CEA Saclay, 91191 Gif-sur-Yvette cedex, France 4 Universit¨at zu K¨oln, Z¨ulpicher Str. 77, 50937, K¨oln, Germany E-mail contact: jochen.tackenberg at koeln.de The mid- and far-infrared view on high-mass star formation, in particular with the results from the Herschel space observatory, has shed light on many aspects of massive star formation. However, these continuum studies lack kinematic information. We study the kinematics of the molecular gas in high-mass star-forming regions. We complemented the PACS and SPIRE far-infrared data of 16 high-mass star-forming regions from the Herschel key + + project EPoS with N2H molecular line data from the MOPRA and Nobeyama 45m telescope. Using the full N2H hyperfine structure, we produced column density, velocity, and linewidth maps. These were correlated with PACS 70µm images and PACS point sources. In addition, we searched for velocity gradients. For several regions, the data suggest that the linewidth on the scale of clumps is dominated by outflows or unresolved velocity gradients. IRDC 18454 and G11.11 show two velocity components along several lines of sight. We find that all regions with a diameter larger than 1 pc show either velocity gradients or fragment into independent structures with distinct velocities. The velocity profiles of three regions with a smooth gradient are consistent with gas flows along the filament, suggesting accretion flows onto the densest regions. We show that the kinematics of several regions have a significant and complex velocity structure. For three filaments, we suggest that gas flows toward the more massive clumps are present. Accepted by A&A

60Fe-60Ni chronology of core formation in Mars Haolan Tang1 and Nicolas Dauphas1 1 Origins Lab, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA E-mail contact: haolantang at ucla.edu The timescales of accretion, core formation, and magmatic differentiation in planetary bodies can be constrained using extinct radionuclide systems. Experiments have shown that Ni becomes more siderophile with decreasing pressure, which is reflected in the progressively higher Fe/Ni ratios in the mantles of Earth, Mars and Vesta. Mars formed rapidly 60 60 and its mantle has a high Fe/Ni ratio, so the Fe- Ni decay system (t1/2=2.62 Myr) is well suited to establish the timescale of core formation in this object. We report new measurements of 60Ni/58Ni ratios in bulk SNC/martian (Shergotty-Nakhla-Chassigny) meteorites and chondrites. The difference in ǫ60Ni values between SNC meteorites and the building blocks of Mars assumed to be chondritic (55% ordinary chondrites +45% enstatite chondrites) is +0.028 ± 0.023 (95% confidence interval). Using a model of growth of planetary embryo, this translates into a time +1.7 for Mars to have reached ∼44% of its present size of 1.9−0.8 Myr with a strict lower limit of 1.2 Myr after solar system formation, which agrees with a previous estimate based on 182Hf-182W systematics. The presence of Mars when planetesimals were still being formed may have influenced the formation of chondrules through bow shocks or by inducing collisions between dynamically excited planetesimals. Constraints on the growth of large planetary bodies are scarce and this is a major development in our understanding of the chronology of Mars. Accepted by Earth and Planetary Science Letters http://arxiv.org/pdf/1401.1830

45 Accretion of Solid Materials onto Circumplanetary Disks from Protoplanetary Disks Takayuki Tanigawa1, Akito Maruta2, and Masahiro N. Machida2 1 Institute of Low Temperature Science, Hokkaido University, Sapporo, 060-0819, Japan 2 Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 812-8581, Japan E-mail contact: tanigawa at pop.lowtem.hokudai.ac.jp We investigate accretion of solid materials onto circumplanetary disks from heliocentric orbits rotating in protoplan- etary disks, which is a key process for the formation of regular satellite systems. In the late stage of gas-capturing phase of giant planet formation, the accreting gas from protoplanetary disks forms circumplanetary disks. Since the accretion flow toward the circumplanetary disks affects the particle motion through gas drag force, we use hydrody- namic simulation data for the gas drag term to calculate the motion of solid materials. We consider wide range of size for the solid particles (10−2–106 m), and find that the accretion efficiency of the solid particles peaks around 10m-sized particles because energy dissipation of drag with circum-planetary disk gas in this size regime is most ef- fective. The efficiency for particles larger than 10m size becomes lower because gas drag becomes less effective. For particles smaller than 10m, the efficiency is lower because the particles are strongly coupled with the back-ground gas flow, which prevent particles from accretion. We also find that the distance from the planet where the particles are captured by the circumplanetary disks is in a narrow range and well described as a function of the particle size. Accepted by ApJ http://arxiv.org/pdf/1401.4128

Molecular gas properties of the giant molecular cloud complexes in the arms and inter- arms of the NGC 6946 Selcuk Topal1, Estelle Bayet1, Martin Bureau1, Timothy A. Davis2 and Wilfred Walsh3 1 Sub-department of Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH 2 European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Muenchen, Germany 3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA E-mail contact: selcuk.topal at astro.ox.ac.uk Combining observations of multiple CO lines with radiative transfer modeling is a very powerful tool to investigate the physical properties of the molecular gas in galaxies. Using new observations as well as literature data, we provide the most complete CO ladders ever generated for eight star-forming regions in the spiral arms and inter-arms of the spiral galaxy NGC 6946, with observations of the CO(1-0), CO(2-1), CO(3-2), CO(4-3), CO(6-5), 13CO(1-0) and 13CO(2-1) transitions. For each region, we use the large velocity gradient assumption to derive beam-averaged molecular gas physical properties, namely the gas kinetic temperature (TK), H2 number volume density (n(H2)) and CO number column density (N(CO)). Two complementary approaches are used to compare the observations with the model predictions: χ2 minimisation and likelihood. The physical conditions derived vary greatly from one region to the next: 2.3 7.0 −3 15.0 19.3 −2 TK = 10–250 K, n(H2)= 10 –10 cm and N(CO)= 10 –10 cm . The spectral line energy distribution (SLED) of some of these extranuclear regions indicates a star-formation activity that is more intense than that at the centre of our own Milky Way. The molecular gas in regions with a large SLED turnover transition (Jmax > 4) is hot but tenuous with a high CO column density, while that in regions with a low SLED turnover transition (Jmax ≤ 4) is cold but dense with a low CO column density. We finally discuss and find some correlations between the physical properties of the molecular gas in each region and the presence of young indicators (supernova remnants, H II regions, H I holes, etc). Accepted by MNRAS http://adsabs.harvard.edu/abs/2014MNRAS.437.1434T

High-Resolution Submillimeter and Near-Infrared Studies of the Transition Disk around Sz 91 Takashi Tsukagoshi1, Munetake Momose1, Jun Hashimoto5, Tomoyuki Kudo2, Sean Andrews4, Masao Saito2, Yoshimi Kitamura3, Nagayoshi Ohashi2, David Wilner4, Ryohei Kawabe2, Lyu Abe7, Eiji

46 Akiyama2, Wolfgang Brandner8, Timothy D. Brandt9, Joseph Carson10, Thayne Currie28, Sebastian E. Egner11, Miwa Goto12, Carol Grady13, Olivier Guyon11, Yutaka Hayano11, Masahiko Hayashi2, Saeko Hayashi11, Thomas Henning8, Klaus W. Hodapp14, Miki Ishii2, Masanori Iye2, Markus Janson15, Ryo Kandori2, Gillian R. Knapp15, Nobuhiko Kusakabe2, Masayuki Kuzuhara2,16, Jungmi Kwon27, Mike McElwain17, Taro Matsuo18, Satoshi Mayama27, Shoken Miyama19, Jun-ichi Morino2, Amaya Moro- Mart´ın20, Tetsuro Nishimura11, Tae-Soo Pyo11, Eugene Serabyn21, Takuya Suenaga27, Hiroshi Suto2, Ryuji Suzuki2, Yasuhiro Takahashi6, Hideki Takami2, Michihiro Takami22, Naruhisa Takato11, Hiroshi Terada11, Christian Thalmann23, Daigo Tomono11, Edwin L. Turner9, Tomonori Usuda11, Makoto Watanabe24, John P. Wisniewski25, Toru Yamada26 and Motohide Tamura2,6 1 College of Science, Ibaraki University, Bunkyo 2-1-1, Mito 310-8512, Japan, 2 National Astronomical Observatory Japan(NAOJ), Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan, 3 Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510, Japan, 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA, 5 Department of Physics and Astronomy, The University of Oklahoma, 440 W. Brooks St. Norman, OK 73019, USA, 6 School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan, 7 Lboratoire Lagrange (UMR 7293), Universit´ede Nice-Sophia Antipolis, CNRS, Observatoire de la Cˆote d’Azur, 28 avenue Valrose, 06108 Nice Cedex 2, France, 8 Max Planck Institute for Astronomy, K¨onigstuhl 17, 69117 Heidelberg, Germany, 9 Department of Astrophysical Sciences, Princeton University, Peyton Hall, Ivy Lane, Princeton, NJ 08544, USA, 10 Department of Physics and Astronomy, College of Charleston, 58 Coming St., Charleston, SC 29424, USA, 11 Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720, USA, 12 Universit¨ats-Sternwarte M¨unchen, Ludwig-Maximilians-Universit¨at, Scheinerstr. 1, 81679 M¨unchen, Germany, 13 Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771 USA, 14 Institute for Astronomy, University of Hawaii, 640 N. A’ohoku Place, Hilo, HI 96720, USA, 15 Department of Astrophysical Sciences, Princeton University, Peyton Hall, Ivy Lane, Princeton, NJ 08544, USA, 16 Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan, 17 Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771 USA, 18 Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto, Kyoto 606-8502, Japan, 19 Hiroshima University, 1-3-2, Kagamiyama, Higashihiroshima, Hiroshima 739-8511, Japan, 20 Department of Astrophysics, CAB-CSIC/INTA, 28850 Torrej´on de Ardoz, Madrid, Spain, 21 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 171-113, USA, 22 Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan, 23 Astronomical Institute ”Anton Pannekoek”, University of Amsterdam, Postbus 94249, 1090 GE, Amsterdam, The Netherlands, 24 Department of Cosmosciences, Hokkaido University, Kita- ku, Sapporo, Hokkaido 060-0810, Japan, 25 Department of Astronomy, University of Washington, Box 351580 Seattle, WA 98195, USA, 26 Astronomical Institute, Tohoku University, Aoba-ku, Sendai, Miyagi 980-8578, Japan, 27 The Graduate University for Advanced Studies (SOKENDAI), Shonan International Village, Hayama-cho, Miura-gun, Kanagawa 240-0193, Japan, 28 Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street M5S 3H4, Toronto Ontario, Canada E-mail contact: ttsuka at mx.ibaraki.ac.jp To reveal the structures of a transition disk around a young stellar object in Lupus, Sz 91, we have performed aperture synthesis 345 GHz continuum and CO(3–2) observations with the Submillimeter Array (∼1′′–3′′ resolution), and high- resolution imaging of polarized intensity at the Ks-band by using the HiCIAO instrument on the Subaru Telescope (0.25′′ resolution). Our observations successfully resolved the inner and outer radii of the dust disk to be 65 AU and 170 AU, respectively, which indicates that Sz 91 is a transition disk source with one of the largest known inner holes. −3 The model fitting analysis of the spectral energy distribution reveals an H2 mass of 2.4 × 10 M⊙ in the cold (T <30 K) outer part at 65 3 × 10 M⊙) of hot (T ∼180 K) dust possibly remains inside the inner hole of the disk. The structure of the hot component could be interpreted as either an unresolved self-luminous companion body (not directly detected in our observations) or a narrow ring inside the inner hole. Significant CO(3–2) emission with a velocity gradient along the major axis of the dust disk is concentrated on the Sz 91 position, suggesting a rotating gas disk with a radius of 420 AU. The Sz 91 disk is possibly a rare disk in an evolutionary stage immediately after the formation of protoplanets because of the large inner hole and the lower disk mass than other transition disks studied thus far. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1402.1538

47 The AKARI Far-Infrared Surveyor young stellar Q1 object catalog L. Viktor Toth1,2, Gabor Marton1,3, Sarolta Zahorecz1,2, Lajos G. Balazs1,3, Munetaka Ueno4, Motohide Tamura5,6, Akiko Kawamura5, Zoltan T. Kiss2 and Yoshimi Kitamura4 1 Department of Astronomy of the Lorand Eotvos University, Pazmany Peter setany 1/a, 1117 Budapest, Hungary 2 Max-Planck-Institut fur Astronomie, Konigstuhl 17, D-69117 Heidelberg, Germany 3 Konkoly Observatory of the Hungarian Academy of Sciences, Konkoly Thege Mikl os ut 15-17, H-1121 Budapest, Hungary 4 Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara 229-8510, Japan 5 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 6 The Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan E-mail contact: l.v.toth at astro.elte.hu, marton.gabor at csfk.mta.hu We demonstrate the use of the AKARI all-sky survey photometric data in the study of galactic star formation. Our aim was to select young stellar objects (YSOs) in the AKARI Far-Infrared Surveyor (FIS) Bright Source Catalogue. We used AKARI/FIS and Wide-field Infrared Survey Explorer (WISE) data to derive mid- and far-infrared colors of YSOs. Classification schemes based on quadratic discriminant analysis (QDA) have been given for YSOs and the training catalog for QDA was the whole-sky selection of previously known YSOs (i.e., listed in the SIMBAD database). A new catalog of AKARI FIS YSO candidates including 44001 sources has been prepared; the reliability of the classification is over 90%, as tested in comparison to known YSOs. As much as 76% of our YSO candidates are from previously uncatalogued types. The vast majority of these sources are Class I and II types according to the Lada classification. The distribution of AKARI FIS YSOs is well correlated with that of the galactic ISM; local over-densities were found on infrared loops and towards the cold clumps detected by Planck. Accepted by Publ. Astron. Soc. Japan

Ionization compression impact on dense gas distribution and star formation, Probability density functions around H II regions as seen by Herschel P. Tremblin1,2, N. Schneider3, V. Minier1 and et al.1,2,3 1 Laboratoire AIM Paris-Saclay (CEA/Irfu - Uni. Paris Diderot - CNRS/INSU, Centre d’´etudes de Saclay, 91191 Gif-Sur-Yvette, France 2 Astrophysics Group, University of Exeter, EX4 4QL Exeter, UK 3 Univ. Bordeaux, LAB, UMR 5804, F-33270, Floirac, France E-mail contact: tremblin at astro.ex.ac.uk Aims. The expansion of hot ionized gas from an H ii region into a molecular cloud compresses the material and leads to the formation of dense continuous layers as well as pillars and globules in the interaction zone. Herschel imaging in the far-infrared (FIR) confirmed the presence of these dense features - potential sites of star-formation - at the edges of H ii regions. This feedback should also impact the probability distribution function (PDF) of the column density around the ionized gas. We aim to quantify this effect and discuss its potential link to the Core and Initial Mass Function (CMF/IMF). Methods. We used in a systematic way Herschel column density maps of several regions observed within the HOBYS key program: M16, the Rosette and Vela C molecular cloud, and the RCW 120 H ii region. We computed the PDFs in concentric disks around the main ionizing sources, determined their properties, and discuss the effect of ionization pressure on the distribution of the column density. Results. We fitted the column density PDFs of all clouds with two lognormal distributions, since they present a ’double-peak’ or enlarged shape in the PDF. Our interpretation is that the lowest part of the column density distribution describes the turbulent molecular gas while the second peak corresponds to a compression zone induced by the expansion of the ionized gas into the turbulent molecular cloud. Such a double-peak is not visible for all clouds associated with ionization fronts but depends on the relative importance of ionization-pressure and turbulent ram pressure. A power-law tail is present for higher column densities, generally ascribed to the effect of gravity. The condensations at the edge of the ionized gas have a steep compressed radial profile, sometimes recognizable in the flattening of the power-law tail. This could lead to an unambiguous criterion able to disentangle triggered from pre-existing star formation. Conclusions. In the context of the gravo-turbulent scenario for the origin of the CMF/IMF, the double peaked/enlarged shape of the PDF

48 may impact the formation of objects at both the low-mass and the high-mass end of the CMF/IMF. In particular a broader PDF is required by the gravo-turbulent scenario to fit properly the IMF with a reasonable initial Mach number for the molecular cloud. Since other physical processes (e.g. the equation of state and the variations among the core properties) have already been suggested to broaden the PDF, the relative importance of the different effects remains an open question. Accepted by A&A http://arxiv.org/pdf/1401.7333

Warm formaldehyde in the Oph IRS 48 transitional disk Nienke van der Marel1, Ewine F. van Dishoeck1,2, Simon Bruderer2 and Tim A. van Kempen1 1 Leiden Observatory, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands 2 MPE, Giessenbachstrasse 1, D-85748 Garching, Germany E-mail contact: nmarel at strw.leidenuniv.nl

Simple molecules like H2CO and CH3OH in protoplanetary disks are the starting point for the production of more complex organic molecules. So far, the observed chemical complexity in disks has been limited due to freeze out of molecules onto grains in the bulk of the cold outer disk. Complex molecules can be studied more directly in transitional disks with large inner holes, as these have a higher potential of detection, through UV heating of the outer disk and the directly exposed midplane at the wall.We use Atacama Large Millimeter/submillimeter Array (ALMA) Band 9 (∼680 GHz) line data of the transitional disk Oph IRS 48, previously shown to have a large dust trap, to search for complex molecules in regions where planetesimals are forming. We report the detection of the H2CO 9(1,8)–8(1,7) line at 674 GHz, which is spatially resolved as a semi-ring at ∼ 60 AU radius centered south from the star. The inferred H2CO abundance is ∼ 10−8 derived by combining a physical disk model of the source with a non-LTE excitation calculation. Upper limits for CH3OH lines in the same disk give an abundance ratio H2CO/CH3OH >0.3, which points to both ice 13 + formation and gas-phase routes playing a role in the H2CO production. Upper limits on the abundances of H CO , CN and several other molecules in the disk are also derived and found to be consistent with full chemical models. The detection of the H2CO line demonstrates the start of complex organic molecules in a planet-forming disk. Future ALMA observations should be able to push down the abundance detection limits of other molecules by 1–2 orders of magnitude and test chemical models of organic molecules in (transitional) disks. Accepted by A&A http://arxiv.org/pdf/1402.0392

On the role of the H2 ortho:para ratio in gravitational collapse during star formation Neil Vaytet1, Kengo Tomida2, and , Gilles Chabrier1,3 1 Ecole´ Normale Sup´erieure de Lyon, CRAL, UMR CNRS 5574, Universit´eLyon I, 46 Allee d’Italie, 69364 Lyon Cedex 07, France 2 Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA 3 School of Physics, University of Exeter, Exeter, EX4 4QL, UK E-mail contact: neil.vaytet at ens-lyon.fr

Hydrogen molecules (H2) come in two forms in the interstellar medium, ortho- and para-hydrogen, corresponding to the two different spin configurations of the two hydrogen atoms. The relative abundances of the two flavours in the interstellar medium are still very uncertain, and this abundance ratio has a significant impact on the thermal properties of the gas. In the context of star formation, theoretical studies have recently adopted two different strategies when considering the ortho:para ratio (OPR) of H2 molecules; the first considers the OPR to be frozen at 3:1 while the second assumes that the species are in thermal equilibrium. As the OPR potentially affects the protostellar cores which form as a result of the gravitational collapse of a dense molecular cloud, the aim of this paper is to quantify precisely what role the choice of OPR plays in the properties and evolution of the cores. We used two different ideal gas equations of state for a hydrogen and helium mix in a radiation hydrodynamics code to simulate the collapse of a dense cloud and the formation of the first and second Larson cores; the first equation of state uses a fixed OPR of 3:1 while the second assumes thermal equilibrium. Simulations using an equilibrium ratio collapse faster at early times

49 and show noticeable oscillations around hydrostatic equilibrium, to the point where the core expands for a short time right after its formation before resuming its contraction. In the case of a fixed 3:1 OPR, the core’s evolution is a lot smoother. The OPR was however found to have little impact on the size, mass and radius of the two Larson cores. We conclude that if one is solely interested in the final properties of the cores when they are formed, it does not matter which OPR is used. On the other hand, if one’s focus lies primarily in the evolution of the first core, the choice of OPR becomes important. Accepted by A&A http://arxiv.org/pdf/1401.4299

Southern class I methanol masers at 36 and 44 GHz M.A. Voronkov1,2,3, J.L. Caswell1, S.P. Ellingsen3, J.A. Green4 and S.L. Breen1,3 1 Australia Telescope National Facility, CSIRO Astronomy and Space Science, PO Box 76, Epping, NSW 1710, Australia 2 Astro Space Centre, Profsouznaya st. 84/32, 117997 Moscow, Russia 3 School of Mathematics and Physics, University of Tasmania, GPO Box 252-37, Hobart, Tasmania 7000, Australia 4 SKA Organisation, Jodrell Bank Observatory, Lower Withington, Macclesfield, Cheshire SK11 9DL, UK E-mail contact: Maxim.Voronkov at csiro.au The Australia Telescope Compact Array (ATCA) has been used for high angular resolution imaging of 71 southern class I methanol maser sources quasi-simultaneously at 36 and 44 GHz. The data reveal a high level of morphological and kinematical complexity, and allow us to demonstrate associations, at arcsecond precision, of the class I maser emission with outflows, expanding Hii regions, dark clouds, shocks traced by the 4.5-µm emission and 8.0-µm filaments. More than 700 maser component features were found at each of the two methanol transitions, but with only 23 per cent recognisable at both transitions; the morphology of class I emission is much better revealed by our survey of both transitions, compared with either one alone. We found that the number of masers falls exponentially with the projected linear distance from the associated class II 6.7-GHz methanol maser. This distribution has a scale of 263±15 mpc, irrespective of the transition. The class I masers associated with OH masers were found to have a tendency to be more spread out, both spatially and in the velocity domain. This is consistent with the expectation that such sources are more evolved. Apart from a small number of high-velocity components (which are largely blue-shifted and predominantly seen at 36 GHz), the velocity distribution was found to be Gaussian, peaking near the systemic velocity of the region, which had been estimated as the middle of the velocity interval of the associated class II methanol maser at 6.7 GHz. The mean indicated a small, but significant blue shift asymmetry of −0.57 km s−1 (uncertainties are 0.06 and 0.07 km s−1 for the 36- and 44-GHz masers, respectively) with respect to the 6.7-GHz masers. The standard deviation of the velocity distribution was found to be 3.65±0.05 and 3.32±0.07 km s−1 for the 36- and 44-GHz masers, respectively. We also suggest a refined rest frequency value of 36169.238±0.011 MHz for the 4−1−30 E methanol transition. Accepted by MNRAS http://arxiv.org/pdf/1401.5179

Hierarchical fragmentation and differential star formation in the Galactic ”Snake”: in- frared dark cloud G11.11-0.12 Ke Wang1,2,3,4, Qizhou Zhang2, Leonardo Testi1,5,6, Floris van der Tak3,7, Yuefang Wu4, Huawei Zhang4, Thushara Pillai8, Friedrich Wyrowski9, Sean Carey10, Sarah E. Ragan11 and Thomas Henning11 1 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei M¨unchen, Germany 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA 3 Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands 4 Department of Astronomy, School of Physics, Peking University, Beijing 100871, China 5 Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching bei M¨unchen, Germany 6 INAF – Osservatorio astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy 7 SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands

50 8 California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA 9 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ogel 69, D-53121 Bonn, Germany 10 Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125, USA 11 Max-Planck Institute f¨ur Astronomie, K¨onigstuhl 17, D-69117 Heidelberg, Germany E-mail contact: kwang at eso.org We present Submillimeter Array (SMA) λ = 0.88 and 1.3 mm broad band observations, and the Jansky Very Large Array (VLA) observations in NH3 (J, K)=(1, 1) up to (5, 5), H2O and CH3OH maser lines toward the two most mas- sive molecular clumps in (IRDC) G11.11-0.12. Sensitive high-resolution images reveal hierarchical fragmentation in dense molecular gas from the ∼ 1 pc clump scale down to ∼ 0.01 pc condensation scale. At each scale, the mass of the fragments is orders of magnitude larger than the Jeans mass. This is common to all four IRDC clumps we studied, suggesting that turbulence plays an important role in the early stages of clustered star formation. Masers, shock heated NH3 gas, and outflows indicate intense ongoing star formation in some cores while no such signatures are found in others. Furthermore, chemical differentiation may reflect the difference in evolutionary stages among these star formation seeds. We find NH3 ortho/para ratios of 1.1 ± 0.4, 2.0 ± 0.4, and 3.0 ± 0.7 associated with three outflows, and the ratio tends to increase along the outflows downstream. Our combined SMA and VLA observations of several IRDC clumps present the most in depth view so far of the early stages prior to the hot core phase, revealing snapshots of physical and chemical properties at various stages along an apparent evolutionary sequence. Accepted by MNRAS http://arxiv.org/pdf/1401.4157

Unbound Star-forming Molecular Clouds Rachel L. Ward1, James Wadsley1, and Alison Sills1 1 Department of Physics and Astronomy, McMaster University, Hamilton, ON, L8S 4M1, Canada E-mail contact: rlward at mcmaster.ca We explore whether observed molecular clouds could include a substantial population of unbound clouds. Using simulations which include only turbulence and gravity, we are able to match observed relations and naturally reproduce the observed scatter in the cloud size-linewidth coefficient, at fixed surface density. We identify the source of this scatter as a spread in the intrinsic virial parameter. Thus these observational trends do not require that clouds exist in a state of dynamical equilibrium. We demonstrate that cloud virial parameters can be accurately determined observationally with an appropriate size estimator. All our simulated clouds eventually form collapsing cores, regardless of whether the cloud is bound overall. This supports the idea that molecular clouds do not have to be bound to form stars or to have observed properties like those of nearby low-mass clouds. Accepted by MNRAS http://arxiv.org/pdf/1401.1464

Stochastic accretion of planetesimals onto white dwarfs: constraints on the mass distri- bution of accreted material from atmospheric pollution M. C. Wyatt1, J. Farihi1, J. E. Pringle1 and A. Bonsor2,3 1 Institute of Astronomy, Madlingley Road, Cambridge CB3 0HA, UK 2 Institut de Plan´etologie et d’Astrophysique de Grenoble, Universit´eJoseph Fourier, CNRS, BP 53, 38041 Grenoble, France 3 H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK E-mail contact: wyatt at ast.cam.ac.uk This paper explores how the stochastic accretion of planetesimals onto white dwarfs would be manifested in observations of their atmospheric pollution. Archival observations of pollution levels for unbiased samples of DA and non-DA white dwarfs are used to derive the distribution of inferred accretion rates, confirming that rates become systematically lower as sinking time (assumed here to be dominated by gravitational settling) is decreased, with no discernable dependence on cooling age. The accretion rates expected from planetesimals that are all the same mass (i.e., a mono-

51 mass distribution) are explored both analytically and using a Monte Carlo model, quantifying how measured accretion rates inevitably depend on sinking time, since different sinking times probe different times since the last accretion event. However, that dependence is so dramatic that a mono-mass distribution can be excluded within the context of this model. Consideration of accretion from a broad distribution of planetesimal masses uncovers an important conceptual difference: accretion is continuous (rather than stochastic) for planetesimals below a certain mass, and the accretion of such planetesimals determines the rate typically inferred from observations; smaller planetesimals dominate the rates for shorter sinking times. A reasonable fit to the observationally inferred accretion rate distributions is found with model parameters consistent with a collisionally evolved mass distribution up to Pluto-mass, and an underlying accretion rate distribution consistent with that expected from descendants of debris discs of main sequence A stars. With these parameters, while both DA and non-DA white dwarfs accrete from the same broad planetesimal distribution, this model predicts that the pollution seen in DAs is dominated by the continuous accretion of < 35 km objects, and that in non-DAs by > 35 km objects (though the dominant size varies between stars by around an order of magnitude from this reference value). Further observations that characterise the dependence of inferred accretion rates on sinking time and cooling age (including a consideration of the effect of thermohaline convection on models used to derive those rates), and the decadal variability of DA accretion signatures, will improve constraints on the mass distribution of accreted material and the lifetime of the disc through which it is accreted. Accepted by MNRAS http://arxiv.org/pdf/1401.6173

Comparing Simulated Emission from Molecular Clouds Using Experimental Design Miayan Yeremi1, Mallory Flynn1, Stella Offner2,3, Jason Loeppky1, and Erik Rosolowsky1,4 1 University of British Columbia, Okanagan Campus, Departments of Physics and Statistics, 3333 University Way, Kelowna BC V1V 1V7 Canada 2 Yale University Astronomy Department, 260 Whitney Ave, New Haven, CT 06511, USA 3 Hubble Fellow 4 University of Alberta, Department of Physics, 4-181 CCIS, Edmonton AB T6G 2E1, Canada E-mail contact: erosolow at ualberta.ca We propose a new approach to comparing simulated observations that enables us to determine the significance of the underlying physical effects. We utilize the methodology of experimental design, a subfield of statistical analysis, to establish a framework for comparing simulated position-position-velocity data cubes to each other. We propose three similarity metrics based on methods described in the literature: principal component analysis, the spectral correlation function, and the Cramer multi-variate two sample similarity statistic. Using these metrics, we intercompare a suite of mock observational data of molecular clouds generated from magnetohydrodynamic simulations with varying physical conditions. Using this framework, we show that all three metrics are sensitive to changing Mach number and temperature in the simulation sets, but cannot detect changes in magnetic field strength and initial velocity spectrum. We highlight the shortcomings of one-factor-at-a-time designs commonly used in astrophysics and propose fractional factorial designs as a means to rigorously examine the effects of changing physical properties while minimizing the investment of computational resources. Accepted by ApJ http://arxiv.org/pdf/1401.6251

Accretion onto Planetary Mass Companions of Low-Mass Young Stars Yifan Zhou1,2, Gregory J. Herczeg1,2, Adam L. Kraus3, Stanimir Metchev4,5 and Kelle L. Cruz6,7 1 Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, Beijing 100871, Peoples Republic of China 2 Department of Astronomy, School of Physics, Peking University, Yi He Yuan Lu 5, Haidian District, Beijing 100871, P.R. China 3 Department of Astronomy, The University of Texas at Austin, Austin, TX 78712, USA 4 Department of Physics & Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada

52 5 Department of Physics and Astronomy, State University of New York, Stony Brook, NY 11794, USA 6 Hunter College, City University of New York, Dept. of Physics and Astronomy, New York, NY 10065 7 American Museum of Natural History, Astrophysics Dept, New York, NY 10025 E-mail contact: Zhouyifan1012 at pku.edu.cn Measurements of accretion rates onto planetary mass objects may distinguish between different planet formation mechanisms, which predict different accretion histories. In this Letter, we use HST/WFC3 UVIS optical photometry to measure accretion rates onto three accreting objects, GSC06214-00210 b, GQ Lup b, and DH Tau b, that are at the planet/brown dwarf boundary and are companions to solar mass stars. The excess optical emission in the excess −9 −11 −1 accretion continuum yields mass accretion rates of 10 to 10 M⊙ yr for these three objects. Their accretion rates are an order of magnitude higher than expected from the correlation between mass and accretion rates measured from the UV excess, which is applicable if these wide planetary mass companions formed by protostellar core fragmentation. The high accretion rates and large separation from the central star demonstrate the presence of massive disks around these objects. Models for the formation and evolution of wide planetary mass companions should account for their large accretion rates. High ratios of Hα luminosity over accretion luminosity for objects with low accretion rates suggest that searches for Hα emission may be an efficient way to find accreting planets. Accepted by ApJL http://arxiv.org/pdf/1401.6545

53 Abstracts of recently accepted major reviews

Episodic Accretion in Young Stars Marc Audard1, P´eter Abrah´am´ 2, Michael M. Dunham3, Joel D. Green4, Nicolas Grosso5, Kenji Hamaguchi6,7, Joel H. Kastner8, Agnes´ K´osp´al9, Giuseppe Lodato10, Marina M. Romanova11, Stephen L. Skinner12, Eduard I. Vorobyov13,14 and Zhaohuan Zhu15 1 University of Geneva 2 Konkoly Observatory 3 Yale University 4 University of Texas at Austin 5 Observatoire Astronomique de Strasbourg 6 National Aeronautics and Space Administration 7 University of Maryland, Baltimore County 8 Rochester Institute of Technology 9 European Space Agency 10 Universit`aDegli Studi di Milano 11 Cornell University 12 University of Colorado at Boulder 13 University of Vienna 14 Southern Federal University 15 Princeton University E-mail contact: Marc.Audard at unige.ch In the last twenty years, the topic of episodic accretion has gained significant interest in the star formation community. It is now viewed as a common, though still poorly understood, phenomenon in low-mass star formation. The FU Orionis objects (FUors) are long-studied examples of this phenomenon. FUors are believed to undergo accretion outbursts −7 −4 −1 during which the accretion rate rapidly increases from typically 10 to a few 10 M⊙ yr , and remains elevated over several decades or more. EXors, a loosely defined class of pre-main sequence stars, exhibit shorter and repetitive outbursts, associated with lower accretion rates. The relationship between the two classes, and their connection to the standard pre-main sequence evolutionary sequence, is an open question: do they represent two distinct classes, are they triggered by the same physical mechanism, and do they occur in the same evolutionary phases? Over the past couple of decades, many theoretical and numerical models have been developed to explain the origin of FUor and EXor outbursts. In parallel, such accretion bursts have been detected at an increasing rate, and as observing techniques improve each individual outburst is studied in increasing detail. We summarize key observations of pre-main sequence star outbursts, and review the latest thinking on outburst triggering mechanisms, the propagation of outbursts from star/disk to disk/jet systems, the relation between classical EXors and FUors, and newly discovered outbursting sources – all of which shed new light on episodic accretion. We finally highlight some of the most promising directions for this field in the near- and long-term. Accepted by Accepted by Protostars and Planets VI http://arxiv.org/pdf/1401.3368v1

Planetary internal structures Isabelle Baraffe1, Gilles Chabrier2,3, Jonathan Fortney4, and Christophe Sotin5 1 University of Exeter, Physics and Astronomy, Exeter, United Kingdom 2 Ecole Normale Sup´erieure de Lyon, CRAL, France 3 University of Exeter, Physics and Astronomy, Exeter, United Kingdom 4 University of California, Astronomy and Astrophysics, Santa Cruz, United States of America

54 5 JPL, Caltech, Pasadena, United States of America E-mail contact: i.baraffe at ex.ac.uk This chapter reviews the most recent advancements on the topic of terrestrial and giant planet interiors, including Solar System and extrasolar objects. Starting from an observed mass-radius diagram for known planets in the Universe, we will discuss the various types of planets appearing in this diagram and describe internal structures for each type. The review will summarize the status of theoretical and experimental works performed in the field of equation of states (EOS) for materials relevant to planetary interiors and will address the main theoretical and experimental uncertainties and challenges. It will discuss the impact of new EOS on interior structures and bulk composition determination. We will discuss important dynamical processes which strongly impact the interior and evolutionary properties of planets (e.g plate tectonics, semiconvection) and describe non standard models recently suggested for our giant planets. We will address the case of short-period, strongly irradiated exoplanets and critically analyse some of the physical mechanisms which have been suggested to explain their anomalously large radius. Accepted by PPVI http://arxiv.org/pdf/1401.4738

Giant planet and brown dwarf formation G. Chabrier1, A. Johansen2, M. Janson3,4 and R. Rafikov4 . 1 ENS-Lyon, France 2 Lund Unversity, Sweden 3 Queen’s University Belfast, UK 4 Princeton University, USA E-mail contact: chabrier at ens-lyon.fr Understanding the dominant brown dwarf and giant planet formation processes, and finding out whether these pro- cesses rely on completely different mechanisms or share common channels represents one of the major challenges of astronomy and remains the subject of heated debates. It is the aim of this review to summarize the latest developments in this field and to address the issue of origin by confronting different brown dwarf and giant planet formation scenarios to presently available observational constraints. As examined in the review, if objects are classified as ”Brown Dwarfs” or ”Giant Planets” on the basis of their formation mechanism, it has now become clear that their mass domains overlap and that there is no mass limit between these two distinct populations. Furthermore, while there is increasing observational evidence for the existence of non-deuterium burning brown dwarfs, some giant planets, characterized by a significantly metal enriched composition, might be massive enough to ignite deuterium burning in their core. Deuterium burning (or lack of) thus plays no role in either brown dwarf or giant planet formation. Consequently, we argue that the IAU definition to distinguish these two populations has no physical justification and brings scientific confusion. In contrast, brown dwarfs and giant planets might bear some imprints of their formation mechanism, notably in their mean density and in the physical properties of their atmosphere. Future direct imaging surveys will undoubtedly provide crucial information and perhaps provide some clear observational diagnostics to unambiguously distinguish these different astrophysical objects. Accepted for publication as a chapter in Protostars and Planets VI, University of Arizona Press (2014) http://arxiv.org/pdf/1401.7559

The Evolution of Protostars: Insights from Ten Years of Infrared Surveys with Spitzer and Herschel Michael M. Dunham1,2, Amelia M. Stutz3, Lori E. Allen4, Neal J. Evans II5, William J. Fischer6, S. Thomas Megeath6, Philip C. Myers2, Stella S. R. Offner7, Charles A. Poteet8, John J. Tobin9 and Eduard I. Vorobyov10,11 1 Yale University 2 Harvard-Smithsonian Center for Astrophysics 3 Max Planck Institute for Astronomy 4 National Optical Astronomy Observatory

55 5 The University of Texas at Austin 6 The University of Toledo 7 Yale University 8 Rensselaer Polytechnic Institute 9 National Radio Astronomy Observatory 10 University of Vienna 11 Southern Federal University E-mail contact: mdunham at cfa.harvard.edu Stars form from the gravitational collapse of dense molecular cloud cores. In the protostellar phase, mass accretes from the core onto a protostar, likely through an accretion disk, and it is during this phase that the initial masses of stars and the initial conditions for planet formation are set. Over the past decade, new observational capabilities provided by the Spitzer Space Telescope and Herschel Space Observatory have enabled wide-field surveys of entire star-forming clouds with unprecedented sensitivity, resolution, and infrared wavelength coverage. We review resulting advances in the field, focusing both on the observations themselves and the constraints they place on theoretical models of star formation and protostellar evolution. We also emphasize open questions and outline new directions needed to further advance the field. Accepted by Protostars and Planets VI http://arxiv.org/pdf/1401.1809

The Earliest Stages of Star and Planet Formation: Core Collapse, and the Formation of Disks and Outflows Zhi-Yun Li1, Robi Banerjee2, Ralph E. Pudritz3, Jes K. Jørgensen4, Hsien Shang5, Ruben Krasnopolsky5 and Ana¨elle Maury6 1 University of Virginia 2 Universit¨at Hamburg 3 McMaster University 4 Copenhagen University 5 Academia Sinica 6 Harvard-Smithsonian Center for Astrophysics E-mail contact: zl4h at virginia.edu The formation of stars and planets are connected through disks. Our theoretical understanding of disk formation has undergone drastic changes in recent years, and we are on the brink of a revolution in disk observation enabled by ALMA. Large rotationally supported circumstellar disks, although common around more evolved young stellar objects, are rarely detected during the earliest, “Class 0” phase; a few excellent candidates have been discovered recently around both low- and high-mass protostars though. In this early phase, prominent outflows are ubiquitously observed; they are expected to be associated with at least small magnetized disks. Whether the paucity of large Keplerian disks is due to observational challenges or intrinsically different properties of the youngest disks is unclear. In this review we focus on the observations and theory of the formation of early disks and outflows, and their connections with the first phases of planet formation. Disk formation — once thought to be a simple consequence of the conservation of angular momentum during hydrodynamic core collapse — is far more subtle in magnetized gas. In this case, the rotation can be strongly magnetically braked. Indeed, both analytic arguments and numerical simulations have shown that disk formation is suppressed in the strict ideal magnetohydrodynamic (MHD) limit for the observed level of core magnetization. We review what is known about this “magnetic braking catastrophe”, possible ways to resolve it, and the current status of early disk observations. Possible resolutions include non-ideal MHD effects (ambipolar diffusion, Ohmic dissipation and Hall effect), magnetic interchange instability in the inner part of protostellar accretion flow, turbulence, misalignment between the magnetic field and rotation axis, and depletion of the slowly rotating envelope by outflow stripping or accretion. Outflows are also intimately linked to disk formation; they are a natural product of magnetic fields and rotation and are important signposts of star formation. We review new developments on early outflow generation since PPV. The properties of early disks and outflows are a key component of planet formation in its early stages and we review these major connections.

56 Accepted by Protostars and Planets VI http://arxiv.org/pdf/1401.2219.pdf

Observations, Modeling and Theory of Debris Disks Brenda C. Matthews1, Alexander V. Krivov2, Mark C. Wyatt3, Geoffrey Bryden4 and Carlos Eiroa5 1 National Research Council of Canada - Herzberg Astronomy & Astrophysics Programs 2 Friedrich-Schiller-Universit¨at Jena 3 University of Cambridge 4 Jet Propulsion Laboratory 5 Universidad Aut´onoma de Madrid E-mail contact: brenda.matthews at nrc-cnrc.gc.ca Main sequence stars, like the Sun, are often found to be orbited by circumstellar material that can be categorized into two groups, planets and debris. The latter is made up of asteroids and comets, as well as the dust and gas derived from them, which makes debris disks observable in thermal emission or scattered light. These disks may persist over Gyrs through steady-state evolution and/or may also experience sporadic stirring and major collisional breakups, rendering them atypically bright for brief periods of time. Most interestingly, they provide direct evidence that the physical processes (whatever they may be) that act to build large oligarchs from micron-sized dust grains in protoplanetary disks have been successful in a given system, at least to the extent of building up a significant planetesimal population comparable to that seen in the Solar System s asteroid and Kuiper belts. Such systems are prime candidates to host even larger planetary bodies as well. The recent growth in interest in debris disks has been driven by observational work that has provided statistics, resolved images, detection of gas in debris disks, and discoveries of new classes of objects. The interpretation of this vast and expanding dataset has necessitated significant advances in debris disk theory, notably in the physics of dust produced in collisional cascades and in the interaction of debris with planets. Application of this theory has led to the realization that such observations provide a powerful diagnostic that can be used not only to refine our understanding of debris disk physics, but also to challenge our understanding of how planetary systems form and evolve. Accepted by Protostars & Planets VI http://arxiv.org/pdf/1401.0743

Volatiles in protoplanetary disks Klaus M. Pontoppidan1, Colette Salyk2, Edwin A. Bergin3, Sean Brittain4, Bernard Marty5, Olivier Mousis6, Karin I. Oberg¨ 7 1 Space Telescope Science Institute 2 National Optical Astronomy Observatory 3 University of Michigan 4 Clemson University 5 Universit´ede Lorraine 6 Universit´ede Franche-Comt´e 7 Harvard University E-mail contact: pontoppi at stsci.edu Volatiles are compounds with low sublimation temperatures, and they make up most of the condensible mass in typical planet-forming environments. They consist of relatively small, often hydrogenated, molecules based on the abundant elements carbon, nitrogen and oxygen. Volatiles are central to the process of planet formation, forming the backbone of a rich chemistry that sets the initial conditions for the formation of planetary atmospheres, and act as a solid mass reservoir catalyzing the formation of planets and planetesimals. This growth has been driven by rapid advances in observations and models of protoplanetary disks, and by a deepening understanding of the cosmochemistry of the solar system. Indeed, it is only in the past few years that representative samples of molecules have been discovered in great abundance throughout protoplanetary disks - enough to begin building a complete budget for the most abundant elements after hydrogen and helium. The spatial distributions of key volatiles are being

57 mapped, snow lines are directly seen and quantified, and distinct chemical regions within protoplanetary disks are being identified, characterized and modeled. Theoretical processes invoked to explain the solar system record are now being observationally constrained in protoplanetary disks, including transport of icy bodies and concentration of bulk condensibles. The balance between chemical reset - processing of inner disk material strong enough to destroy its memory of past chemistry, and inheritance - the chemically gentle accretion of pristine material from the interstellar medium in the outer disk, ultimately determines the final composition of pre-planetary matter. This chapter focuses on making the first steps toward understanding whether the planet formation processes that led to our solar system are universal. Accepted by PPVI http://arxiv.org/pdf/1401.2423

Ages of Young Stars David R. Soderblom1, Lynne A. Hillenbrand2, Rob. D. Jeffries3, Eric E. Mamajek4 and Tim Naylor5 1 Space Telescope Science Institute 2 Department of Astronomy, California Institute of Technology 3 Astrophysics Group, Keele University 4 Department of Physics and Astronomy, University of Rochester 5 School of Physics, University of Exeter E-mail contact: drs at stsci.edu Determining the sequence of events in the formation of stars and planetary systems and their time-scales is essential for understanding those processes, yet establishing ages is fundamentally difficult because we lack direct indicators. In this review we discuss the age challenge for young stars, specifically those less than ∼100 Myr old. Most age determination methods that we discuss are primarily applicable to groups of stars but can be used to estimate the age of individual objects. A reliable age scale is established above 20 Myr from measurement of the Lithium Depletion Boundary (LDB) in young clusters, and consistency is shown between these ages and those from the upper main sequence and the main sequence turn-off – if modest core convection and rotation is included in the models of higher- mass stars. Other available methods for age estimation include the kinematics of young groups, placing stars in Hertzsprung-Russell diagrams, pulsations and seismology, measurement, rotation and activity, and lithium abundance. We review each of these methods and present known strengths and weaknesses. Below ∼ 20 Myr, both model-dependent and observational uncertainties grow, the situation is confused by the possibility of age spreads, and no reliable absolute ages yet exist. The lack of absolute age calibration below 20 Myr should be borne in mind when considering the lifetimes of protostellar phases and circumstellar material. Accepted by Protostars & Planets VI http://arxiv.org/pdf/1311.7024

Massive Star Formation Jonathan C. Tan1, Maria T. Beltr´an2, Paola Caselli3, Francesco Fontani2, Asunci´on Fuente4, Mark R. Krumholz5, Christopher F. McKee6, Andrea Stolte7 1 University of Florida 2 INAF-Osservatorio Astrofisico di Arcetri 3 University of Leeds 4 Observatorio Astron´omico Nacional 5 University of California, Santa Cruz 6 University of California, Berkeley 7 Argelander Institut f¨ur Astronomie, Universit¨at Bonn E-mail contact: jt at astro.ufl.edu The enormous radiative and mechanical luminosities of massive stars impact a vast range of scales and processes, from the reionization of the universe, to the evolution of galaxies, to the regulation of the interstellar medium, to the formation of star clusters, and even to the formation of planets around stars in such clusters. Two main classes of

58 massive star formation theory are under active study, Core Accretion and Competitive Accretion. In Core Accretion, the initial conditions are self-gravitating, centrally concentrated cores that condense with a range of masses from the surrounding, fragmenting clump environment. They then undergo relatively ordered collapse via a central disk to form a single star or a small-N multiple. In this case, the pre- mass function has a similar form to the stellar initial mass function. In Competitive Accretion, the material that forms a massive star is drawn more chaotically from a wider region of the clump without passing through a phase of being in a massive, coherent core. In this case, massive star formation must proceed hand in hand with formation. If stellar densities become very high near the cluster center, then collisions between stars may also help to form the most massive stars. We review recent theoretical and observational progress towards understanding massive star formation, considering physical and chemical processes, comparisons with low and intermediate-mass stars, and connections to star cluster formation. Accepted for publication as a chapter in Protostars and Planets VI, University of Arizona Press (2014), eds. H. Beuther, R. Klessen, C. Dullemond, Th. Henning http://arxiv.org/pdf/1402.0919

Transport and Accretion in Planet-Forming Disks N. J. Turner1, S. Fromang2, C. Gammie3, H. Klahr4, G. Lesur5, M. Wardle6 and X.-N. Bai7 1 Jet Propulsion Laboratory, California Institute of Technology 2 Service d’Astrophysique de Saclay 3 University of Illinois at Urbana-Champaign 4 Max Planck Institute for Astronomy 5 Institute for Planetology and Astrophysics of Grenoble 6 Macquarie University 7 Harvard-Smithsonian Center for Astrophysics E-mail contact: neal.turner at jpl.nasa.gov Planets appear to form in environments shaped by the gas flowing through protostellar disks to the central young stars. The flows in turn are governed by orbital angular momentum transfer. In this chapter we summarize current understanding of the transfer processes best able to account for the flows, including magneto-rotational turbulence, magnetically-launched winds, self-gravitational instability and vortices driven by hydrodynamical instabilities. For each in turn we outline the major achievements of the past few years and the outstanding questions. We underscore the requirements for operation, especially ionization for the magnetic processes and heating and cooling for the others. We describe the distribution and strength of the resulting flows and compare with the long-used phenomenological α-picture, highlighting issues where the fuller physical picture yields substantially different answers. We also discuss the links between magnetized turbulence and magnetically-launched outflows, and between magnetized turbulence and hydrodynamical vortices. We end with a summary of the status of efforts to detect specific signatures of the flows. Accepted by Protostars & Planets VI, Univ. of Arizona Press, eds. H. Beuther, R. Klessen, C. Dullemond & Th. Henning http://arxiv.org/pdf/1401.7306 The conference talk is at http://youtube.com/watch?v=tEgw0PXwkGE

59 Dissertation Abstracts

Statistical studies of planet frequency: Understanding planet formation

Annelies Mortier

Centro de Astrof´ısica da Universidade do Porto, Portugal Rua das Estrelas, 4150-762 Porto, Portugal Electronic mail: amortier at astro.up.pt Ph.D dissertation directed by: Nuno C. Santos Ph.D degree awarded: December 2013

In this thesis I present the results of the work done during my PhD. It revolves mainly around the frequency of giant planets as a function of various stellar parameters, like the stellar metallicity and mass. Understanding these correlations and their significance helps in narrowing down the theories of planet formation and evolution. FGK dwarfs that host giant planets are found to be more metal-rich than stars that are not orbited by a giant planet. Dedicated planet searches are thus performed with metal-poor stars to understand how rare exactly giant planets are around these stars. In Chapter 2, I report on the results of a study of two such metal-poor samples that were searched for planets. By studying the detection limits in the data, I quantified the frequency of giant planets, and in particular hot Jupiters, around these metal-poor stars. I found that giant planets are indeed rare around metal-poor stars, but that their frequency may be higher than what is expected from a purely exponential relation with metallicity. Chapter 3 reports on the results of a Bayesian study of a large volume-limited planet-search sample of FGK dwarfs. Different functional forms are tested to describe the giant planet frequency around FGK dwarfs. For metal-poor stars both a constant as an exponential dependence is investigated. The possible dependence of mass is also explored. Comparing these models with a Bayesian analysis revealed that none of them was statistically significant or could be ruled out. Chapter 4 describes the giant planet frequency around evolved stars. An appropriate line list is tested for deriving stellar parameters of evolved stars. With these precise stellar parameters, the giant planet frequency around evolved stars is explored. For giant stars (with log g < 3.0), it appears that there is no dependency on metallicity. still show an increasing trend. The last part of this thesis is about precise and accurate stellar parameters for transit hosts. For transiting planets, the stellar density can be directly derived using the transit light curve. This density will provide an independent measurement of the surface gravity which is not well constrained using spectroscopy. I show that this difference in surface gravity mostly has an effect on the derivation of the stellar, and thus planetary, radius. http://astro.up.pt/~amortier/Thesis_final.pdf

60 New Jobs

Post-doctoral position in star formation, U. de Chile Santiago

The UMI-FCA and department of astronomy of the Universidad de Chili invites applications for a 2 year research fellowship on star and planet formation. The UMI-FCA is a french-chilean collaboration hosted at the department of astronomy of the Universidad de Chili (see http://www.das.uchile.cl/das_proyectos.html). The selected post-doctoral candidate will work with Dr Catherine Dougados on multi-wavelength spectro-imaging studies of protostellar jets/outflows. This project is aimed at providing stringent observational tests to jet launching models in a large variety of sources and will exploit the synergy between ALMA and VLT optical/near-IR spectro- imagers (SINFONI, MUSE, SPHERE). Collaborations are foreseen with D. Mardones & G. Garay (DAS) specialists of embedded young stellar objects and massive protostars and S. Cabrit (Obs Paris, France) for the comparison to model predictions. The applicant should have a PhD in astronomy/astrophysics. We seek candidates with interest in star formation and more specifically protostellar outflows/jets. Ideally, candidates should also have expertise in radio interferometry and/or optical/near-infrared spectroscopy. However broader profiles will be considered. The applicant will be also encouraged to develop his own research lines in the context of star and planetary formation. The selected candidate will benefit from the privileged collaborations with the european and french astronomical communities via the UMI- FCA and from the strong scientific expertise in ALMA observations, protostellar objects and proto-planetary disc physics (see http://mad.das.uchile.cl) present at DAS. This position is funded through an ESO-governement of Chili grant. The position is available as soon as possible with a starting date ideally no later than June 2014. Fellows will receive a competitive salary as well as a research budget. While holding the position the fellow will be eligible for the 10% host country observing time on all telescopes in Chile, including ALMA. He/she will also have access to all french facilities via the UMI-FCA. Interested researchers should send a CV (including publication list) and description of research interests (max of 3 pages) to Dr. Catherine Dougados ([email protected]). Applicants should also request for at least 2 letters of recommendation to be sent directly from the writers. Closing date for receipt of applications is 21st March 2014. Late applications may be considered until the position is filled.

Postdoctoral Position for High-Angular Resolution Studies of Protoplanetary Disks

The astrophysics group at the University of Exeter invites applications for a postdoctoral position (Associate Research Fellow / Research Fellow) to work primarily with Dr. Stefan Kraus on observational studies related to star and planet formation. This position is funded through grants from the EU Marie Curie actions and the Leverhulme Trust. The post is funded for a fixed term period of 3 years and is expected to commence around October 2014, with a 12 month probationary period. The broad goal of the position is to carry out original research on protoplanetary disks using high-angular resolution observations. The successful applicant will work in collaboration with the PI on modelling VLTI infrared and/or ALMA sub-millimeter interferometric data and complementary spectroscopic data. We are particularly interested in applicants with experience in modelling the line/continuum emission of protoplanetary disks or a strong background in accretion/outflow-launching physics. Prior experience with the technique of interferometry is not required, but would be an asset.

61 Applicants must possess a PhD in astrophysics or a related discipline, or expect to have earned one before taking up the position. The salary will range from £25,014 to £32,590 per annum, depending on qualifications and experience. Supercomputing resources and funding for computing equipment and travel will be available, and we will provide assistance with relocation costs where eligible. For further information or to apply, please contact Dr. Stefan Kraus (email: [email protected]). An application should consist of a completed application and equal opportunities form along with a CV, covering letter and the details of three referees. The corresponding forms can be found at http://jobs.exeter.ac.uk (search for keyword P46264). The deadline is February 28, 2014, but later applications may also be considered until the position is filled.

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62 Meetings

Second announcement The 2014 STScI Spring Symposium Habitable Worlds Across Time and Space Space Telescope Science Institute, Baltimore MD (USA) April 28-May 1, 2014

http://www.stsci.edu/institute/conference/habitable-worlds Abstract submission deadline: February 28, 2014 On-line registration deadline: March 28, 2014 (Registration now open!) Registration Fee: $75

Within a matter of years, humanity will know for the first time the frequency of terrestrial planets in orbit around other stars. This knowledge will pave the way for joining research from astronomy, Earth science, and biology to understand the past, present, and future of the Earth within its larger context as one of many habitable worlds throughout the Galaxy. Such work seeks to understand the formation and fate of the Earth as well as predict where and when different bodies will be suitable for both simple and complex forms of life. In this four-day symposium, scientists from diverse fields will discuss the formation and long-term evolution of ter- restrial bodies throughout the various phases of stellar and Galactic evolution. A particular focus will be in how the specific conditions and challenges for habitability on Earth extend to other bodies in the Solar System and beyond. This symposium will include discussions about sites for Galactic habitability that have not yet been given much atten- tion, such as around post-main sequence stars. The existence of these overlooked environments may provide motivation for novel astronomical observations with existing and next generation ground and space-based observatories. Invited speakers will cover the following topics:

• Terrestrial planet formation, volatile delivery, and the formation of • Early Earth geochemistry, atmosphere, and the origins of life • The frequency of terrestrial planets across • The limits to Earth-like life • Habitability of planets and moons during all phases of stellar evolution • Habitability in low-luminosity environments

Registration for this Symposium is now open and attendance is limited. Please visit: http://www.stsci.edu/institute/conference/habitable-worlds and click on the ’Register’ link. We also invite contributions in the form of talks and posters, which can be submitted during the registration process or after one has registered. Only a small number of contributed talks will be selected, others will be presented as posters.

63 Star Formation Across Space and Time 11-14 November 2014 ESA/ESTEC, Noordwijk, The Netherlands

The objective of this meeting is to bring together astronomers interested in all aspects of star formation, from local galactic to extreme extra-galactic high-z conditions. Recent advances on the subject suggest various communities can benefit from each other, and the meeting aims to facilitate cross-fertilization between researchers with different observational and theoretical backgrounds to further our understanding of star formation as observed across the spectrum. The meeting poses the fundamental question: Are there universal processes of star formation across space and time? Topics are meant to be wide in scope, and can include but need not be limited to:

• What fraction of low and high mass star formation takes place in filaments, shells, pillars and other commonly observed structures? What are the processes of star formation in these structures? Are stars forming inside and outside of such structures the same? • How do the properties of star-forming clouds change with cosmic time and with galaxy type and metallicity in the local universe? Is there a universality to cloud formation, structure, internal dynamics and disruption? To what extent can local clouds be used as templates for understanding high-z star formation? • What causes the galaxy main sequence and deviations from it? What causes star formation quenching and how does it vary with galaxy mass and environment? • How important is feedback to the star formation process and star formation rate over cloud scales and galaxy scales?

• Can the origin and history of galaxies inferred from the evolutionary changes seen in the galaxy population be reconciled with our understanding of the physics of star formation?

Scientific Organising Committee: Philippe Andr´e, CEA, Saclay, France Steve Eales, Cardiff University, UK David Elbaz, CEA, Saclay, France Bruce Elmegreen, IBM, USA Neal Evans, University of Texas, USA Yasuo Fukui, University of Nagoya, Japan Eve Ostriker, Princeton University, USA G¨oran Pilbratt, ESA, Noordwijk, Netherlands Nick Scoville, Caltech, Pasadena, USA Linda Tacconi, MPE, Garching, Germany

The First Announcement has been issued on 24 January 2014. The Second Announcement and Call for Papers will be issued in May 2014 with a deadline for abstract submission in August 2014. All information about the meeting is available on the conference website below. Website: http://congrexprojects.com/14a09/ Contact: [email protected]

64 Cloudy summer school 2014

Nearly all of the quantitative information we have about the cosmos is the result of the analysis of spectra. We can directly measure the temperature, density, pressure, or composition of a cloud of gas or a star, using a telescope and a spectrometer. This spectrum forms in highly non-equilibrium gas and dust. Analytical theory cannot be used to understand the conditions in such a region. Cloudy is a code that simulates such environments. It calculates the plasma, chemistry, radiation transport, and dy- namics problems simultaneously and self consistently, building from the foundation of individual atomic and molecular processes. The result is a prediction of the conditions in the material and its observed spectrum. Goal of this course The School will cover observation, theory, and application of Cloudy to a wide variety of astronomical environments. This includes the theory of diffuse non-LTE matter and quantitative spectroscopy (the science of using spectra to make physical measurements. We will use Cloudy to simulate such objects as AGB stars, Active Galactic Nuclei, Starburst galaxies, and the intergalactic medium. The sessions will consist of a mix of textbook study, using Osterbrock & Ferland, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei, application of the spectral-simulation code Cloudy to a variety of astrophysical problems, and projects organized by the participants. No prior experience with Cloudy is assumed. More information: http://cloud9.pa.uky.edu/~gary/cloudy/CloudySummerSchool/

Bringing Fundamental Astrophysical Processes Into Focus: A Community Workshop to Plan the Future of Far-Infrared Space Astrophysics

This will be the next workshop in a series of such meetings held over the past 15 years. A 2002 workshop culminated in the development of a US “Community Plan for Far-IR Space Astrophysics”, which gave the workshop participants’ consensus recommendations and served as the foundation for later versions of the Plan. The most recent version of the Community Plan was submitted to the Decadal Survey Committee in 2009. The objective of the May 2014 workshop is to re-convene the community, align with a changed scientific, technical, and programmatic landscape, and renew consensus. The NASA Astrophysics Roadmap, “Enduring Quests, Daring Visions: NASA Astrophysics in the Next Three Decades” provides a new framework for discussion. For information, contact David Leisawitz ([email protected]) http://asd.gsfc.nasa.gov/conferences/FIR/index.html

65 Summary of Upcoming Meetings

Herbig Ae/Be stars: The missing link in star formation 7 - 11 April 2014 Santiago, Chile http://www.eso.org/haebe2014.html The Interaction of Stars with the Interstellar Medium of Galaxies 20 - 25 April 2014 Les Houches, France http://ism2014.strw.leidenuniv.nl Habitable Worlds Across Time and Space 28 April - 1 May 2014 Baltimore, USA http://www.stsci.edu/institute/conference/habitable-worlds The Formation of the Solar System 13 - 15 May 2014 MPIfR, Bonn, Germany https://indico.mpifr-bonn.mpg.de/theFormationOfTheSolarSystem The Olympian Symposium on Star Formation 26 - 30 May 2014 Paralia Katerini’s, Mount Olympus, Greece http://zuserver2.star.ucl.ac.uk/~ossf14/ EPoS2014 The Early Phase of Star Formation 1 - 6 June 2014 Ringberg Castle, Tegernsee, Germany http://www.mpia-hd.mpg.de/homes/stein/EPoS/epos.php The Dance of Stars: Dense Stellar Systems from Infant to Old 2 - 6 June 2014 Bad Honnef, Germany http://www.astro.uni-bonn.de/$\sim$sambaran/DS2014/index.html The 18th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun 9 - 13 June 2014 Flagstaff, Arizona, USA http://www2.lowell.edu/workshops/coolstars18/ Summer School on Protoplanetary Disks: Theory and Modeling meet Observations 16 - 20 June 2014 Groningen, The Netherlands http://www.diana-project.com/summer-school Characterizing Planetary Systems Across the HR Diagram 28 July - 1 August 2014 Inst. for Astronomy, Cambridge, USA http://www.ast.cam.ac.uk/meetings/2013/AcrossHR Planet Formation and Evolution 2014 8 - 10 September 2014 Kiel, Germany http://www.astrophysik.uni-kiel.de/kiel2014 Living Together: Planets, Stellar Binaries and Stars with Planets 8 - 12 September 2014 Litomysl Castle, Litomysl, Czech Republic http://astro.physics.muni.cz/kopal2014/ From Galactic to Extragalactic Star Formation 8 - 12 September 2014 Marseille, France http://gesf2014.lam.fr Towards Other Earths II. The Star-Planet Connection 15 - 19 September 2014 Portugal http://www.astro.up.pt/toe2014

66 Star Formation Across Space and Time 11-14 November 2014 Noordwijk, The Netherlands http://congrexprojects.com/14a09/

Other meetings: http://www1.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/meetings/

Short Announcements

Fizeau exchange visitors program - call for applications

Dear colleagues! The Fizeau exchange visitors program in optical interferometry funds (travel and accommodation) visits of researchers to an institute of his/her choice (within the European Community) to perform collaborative work and training on one of the active topics of the European Interferometry Initiative. The visits will typically last for one month, and strengthen the network of astronomers engaged in technical, scientific and training work on optical/infrared interferometry. The program is open for all levels of astronomers (Ph.D. students to tenured staff). Applicants are strongly encouraged to seek also partial support from their home or host institutions. The deadline for applications is March 15. Fellowships can be awarded for missions starting in May 2014. Further informations and application forms can be found at www.european-interferometry.eu and vltischool.sciencesconf.org The program is funded by OPTICON/FP7. Please distribute this message also to potentially interested colleagues outside of your community! Looking forward to your applications, Josef Hron & Laszlo Mosoni (for the European Interferometry Initiative) Electronic mail: fi[email protected]

67 New Books

50 Years of Brown Dwarfs From Prediction to Discovery to Forefront of Research Ed. Viki Joergens

Today we know that brown dwarfs are ubiquitous, and hundreds – both young and old – are known by now. But it is less than 20 years since the first such objects were discovered, despite the theoretical prediction of their existence 50 years ago. This little book goes behind the scene of the pioneering works that formed the foundation for today’s thriving research into brown dwarfs. The first two chapters discuss the theoretical predictions of brown dwarfs by Kumar and by Hayashi and Nakano, followed by a discussion of how brown dwarfs got their name. Then comes three chapters providing personal accounts of the efforts that went into the discovery of the first three brown dwarfs by the discovery teams. The book closes with two chapters on the present status of observations and theory of brown dwarfs by two leading experts. The following lists the chapters of the book: 1 The Theoretical Prediction of the Existence of Brown Dwarfs by Shiv S. Kumar Viki Joergens 2 Pre-main Sequence Evolution and the Hydrogen-Burning Minimum Mass Takenori Nakano 3 Brown is Not a Color: Introduction of the Term “Brown Dwarf” Jill Tarter 4 1 and the Discovery of Brown Dwarfs Rafael Rebolo 5 The Discovery of the First Lithium Brown Dwarf PPl 15 Gibor Basri 6 Companions of Stars: From Other Stars to Brown dwarfs to Planets and the Discovery of the First Methane Brown Dwarf Ben R. Oppenheimer 7 Ultracool Objects: L, T, and Y Dwarfs Michael C. Cushing 8 Latest News on the Physics of Brown Dwarfs Isabelle Baraffe

Springer 2014, ISBN 978-3-319-01161-5 168 pages, hardcover US$99.00 Available from http://www.springer.com/astronomy/book/978-3-319-01161-5

68