264 — 11 December 2014 Editor: Bo Reipurth (Reipurth@Ifa.Hawaii.Edu) List of Contents

Home , Chamaeleon complex, L1014, Trihydrogen cation

THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 264 — 11 December 2014 Editor: Bo Reipurth ([email protected]) List of Contents

The Star Formation Newsletter Interview ...... 3 My Favorite Object ...... 6 Editor: Bo Reipurth [email protected] Perspective ...... 11

Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers ...... 17 [email protected] Abstracts of Newly Accepted Major Reviews . 51 Technical Assistant: Hsi-Wei Yen Dissertation Abstracts ...... 52 [email protected] New Jobs ...... 54

Editorial Board Meetings ...... 57 New and Upcoming Meetings ...... 59 Joao Alves Alan Boss Jerome Bouvier Lee Hartmann Thomas Henning Cover Picture Paul Ho Jes Jorgensen NGC 1333 is located at a distance of 235±18 pc Charles J. Lada (determined to the source SVS 13, Hirota et al. Thijs Kouwenhoven PASJ 60, 37, 2008) and most of the cluster mem- Michael R. Meyer bers have an age less than ∼3 Myr, but with a large Ralph Pudritz spread from newly born Class 0 sources to stars Luis Felipe Rodr´ıguez around 10 Myr old. Numerous Herbig-Haro ﬂows Ewine van Dishoeck criss-cross the central cloud core. Hans Zinnecker The image is composed of data from Subaru, DSS, The Star Formation Newsletter is a vehicle for NOAO, and color images by Robert Gendler. fast distribution of information of interest for as- Image assembly and processing by Robert Gendler tronomers working on star and planet formation and Roberto Colombari. and molecular clouds. You can submit material http://www.robgendlerastropics.com for the following sections: Abstracts of recently http://www.astrobin.com/users/rob77/ accepted papers (only for papers sent to refereed journals), Abstracts of recently accepted major reviews (not standard conference contributions), Dis- sertation Abstracts (presenting abstracts of new Ph.D dissertations), Meetings (announcing meetings broadly of interest to the star and planet for- Submitting your abstracts mation and early solar system community), New Jobs (advertising jobs speciﬁcally aimed towards Latex macros for submitting abstracts persons within the areas of the Newsletter), and and dissertation abstracts (by e-mail to Short Announcements (where you can inform or re- [email protected]) are appended to quest information from the community). Addition- each Call for Abstracts. You can also ally, the Newsletter brings short overview articles submit via the Newsletter web inter- on objects of special interest, physical processes or face at http://www2.ifa.hawaii.edu/star- theoretical results, the early solar system, as well formation/index.cfm as occasional interviews. Newsletter Archive www.ifa.hawaii.edu/users/reipurth/newsletter.htm

2 about the interstellar medium and then to start publishing papers on cloud models in 1973. Bill and I were helped Al Glassgold by a visit with the Townes group at UC Berkeley in the in conversation with Bo Reipurth summer of 1972. Q: Has your physics background been an advantage for your work? A: My physics background has indeed been a primary driver of my research in astrophysics. Many of my papers have been devoted to the clarification and calculation of physical processes, or to providing the microscopic background for complex astrophysical models. A good example of the latter are the more than a dozen papers with Frank Shu and his collaborators, especially his students Joan Najita, Susana Lizano and Sienny Shang with whom I continue to be close. In the papers dealing with the meteoritic implications of the X-wind model, my nuclear physics background proved helpful. Q: You started out writing a series of papers in the sev- Q: You came to astronomy from a background in physics. enties with Bill Langer. An especially noteworthy paper What motivated that move? from 1974 discussed models of diffuse clouds. What were A: The move actually took years and was stimulated by the main results? several interactions with various colleagues. My early re- A: This paper was the first PDR (photo dissociation research in theoretical physics dealt with nuclear scattering, gion) model. The observational motivation for us was the and later I branched out into atomic scattering and ap- early Copernicus UV absorption line studies of interstellar plications of the new many-body techniques to nuclear, diffuse clouds, especially the thicker ones with significant atomic and low temperature physics. Early on this led to amounts of molecular hydrogen. Many others joined in several quantitative treatments of spin-exchange scatter- developing this subject, and the scope of the model was ing between hydrogen atoms, important for understanding immensely extended by the 1985 papers by Tielens and astronomical 21cm radiation. A work more focused on as- Hollenbach. The detailed application of the model to dif- trophysics was a paper entitled ’Anisotropic Superfluidity fuse clouds was greatly advanced by my student, Steven in Neutron Star Matter’, published in the 1970 Physical Federman, and his collaborators. In addition to modeling Review Letters with my student Mark Hoffberg and NYU the clouds, Steve has been active in observing them, and faculty colleagues, Bob Richardson and Mal Ruderman. In he also carried out theoretical and experimental studies of 1964, the Russian theorists Ginzburg and Kirzhnitz had the underlying atomic and molecular physics. suggested that neutron stars are superfluid, and Ruder- Q: Have laboratory studies been helpful in your work on man asked whether this idea could be pursued further. interstellar clouds? I responded positively on the basis of the recent theory of the superfluidity of liquid He-3 based on the Bardeen, A: The discovery of extraterrestrial molecules was a chal- Cooper and Schrieffer (BCS) theory of superconductivity. lenge to both observers and theorists simply because their Unlike the spin-zero electron pairs relevant for supercon- spectra and physical properties were often poorly known, ductivity, the special properties of the nuclear forces led to if at all. As our studies of interstellar and circumstellar 3 P2 neutron pairs as the basis of anisotropic superfluidity matter become progressively more detailed, the results of of neutron star matter. This was Mark Hoffberg’s Ph.D. laboratory studies are still needed. Hardly a day goes by thesis, and it represented the first quantitative treatment without my searching, often unsuccessfully, for some as- of superfluidity in neutron stars. pect of molecular astrophysics. For example, modeling dense molecular regions requires information, now often At this point I was in regular contact with Patrick Thad- lacking, on the excitation of the products of chemical re- deus who was becoming active in the new field of sub-mm actions and of dissociative recombination. The needed radio astronomy. I had met him some ten years earlier laboratory studies are carried out by both chemists and when he was still a graduate student in Charlie Townes physicists, and the experiments are demanding and costly. lab at Columbia University which I visited in connection Sufficient and durable support is needed for young scien- with my interest in new techniques for atomic physics. An tists to develop careers in this area. I fear that this support equally important interaction occurred with the arrival of is now not strong enough. Bill Langer at NYU in 1971. Together we began to learn

3 Q: In 1991 you and your collaborators explored the for- atively short timescales in the inner few AU of the disks mation of molecules in protostellar winds. Do models and around T Tauri stars. This prediction is consistent with observations agree? detections of warm and hot water in these disks obtained A: The 1991 paper with Huggins and Mamon argued that with Spitzer and other instrumentation. It does not rule SiO and other molecules were synthesized in the nascent, out other processes, such as vertical and radial mixing of inner outflows of young protostars. In the ensuing decades water and water ice, but it does indicate that the inner extensive observations of SiO and some other species have regions of protoplanetary disks are able to rapidly process been made of bipolar outflows with mm arrays such as gas phase oxygen into water. The existence of substantial Plateau de Bure, CARMA and SMA. But a resolution of water vapor in the inner few AU of these disks depends a fraction of an arcsecond isn’t enough to get to the heart on the details of the chemistry, which in the case of OH of the matter, i.e., the origin of the jet that drives the and water is sensitive to the gas temperature and to the outflows. Future observations with ALMA at the highest formation of molecular hydrogen. resolution may finally do the job. Of course the models Q: In one of your most recent papers you have re-visited of the outflows need to be improved in light of significant cosmic-ray and X-ray heating of clouds and disks. What advances is astrochemistry over the intervening years. Si- are the new physical ingredients in these calculations? enny Shang at ASIAA is pursuing this line of research and A: The main new direction is a more complete analysis also encouraging the appropriate observations. of the chemical reactions induced by the primary prod- + + Q: Did the discovery of extreme overabundances of for ex- ucts of X-rays ionization, the H2 and H3 ions. We have ample SiO and CH3OH in the L1157 outflow and some recently extended this idea to FUV photodissociation in other flows come as a surprise? molecular regions. The heating from the absorption of A: More delight than surprise! FUV radiation by neutral species in dense molecular gas is dominated by the energy yield from the chemical reactions Q: Your well cited paper from 1997 deals with X-ray ion- induced by the products of photodissociation or photoionization of protoplanetary disks, a study you followed up in ization. The total heating combines heating from the slow- 2004. What is the state of this field today? ing down of the initial photo fragments (“direct” heating) A: The role of X-rays is now much better understood in and the conversion of the energy released by the ensuing the context of the further model studies in 2004 of the chemical reactions (“chemical” heating). The products atmospheres in the inner regions of protoplanetary disks, from both processes are often excited and, if the density work done in collaboration with Joan Najita and my stu- is high enough, the excitation energy can be converted dent Javier Igea. Our current picture of the inner disk into heating by collisional de-excitation. A good example atmosphere is that it consists of a relatively hot top layer is provided by molecular hydrogen where FUV absorp- (∼ 5000 K), a warm molecular region (∼ 300 − 1000 K), tion yields electronically excited molecules whose fluores- and a cool region below (< 300 K). The X-rays do not cent decay leads to excited ro-vibrational levels. Another play a major role in heating, but they are responsible for example is the photoionization of atomic carbon, where + + + + generating hydrogen ions (H , H2 . H3 ; He ) and the the small standard heating of 1.4 eV per photoionization heavier, easier to observe, molecular ions such as HCO+ comes from the kinetic energy of the products C+ and + − + and N2H . Once the FUV photons in the warm molecu- e , but the chemical reactions induced by the C ion can lar layer are absorbed, the X-ray generated ions become generate much more heating. the dominant agents for regulating molecular abundances, Q: What do you consider the main outstanding problems e.g., by destroying molecules snd by producing reactive currently in understanding the heating and cooling pro- neutral and ionized atoms and more complex radicals. cesses in disks and clouds? Q: A few years ago you studied the formation of water in A: I’ll focus on protoplanetary disks because they have the warm atmospheres of disks, and among other findings been the main focus of my research in recent years. Study- you noted that it may not be necessary to invoke transport ing their physical properties can help us understand molec- of water from cooler to warmer regions. Is this of relevance ular gas in general. The heating and cooling of protoplan- for the early solar system? etary disks remains a challenge. The gas in these disks A: The evolution of water over the lifetime of a proto- covers a wide range of densities and temperatures, ranging 6 16 −3 planetary disk up to and after the formation of planets is from nH = 10 − 10 cm and T = 20 − 5000K. Thus basic for understanding the composition of planetary at- all of the familiar phases of the ISM are encountered – mospheres, including our own solar nebula and the Earth’s and more. What is unusual about these disk atmospheres oxygen-rich atmosphere. Further studies of water in pro- is the very high densities in the warm molecular regions toplanetary disks that include FUV heating, dissociation relevant for spectroscopic observations. This means that and absorption show that abundant water forms on rel- familiar processes from the study of more diffuse regions

4 may need revision, and of course new processes may also we are still at the beginning of efforts to construct phys- enter. Although protoplanetary disks have been observed ically sound models of protoplanetary disks that will be at many wavelengths, many of the most interesting re- relevant in an era when the observations will be made sults such as the detection of water in the near- and mid- with greatly improved spatial resolution that can probe infrared, were made at low spatial resolution, making com- the planet forming region of these disks. parisons between theory and observation difficult. The re- Q: For students who wish to be involved in such future cent mm observations of HL Tau with a spatial resolution modeling as you just mentioned, what physics background of 35 milli-arcseconds (5 AU) fill us with hope for more do you think is most important to acquire to be able to fine scale observations of protoplanetary disks. enter this fruitful field? The 2004 paper you mentioned earlier with Najita and The opportunities provided by ALMA challenge theorists Igea was called ’Heating Protoplanetary Disk Atmospheres’. to develop more sophisticated models, as indeed they should. It should have ended with a question mark, and a current The new generation modeling of protoplanetary disks must reconsideration of this subject with Joan Najita and Mate treat the hydrodynamics and the physics (and chemistry) Adamkovics may well have something like this corrected on a unified basis. To build strength in the latter area, it is title. The most important heating mechanism for the ISM, important for graduate students to study in depth atomic grain photoelectric heating, has also been invoked by many and molecular physics and the physics of radiation. Much modelers of protoplanetary disk atmospheres. However, it of what is required in disk modeling is inter-disciplinary, is inadequate unless a very large fraction of the available and the standard courses offered to students are often too carbon is in small carbonaceous particles (PAHs). But the narrow. Some broad inter-department curriculum devel- occurrence of PAHs in these regions is uncertain because opment would be very welcome. the limited, existing observations do not have the spatial resolution to determine the location of the PAHs. In the 2004 study, we argued that mechanical heating, probably fueled by viscous dissipation, might heat protoplanetary disk atmospheres. We argued that the usual α thin disk heating should be considered as a three-dimensional quantity and that it should be large in disk atmospheres. This picture has since been supported by simulations of the magneto-centrifugal instability (MRI) by Turner and Hirose (2011) and Bai and Stone (2013), among others. When incorporated into our disk model, accretion heating dominates the heating, and it gives inner disk temperatures suggested by the infrared observations. More recently we have been exploring FUV heating by molecules, instead of just photoelectric heating by grains discussed above. Photochemical heating by the water molecule is quite interesting in this respect. At the top of the molecular region at 1 AU, the photochemical heating rate for water is about four times larger than accretion heating. However, with increasing depth the dissociating radiation becomes optically thick and accretion heating dominates. Before strong water self-shielding sets in, the molecular transition region may be dominated by FUV photochemical heating. More generally, our studies indicate that the heating of protoplanetary disk atmospheres depends on the region, and that it may involve more than one process at any given location. To answer the question, ’What Heats Protoplanetary Disk Atmospheres?’, one has to consider several competitive heating processes, in particular the role of PAHs, accretion heating, and photochemical heating. A paper that attempts to resolve this issue is now under preparation with my collaborators, Mate Adamkovics and Joan Najita. But

5 derstanding of TTauri disks, I arrived at IRAM-Grenoble as a young post-doc in December 1991 with a new research My Favorite Object project to work on: the physics of the recently discovered GG Tau A: TTauri disks. One Ring to Rule Them All (thanks to J.R.R. Tolkien) Anne Dutrey

Figure 1: The four components of GG Tau as seen in an 0.81 µm HST image. North is up and east is left. The closest pair (A) has a separation of 0.26” and the wider one (B) is a 1.48” binary. From White et al. (1999). 1 The Early Times

Located at about 140 pc, the young (∼ 1 Myr) TTauri system GG Tau has been known as a hierarchical stellar system ever since the early nineties (Leinert et al 1991). At that time, it was known to consist of a pair of binaries GG Tau A and GG Tau B, the wide binary GG Tau AB being separated by 10′′ in the plane of sky. The binary GG Tau B has an apparent separation of 1.4′′ and GG Tau A, the focus of this review, of 0.26′′. The four components span spectral types from K7 to M7, and the least massive of these is a brown dwarf (White et al. 1999). The 1.3 millimeter flux of GG Tau A measured by the IRAM 30-m telescope by Beckwith et al 1990 revealed that it is the second brightest millimeter-wavelength TTauri source (HL Tau is the brightest), making it an excellent target for the generation of mm telescopes which started to oper- Figure 2: From Simon and Guilloteau 1992. 2.7mm ob- ate in the nineties. Skrutskie et al 1993 observed it in CO servations of the dust disk surrounding GG Tau A. The J=1-0 using the Nobeyama 45m and detected the double contour spacing is 2mJy per beam.The beam size is 2.4” o peaked profile which is now recognized as characteristic by 1.8” with P.A. 50 . of a rotating disk. A CO J=1-0 map made by Kawabe et al 1993 also showed a displacement of the centroids of the red-shifted and blue-shifted line emission which can be In the fall of 1991, motivated by the very strong mm-wave interpreted as due to rotation. They also found the CO continuum emission of GG Tau A, Michal Simon wrote disk was large and thus necessarily circumbinary and they a successful PdBI proposal to map it. The observations, suggested the possible existence of a central hole produced carried out during winter 1991/1992, were made on the by tidal interactions between the binary and the disk. Ko- long baseline configuration. Stephane Guilloteau made a erner et al 1993 also published the first 13CO J=2-1 map preliminary data reduction and discovered that the source made with OVRO. In the midst of this rapidly growing un- was not seen in the image! He also noticed that the noise was significantly higher than the thermal contribution in

6 Figure 3: Left panel: continuum distribution in the GG Tau A disk at 2.7mm (false color) and three velocity channels of the 13CO J=1-0 observations from PdBI. From Dutrey et al 1994. Middle panel: the same at 1.3mm and in 13CO J=2-1. From Guilloteau et al 1999. Right panel: IR image at 1.2µm of the dust in the scattered light emission. From Roddier et al 1996. the center of the map. He concluded that the source was Tau A was then re-observed on the long baselines and the completely resolved on the long baselines and the project resulting map magically showed again a velocity gradient should be continued in compact configuration. Fig.2 shows suggesting rotation. We also found a way to recover the the final image (Simon and Guilloteau 1992). Due to poor corrupted data and the final image had the impressive and very incomplete uv coverage (baselines between 50 number of 27 baselines, making it among the best mm im- and 150m were missing), the algorithm CLEAN could not ages produced at that time. The 13CO J=1-0 and 2.7mm properly recover the source structure even though the to- thermal dust maps (Dutrey et al. 1994) are presented in tal flux was conserved (short baseline contribution). The Fig.3. authors concluded that the source was resolved in one direction but that these first observations could not indicate which one. 2.2 First Gas and Dust Modeling Left panel of Fig.3 shows the thermal dust emission at 2.7mm (false color) and three velocity channels, blue-shifted, 2 A Ring or a Disk ? systemic velocity and red-shifted, of the 13CO J=1-0 emission. The CO disk extends up to an outer radius of 800 au. 2.1 A Series of Misfortune and Luck The dust distribution does not appear centrally peaked, suggesting a central hole which was confirmed by the fit. The next step was to search for CO gas and possible Kep- The central hole was marginally resolved in the CO map lerian rotation. The new observations were carried out in and the best model clearly confirmed that both the gas 13 winter 1992/1993. We chose to observe the CO J=1-0 and dust disks were truncated at an inner radius of 180 au. 12 line instead of the more abundant CO because of the The interior truncation of the disk could be attributed to atmospheric O2 line at 118 GHz which increases the at- tidal interactions with the central binary (Artymowicz et mospheric opacity around 115 GHz. al 1991). The results from compact configuration was very promis- The observations revealed that most of the dust and gas 13 ing because in the CO map, the centroid of the emission emission is located in a very narrow ring of 80 au width, of each velocity channel was moving exactly like expected extending from 180 to 260 au with relatively sharp edges. for a disk in rotation. However the final image which in- The best fit of both the dust and 13CO modeling was cludes the medium baselines was very disappointing: the obtained for a gaussian shape. Beyond a radius of 260 au, rotation had apparently disappeared. However, a few days the CO brightness of the outer disk was well reproduced by later, a shift in velocity in the absorption lines observed to- a radial power law. The narrow ring contains 90% of the wards 3C111 compared to the Kitt Peak spectra revealed dust emission, with only 10% extending beyond 260 au. that the PdBI synthetizer had indeed been unlocked. GG

7 With about 0.13-0.15 M⊙, the total (gas+dust) mass, es- 3.2 Millimeter versus NIR Images timated from the optically thin dust emission (taking the absorption coefficient from Beckwith et al 1990 and as- GG Tau A was also among the first disks to be imaged in suming a gas-to-dust ratio of 100), makes this disk among the Near Infrared (NIR) scattered light. Using the adap- the more massive TTauri disks. Its mass represents about tive optics system they had developed, Roddier et al 1996 10% of the total stellar mass. The 13CO data and the op- observed the dust ring in the Near Infrared at the CFHT. tically thinner C18O J=1-0 and J=2-1 upper limits (from The right panel of Fig.3 shows their image at 1.2µm. The the IRAM 30-m telescope) also suggested that the CO ring is brighter in its northern part, the area pointing to- gas was depleted by about 100. The gas temperature was wards us, and has an inner edge at 180 au, as previously about 20-25 K inside the ring. derived from the mm images, definitively confirming the edge sharpness and the tidal truncation. Finally, the modeling of the CO line also nicely confirmed that the ring is in Keplerian rotation around the central The central stars also do not appear located in the cen- binary. ter of the ring. By comparing the 1.2µm optically thick emission of the dust seen in scattered light with the image of the optically thin thermal dust emission at 1.3mm, we 3 The Central Cavity conclude that since the NIR emission is optically thick, the vertical ring thickness at radius 180 au is of the order of 120 au and this thickness also explains the apparent shift 3.1 Sub-Arcsecond Imaging of the stars from the ring center (Guilloteau et al 1999). In 1996, the IRAM array was upgraded, the new receivers Interestingly, Roddier et al 1996 noticed that the central were dual frequency at 115 and 230 GHz and baselines hole does not appear completely devoid of dust, this fact were extended to ∼400m. Observing at 230 GHz using was confirmed by other scattered light images of the dust the new baselines increases the angular resolution by a at NIR or optical wavelengths (e.g., Silber et al 2000, Krist factor 4. The middle panel of Fig.3 presents the new et al. 2005, see Fig. 4). GG Tau A images in 13CO J=2-1 and in continuum at 1.3mm, obtained in winter 1996/1997 (Guilloteau et al 1999). Compared to the left panel of the same figure, the central hole is fully resolved both in line and in continuum. The three velocity channels of 13CO J=2-1 closely follow the dust ring even if the CO emission is significantly more extended. HCO+ J=1-0 and the dust emission at 3.4mm were also mapped. The best modeling of the lines and dust emissions essentially confirmed the previous analysis, in particular, the steepness of the inner and outer edges of the ring. The new data allow the derivation of the gas temperature because the 13CO J=2-1 emission is optically thick in the ring. At 180 au, the gas temperature is ∼ 35 K −0.9 and the best fit gives Tk(r)=20 × (r/300au) K, confirming that most of the CO disk is cold. The continuum visibilities confirm that about 10-15% of the flux density Figure 4: An HST image of GG Tau A (Krist et al. 2005). arises from the outer disk. Moreover at 1.3mm, an unresolved central source is seen at the level of about 10mJy, 12 suggesting the presence of one or two inner circumstellar A new image of the CO J=2-1 obtained with the IRAM disks associated with GG Tau Aa and Ab. array in 2001 also revealed the presence of some resid- ual unresolved 12CO gas inside the cavity (Guilloteau In hindsight, we realized that we were very lucky in 1992 and Dutrey 2001) as predicted by theory and hydrody- to select 13CO instead of 12CO. The central cavity, which namical simulations of circumbinary disks (e.g. Bate and was the first to be detected in a TTauri disk, was both seen Bonnell 1997, Artymowicz and Lubow 1996). However, in the 13CO and dust maps, although marginally resolved. resolving the streamers of gas and dust falling down from If we had observed in 12CO J=1-0, it would have been the outer reservoir of material onto the circumstellar in- difficult to convince our colleagues that the hole in the dust ner disks which would not survive without regular replen- distribution was real and not an observational artifact on ishment was beyond the capabilities of the existing mm the long baselines. arrays. Many questions were left hanging for nearly 15 years.

8 4 The ALMA Era or streamer made of several clumps. The outer circumbinary disk is hardly seen. This is likely due to both an During a meeting organized in June 2011 in honor of Mike H2 density insufficient to thermalize the transition and Simon, at Stony Brook University, Tracy Beck presented the lack of short spacings. At large distances from the preliminary images of H2 at 2.12µm of GG Tau obtained three stars, the kinematics of the CO J=6-5 is Keplerian, at Gemini North. These images revealed the existence of the gas being in rotation around the triple stars. Near the hot gas in the cavity of GG Tau A. Beck et al (2012) found stars the velocity pattern is disturbed with motions partly that a significant fraction of the H2 gas is hot (∼ 1000 − compatible with infall. We also detect some CO gas as- 1700 K) and that is likely due to heating by accretion sociated to the disk orbiting GG Tau Aa. The clumps shocks. Stimulated by these observations, we decided to seen in CO J=2-1 emission are relatively cold (∼ 35 K) join our forces to study the GG Tau system by a multi- and optically thick. The clumps traced by CO J=6-5 are wavelength approach. likely optically thin and correspond to warmer gas (70 K), particularly at the interface between the streamer and the inner disk of Aa. The mass of each CO J=6-5 clump is −5 4.1 A Triple System about ∼ 5 · 10 M⊙. Such a mass reaching the Aa disk may disappear in at most 5000 years assuming a mini- −8 In 2013 we observed the stellar system using VLT/NaCo mum accretion rate of 10 M⊙/yr. In 1 Myr, at least 200 and VLTI/PIONIER at ESO and discovered an additional fragments of similar mass must have been accreted to sus- −3 low-mass companion orbiting GG Tau Ab, and located at tain the 10 M⊙ disk orbiting Aa (the disk mass being projected separation of the order of 4.5 au (Di Folco et estimated from the dust emission). al 2014). Adding the mass of the new star to the best determination of the two others leads to a better agree- The dust emission from the circumbinary ring is uniform ment with the dynamical mass inferred from CO J=2-1 and very well resolved. We analyzed the 0.5 mm ALMA measurements. Moreover, the existence of this third com- image with existing 1.3 and 3.4 mm continuum maps of ponent also explains why Pietu et al 2011 reported the de- the ring and derived the ring temperature profile: Td(r)= × −1.1 tection of a mm dust disk only around GG Tau Aa. Any 13.8 (r/200au) K. This corresponds to 8.5 K at a circumstellar disk around GG Tau Ab would be tidally radius of 300 au. Since the 0.5 mm emission is departing from the Rayleigh-Jeans domain, this derivation is almost truncated at a radius no greater than 1-2 au. The new −0.9 triple system is shown in Fig.5, middle panel. independent of the dust properties. A steep slope (r ) was also derived from the 13CO gas distribution, but with a warmer gas temperature of 20 K at 300 au. All re- 4.2 First ALMA Images sults are consistent with the existence of a dense dust disk which intercepts most of the stellar light at its inner edge We applied to ALMA, and received our data in Febru- (∼ 180 au), the material beyond is colder because of the ary 2012. The observations (about 40 minutes on source) shadow and presents a steep temperature profile. The CO were made with 23 antennas giving 253 baselines, almost a molecules are trapped on grains in the mid-plane because factor 10 more compared to the interferometric data from their temperature is below the CO freeze-out point (17 K). Dutrey et al 1994. During the reduction process, we found CO gas is only present in the heated upper layers of the that (again!) a velocity shift corrupted the data. Despite disk. several attempts, its origin could not be found but its mag- 12 Finally, both the CO J=2-1 and J=6-5 maps (Fig.5) show nitude was determined by correlation with the CO J=2-1 a very puzzling unresolved hot spot located at the ring data. outer edge (∼ 250 au) at a position angle of ∼ 120o (north Left panel of Fig.5 shows the integrated area of the CO to east). This emission may originate from the progenitor J=6-5 observed with ALMA in the GG Tau A system of a sub-stellar object similar to the planetary-mass com- (false color) with an angular resolution of 0.25” or 35 au. panion imaged around a low-mass binary star by Delorme The dust thermal emission at 0.5mm (black contours) is et al (2013). Such a companion would naturally explain seen in the ring and in the circumstellar disk surrounding the confinement of 80% of the circumbinary mass in the the single star GG Tau Aa. The right panel shows the CO narrow ring of 80 au width. We do not detect a gap at J=2-1 integrated area and the dust emission at 1.3mm the interface between the ring and the outer disk , but observed with the IRAM array in winter 2006. The CO the existing 13CO data shows at this radius (∼ 260 au) a J=6-5 and 1-0 results were presented together (Dutrey et ring/outer disk density contrast of the order of ∼25 which al 2014). can be attributed to an unresolved gap. Most of the CO J=6-5 emission arises inside the cavity Our results demonstrate at least two reasons why the GG and shows the morphology of an inhomogeneous filament Tau system is interesting. It is a fundamental object to

9 Figure 5: Left panel: integrated area of CO J=6-5 and 0.5mm dust emission in black contours observed with ALMA (Dutrey et al 2014). The beam size is about 0.25” or 35 au. Middle panel: the new triple stellar system (Di Folco et al 2014). Right panel: same as left panel but for the CO J=2-1 line and 1.3mm dust emissions observed with PdBI. Copyright: Nature/ALMA/ESO/IRAM/CNRS/Universit´ede Bordeaux.

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10 ning in the 1980s (e.g., Rydgren & Vrba 1983, Herbst et al. 1983, Rydgren et al. 1984). Periodic variability predom- Perspective inated among the WTTS (Herbst & Koret 1988 and references therein), whereas the cause of brightness modula- The Many Facets of Young tion in the classical T Tauri stars (“CTTSs”) was the sub- Star Variability ject of speculation. For example, Rydgren & Vrba (1983) mentioned variable obscuration by dust clouds passing Ann Marie Cody over the stellar disk but favored a model involving hot plages on the stellar surface. Appenzeller & Dearborn (1984) posited that changing surface magnetic fields were involved in the brightness changes via modulation of active regions. Bertout et al. (1988) instead invoked hot spots caused by the infall of accretion material. The pace of variability monitoring picked up further in the 1990s, with in-depth studies of starspot properties and rotation rates (Bouvier et al. 1995), simultaneous photometric and spectroscopic campaigns (e.g., Vrba et al. 1993), high resolution spectroscopic monitoring (e.g., Johns & Basri 1995). Bouvier et al. (1999) reported eclipses by circumstellar material around AA Tau. Other groups under- took near-infrared monitoring to probe cooler phenomena (e.g., Horrobin et al. 1997, Hodapp 1999, Skrutskie et al. 1996, Carpenter et al. 2001). Suggestions as to the cause 1 Historical background of variability included changes in the structure of accreting material at the disk or stellar surface (Kenyon et al. Photometric variability is one of the defining characteris- 1994, Simon et al. 1990), variations in geometry, opacity, tics of young, low-mass stars in the 1–10 Myr range. Its or temperature of circumstellar gas and dust, or varying study dates back to the mid-1800s, when W. C. Bond iden- levels of extinction by surrounding material (e.g., Schmelz tified the first variable star in the Orion Nebula, AF Ori 1984). (see Herbig 1982). Further variables were picked up on the To aid in variability classification efforts, Herbst et al. Harvard plates by H. S. Leavitt, and published in Picker- (1994) assembled a comprehensive catalog of the UBVRI ing & Leavitt (1904). Follow-up studies identified addi- behavior of 80 T Tauri stars. This study was among tional stars exhibiting brightness changes of up to three the first to highlight multiple distinct variability mech- magnitudes and associated with molecular clouds. With anisms in T Tauri stars: periodic behavior due to persis- prototype T Tauri, these so-called “nebular variables” dis- tent hot and cool spots, irregular brightness changes due played irregular light curves unlike any other class of vari- to variable accretion, as well as month- to year-long fad- able; examples are shown in Figure 1. They had bright ing events attributed to circumstellar obscuration. This emission in hydrogen and calcium II, and these lines were latter phenomenon was seen only in the early type stars, also noted to fluctuate with time (Joy 1945). Members with UX Ori as their prototype. Prior to this work, many of the new class displayed ultraviolet excesses – initially authors attempted to attribute CTTS variability to a sin- interpreted as an indicator of a deep chromosphere. Only gle cause, only to find inconsistent results. The Herbst et a decade later did it become clear that these were pre- al. (1994) catalog formed the basis for our modern frame- main sequence stars (Ambartsumian 1954, Herbig 1962) work of optical variability in young stellar objects (YSOs), surrounded by accretion disks (Bertout et al. 1988). An providing a taste of the data deluge that was to come. infrared excess revealed the presence of warm circumstellar dust (e.g., Strom et al. 1972). These objects represented the end state of star formation, with remaining gas accreting onto the central star. 2 Cool spots, hot spots, and stellar Photometric characterization of the pre-main sequence T rotation Tauri stars and their spectral energy distributions spurred numerous monitoring campaigns in the optical and even- Despite reports by Herbst et al. (1994) and Bouvier et al. tually the near-infrared. Both classical (i.e., accreting) T (1999) of fading events suggestive of circumstellar obscu- Tauri stars and their weak-lined counterparts (“WTTSs”) ration, attention to young star variability remained largely were subjected to intensive time series monitoring begin- on starspots as the primary mechanism. In individual

11 et al. 2010). Attribution of periodic light curve signatures to spot modulation enables derivation of photometric rotation periods. Investigation of the disk locking question has produced conflicting results, with some authors finding no connection between rotation period and disk or accretion indicators (e.g., Stassun et al. 1999, Makidon et al. 2004, Littlefair et al. 2005), and others detecting a correlation between rotation and either Hα equivalent width (a proxy for accretion) or (near-)infrared excess (e.g., Herbst et al. 2002, Rebull et al. 2006, Rodriguez-Ledesma et al. 2010). Complications in the testing of disk locking theory have arisen because there appears to be a mass dependence to rotation rates (e.g., Littlefair et al. 2005). In addition, the Figure 1: Young stars in the 1–10 Myr range were discov- time dependent near-infrared excess is an imperfect indi- ered to be variable in the mid-1800s. Pictured here are cator of disk presence, and does not have a perfect cor- some of the early light curves– in this case for target RW respondence with accretion indicators such as Hα, which Aur (as published by Joy 1945). Initial monitoring did may fluctuate with time. It can also be argued that rota- not provide enough data points to determine light curve tion rate measurements are biased by the fact that rapidly morphology, but it did reveal that these objects could vary accreting objects might only display irregular variability. with amplitudes up to 3 magnitudes on timescales of min- While for many analyses, high-amplitude aperiodic pho- utes (e.g., flares) to years (e.g., outbursting events). tometric behavior was considered “contamination” for rotation rate samples, several studies did highlight it as an interesting phenomenon in its own right. Both Cohen et cases, multi-band photometry revealed whether cool or hot al. (2004) and Littlefair et al. (2005) identified stars in spots on the stellar photosphere was more consistent with IC 348 with irregular light curves, including some with periodic behavior in light curves. Hot spots were a natu- fading events of up to one magnitude, reminiscent of the ral consequence of the magnetic accretion flow model put UX Ori class. They attributed these events to occul- forth by Königl in 1991. In contrast to the earlier bound- tations by dust clouds along the line of sight. Scholz ary layer model (Lynden-Bell & Pringle 1974), flow along & Eislöffel (2004, 2005) as well detected high-amplitude, magnetic field lines from the inner disk to the stellar sur- quasi-periodic variability among a small fraction of their face explained both spectroscopic evidence of free-falling σ Orionis and ǫ Orionis monitoring samples, suggesting material (Edwards et al. 1994, Hartmann et al. 1994) and that hot spots formed in the presence of unsteady accre- the slow rotation rates of T Tauri stars, which required a tion flow were responsible for this light curve behavior. braking mechanism. It also naturally produced hot spots In Cody & Hillenbrand (2010), we found that ∼30% of where shocked gas encountered the star at its magnetic all monitored low-mass I-band variables in the σ Orio- poles. nis cluster displayed erratic aperiodic behavior, of which Given this magnetospheric accretion model, a key ques- ∼20% involved prominent fading events on hour-to-day tion has been whether magnetic fields lock young stars timescales. This work showed that high precision, high to their disks, transferring angular momentum outward cadence photometric monitoring has the capability to re- and thereby preventing stellar spin-up until the disk dis- veal potentially important morphological information in perses (e.g., Shu et al. 1994). Initial studies (e.g., Bouvier light curves. et al. 1993, 1995) reported that photometric rotation rates Additional insights into aperiodic variability came when were systematically different between WTTSs and CTTSs. photometric monitoring expanded from the optical to near- With the advent of wide-field CCD detectors and extensive infrared. Carpenter et al. (2001, 2002), Eiroa et al. (2002), characterization of star cluster members, further opportu- Alves de Oliveira & Casali (2008), Scholz et al. (2009), nities to test this idea arose. Many star formation regions and Parks et al. (2013) were all able to study the color have now been monitored photometrically, inluding the variability in these bands, finding that some objects be- Orion Nebula Cluster (e.g., Stassun et al. 1999, Rebull came redder when fainter, while others became bluer. The 2001, Rebull et al. 2006, Rodriguez-Ledesma et al. 2010), wide variety of color behavior among T Tauri stars in the Chamaeleon I (Joergens et al. 2001), IC 348 (e.g., Cohen et near-IR supported the hypothesis that multiple types of al. 2003, Littlefair et al. 2005, Cieza & Baliber 2006), NGC variability are present among disk-bearing objects, includ- 2264 (e.g., Makidon et al. 2004, Lamm et al. 2004, Cieza ing accretion hot spots, circumstellar extinction changes, & Baliber 2006), σ Orionis (e.g., Scholz & Eislöffel 2004, and structural changes in the inner disk. Cody & Hillenbrand 2010), and Cepheus OB3 (Littlefair

12 3 The space photometry era one of two CoRoT “eyes”–its fields of view on the sky. The first CoRoT short run (“SRa01”) took place for 23 days straight in March 2008, returning hundreds of incredibly −0.2 SU Aur high quality (precision <5 millimagnitudes) light curves on both WTTSs and CTTSs. The results of this run are 0 reported in Alencar et al. (2010), Affer et al. (2013), and Fonseca et al. (2014). The Alencar et al. study revealed a 0.2 population of low-mass stars exhibiting periodic flux dips

Relative Magnitude similar to that seen in AA Tau by Bouvier et al. (2003). 0.4 0 5 10 15 20 25 Altogether, 30-40% of stars with inner dusty disks (as ob- Time(days) served with Spitzer) displayed AA Tau-like behavior. The variations were consistent with inner disk warps located Figure 2: Space-based light curve of SU Aurigae, as ob- near the corotation radius, with structural changes occur- served by the MOST telescope. While this object is best ing on timescales of a few rotation periods. This work was known for its deep flux dips, it instead displayed quasi- the first to show that the UX Ori phenomenon extended periodic behavior for much of this 2009-2010 campaign. to lower mass and shorter timescales; AA Tau periods oc- cupy the 3–10 day range. It also confirmed that there While ground-based monitoring of T Tauri stars has pro- are at least three distinct types of light curve morphology vided a wealth of information on the nature of their vari- among T Tauri stars: periodic spotted, AA Tau-like, and ations, such efforts have been hampered by sparse time “irregular” (aperiodic and stochastic). sampling and sometimes low photometric precision. With The second study on CoRoT SRa01 light curves of NGC the dawn of the twenty-first century came fantastic oppor- 2264 (Affer et al. 2013) focused on the sample of peri- tunities to employ space telescopes in the study of young odic stars, deriving rotation rates and comparing these star variability. Although not originally intended for the for WTTSs and CTTSs. Although rotation rates had monitoring of YSOs, the MOST (Microvariability and Os- been reported previously for NGC 2264 members (Lamm cillations of Stars; Walker et al. 2003) satellite launched in et al. 2004), these were subjected to aliasing in ground- 2003 provided some of the first high cadence (<1 minute), based datasets. CoRoT provided high accuracy periods high precision (few millimagnitudes), long time baseline for nearly 200 T Tauri stars, and this dataset was com- (several weeks) optical light curves of T Tauri and Her- bined with disk indicators from Spitzer and accretion in- big Ae/Be stars (Rucinski et al. 2008, 2010, Siwak et al. dicators from spectroscopy. The end result was that a 2011a,b, Cody & Hillenbrand 2013, Siwak et al. 2014). significant difference in rotation properties was detected These observations unveiled a rich variety of variability between accreting and non-accreting stars, thereby bol- behavior, from stochastic “red” noise and transient period- stering the disk locking theory (Affer et al. 2013). icities to sharp flux dips. For periodic objects, space-based monitoring revealed subtle changes in amplitude from cy- Ultimately, multiwavelength variability information is re- cle to cycle, as well as sudden shifts from one variability quired to fully unravel the origins of young star variabil- type to another (see Figure 2). In the case of the T Tauri ity; this was perhaps the one feature lacking in the CoRoT star SU Aurigae, periodic light curve behavior appeared at monitoring studies. YSOs and their disks are now known a timescale inconsistent with the rotation period predicted to vary at a wide range of wavelengths, from X-ray to mid- from the vsinii value, suggesting that interpretation of all infrared. With the onset of the Spitzer Space Telescope’s periodicities as starspots may need to be reconsidered. In Warm Mission, it became feasible to monitor young star addition to exploring accretion and disk-related variabil- clusters in the mid-infrared for up to 40 days at a time. Yet ity in young stars, MOST has been at the forefront of the until the first observations of IC 1396 (Morales-Calderón identification of δ Scuti pulsation in pre-main sequence et al. 2009) and IC 348 (Muzerolle et al. 2009) were ob- objects (e.g., Zwintz et al. 2013). tained, few attempts at mid-infrared monitoring had been made, and the results were not definitive (see Rebull 2011 The improved view of young stars provided by MOST for a summary). Spitzer observations immediately revealed was further enhanced by the CoRoT (COnvection, RO- ubiquitous brightness variations at the 10–50% level. Cap- tation and planetary Transits; Baglin et al. 2006) mis- italizing on this finding, the Young Stellar Object Vari- sion, launched in 2006. While MOST could only perform ability (YSOVAR) project acquired some 790 hours to ob- ∼ precision photometry on objects down to 12th magni- serve several thousand YSOs in 12 different star forming tude (thereby limiting the number of young star targets), regions (Rebull et al. 2014). With data in both the 3.6 and ∼ CoRoT’s limit of R 18 enabled the first space-based 4.5 µm bands of the Infrared Array Camera (IRAC), mul- monitoring of an entire young star cluster: NGC 2264. ticolor light curves were available for many of the targets. This ∼1–5 Myr region was the only one that fell within

13 As reported in Günther et al. (2014), Wolk et al. (2015), ciated with indicators of strong accretion, such as ultravi- and Poppenhaeger et al. (2015), the majority of YSOs dis- olet excess; it is investigated in Stauffer et al. (2014). The play reddening trends as they become fainter. However, bursters and dippers exhibit what we refer to as asym- a small number become bluer as they dim. Most of the metric flux behavior; these light curves appear different variability is consistent with reddening by dust extinction; when flipped upside-down. Another set of light curves alternatively, some of it may also be explained by struc- does not have this distinction; we call those with no de- tural rearrangements of the inner disk wall (e.g., Flaherty tectable periodicity “stochastic.” For light curves that do & Muzerolle 2010). Development of a light curve classifi- show periodicity but are not dippers because their fluxes cation scheme is currently underway (Rebull et al. 2015). are symmetric about the time axis, we have chosen the What is not clear is how the flux variations at very dif- label “quasi-periodic symmetric.” The term “periodic” is ferent wavelengths are connected. In 2011, we set out reserved for objects with the most stable periodicities; this to investigate this question by launching the Coordinated behavior is usually attributed to rotational modulation of Synoptic Investigation of NGC 2264 (CSI 2264; Cody et cool spots on the stellar surface. A schematic displaying al. 2013, 2014), a simultaneous effort with a dozen ground our classification system and the fractions of stars found and space-based telescopes in the X-ray, optical, near- in each category is shown in Figure 3. infrared, and mid-infrared. Starting in December 2011, the CSI 2264 campaign performed monitoring of several thousand YSOs in an approximately 1×1 degree field near the center of NGC 2264. The focus of the campaign were observations by the Warm Spitzer Space Telescope (Werner et al. 2004), in tandem with the CoRoT satellite. For much of December 2011, CoRoT and Spitzer were joined by the MOST telescope, along with the Chandra X- ray Observatory and 12 ground-based telescopes, including the Very Large Telescope and its FLAMES spectrograph. The unprecedented aspects of CSI 2264 are its high precision (1% or better for typical photometric points), high cadence (2 hours per IRAC datapoint and <10 minutes per CoRoT point), and long time baseline (30 days for Spitzer and 40 days for CoRoT). The combination of precision and time sampling has opened a new view of light curve morphologies, which is highlighted in the following. Figure 3: Schematic of different types of light curve mor- The exquisite data quality of the CSI 2264 campaign en- phologies found among young disk-bearing stars in the abled classification of light curves on a finer level than pre- NGC 2264 cluster, in the optical (“opt”) and infrared viously carried out. In Cody et al. (2014), we followed an (“IR”). Morphologies are categorized using two metrics: approach of visually examining and categorizing the light asymmetry (i.e., whether a light curve looks similar when curves, and subsequently confirming our decisions with flipped upside-down) and stochasticity (degree of period- statistics. A total of eight different morphologies emerged icity, or lack thereof). From Cody et al. (2014). from the set of optical and infrared light curves. Not surprisingly, one of the most prominent sets of morphologies Overall, we have evaluated a set of 162 disk-bearing YSO involves quasi-periodic fading events that become redder light curves with both CoRoT and Spitzer data. Exam- as they grow fainter. Though these are the same as the ples of these classes are shown in the optical in Figure 4, Alencar et al. (2010) AA Tau class, we refer to these as and in the infrared in Figure 5. Since the publication of “quasi-periodic dippers.” A similar morphology, which we these variability classes, one additional type of light curve call “aperiodic dippers,” involves fading events with no de- behavior has been identified in the CoRoT and Spitzer tectable periodicity. Also displaying fading behavior but dataset. These are narrow (<1 day), periodic flux dips in a strictly periodic manner are the eclipsing binaries of with variable depth. Stauffer et al. (2015) explore the na- NGC 2264. The most intriguing of these exhibits aperiodic ture of these flux dips, concluding that they are consistent out-of-eclipse variability indicative of a circumbinary disk with dust structures in or near the inner disk wall. (Gillen et al. 2014, 2015). While the dippers and eclipsing The CSI 2264 dataset has exposed just how diverse and binaries display fading, the opposite behavior appears in multifacted YSO variability can be. From the early classi- stars that we refer to as “bursters”– objects with frequent fications of periodic, irregular, and UX Ori stars, our mor- episodes of rapidly increasing flux. This behavior is asso- phological database has now expanded to include many

14 Figure 4: CoRoT space telescope data has recently enabled a high precision, high cadence view of T Tauri stars, revealing eight diﬀerent classes of optical variability, as depicted here (adapted from Cody et al. 2014).

10.60 12.20 Quasi-periodic dipper 10.65 12.25 10.70 12.30

[3.6] [3.6] 12.35 10.75 12.40 10.80 Burster 12.45 0 5 10 15 20 25 30 0 5 10 15 20 25 30 HJD-2455897 HJD-2455897

11.45 11.4 11.5 11.50 11.6 11.55 11.7 [3.6] 11.60 [3.6] 11.8 11.9 11.65 Aperiodic dipper Quasi-periodic symmetric 12.0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 HJD-2455897 HJD-2455897

10.0 11.2 Long timescale 11.3 10.2 11.4 10.4 [3.6] 11.5 [3.6] 10.6 11.6 Stochastic 0 5 10 15 20 25 30 0 5 10 15 20 25 30 HJD-2455897 HJD-2455897

11.94 11.6 Eclipsing binary 11.96 11.7 11.98

[3.6] [3.6] 11.8 12.00 12.02 Periodic 11.9 0 5 10 15 20 25 30 0 5 10 15 20 25 30 HJD-2455897 HJD-2455897

Figure 5: The diversity of infrared light curves from Spitzer infrared monitoring of the NGC 2264 cluster. Black circles are 3.6 µm datapoints, and grey circles are 4.5 µm points; the latter have had their mean shifted so as to overlap the 3.6 µm points. Similar to the optical behavior above, these time series show distinct morphological patterns that comprise eight diﬀerent categories. diﬀerent types of light curve behavior. How do these new changes in the luminosity, but also from changes in the observational insights build on our earlier knowledge of emission’s beaming, from changes in the extinction, and variability mechanisms? It is crucial to keep in mind that at infrared wavelengths also from changes in the arrange- astrophysical variability generally can come not just from ment of the reprocessing dust and gas. We now know that

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16 Abstracts of recently accepted papers

On the Stability of Extrasolar Planetary Systems and other Closely Orbiting Pairs Fred C. Adams1,2 and Anthony M. Bloch3 1 Physics Department, University of Michigan, Ann Arbor, MI 48109, USA 2 Astronomy Department, University of Michigan, Ann Arbor, MI 48109, USA 3 Mathematics Department, University of Michigan, Ann Arbor, MI 48109, USA E-mail contact: fca at umich.edu This paper considers the stability of tidal equilibria for planetary systems in which stellar rotation provides a significant contribution to the angular momentum budget. We begin by applying classic stability considerations for two bodies to planetary systems — where one mass is much smaller than the other. The application of these stability criteria to a subset of the Kepler sample indicates that the majority of the systems are not in a stable equilibrium state. Motivated by this finding, we generalize the stability calculation to include the quadrupole moment for the host star. In general, a stable equilibrium requires that the total system angular momentum exceeds a minimum value (denoted here as LX ) and that the orbital angular momentum of the planet exceeds a minimum fraction of the total. Most, but not all, of the observed planetary systems in the sample have enough total angular momentum to allow an equilibrium state. Even with the generalizations of this paper, however, most systems have too little orbital angular momentum (relative to the total) and are not in an equilibrium configuration. Finally, we consider the time evolution of these 6 7 planetary systems; the results constrain the tidal quality factor of the stars and suggest that 10 <∼ Q∗ <∼ 10 . Accepted by MNRAS http://arxiv.org/pdf/1411.2859

Evaporation of grain-surface species by shock waves in protoplanetary disk Takuhiro Aota1,2, Tsuyoshi Inoue3 and Yuri Aikawa1 1 Dept. of Earth and Planetary Sciences, Kobe University, Japan 2 Fuji Soft, Japan 3 National Astronomical Observatory of Japan E-mail contact: aikawa at kobe-u.ac.jp Recent ALMA (Atacama Large Millimeter/submillimeter Array) observations of young protostellar objects detected warm SO emission, which could be associated with a forming protostellar disk. In order to investigate if such warm gas can be produced by accretion shock onto the forming disk, we calculate the sputtering and thermal desorption of various grain surface species in one dimensional shock waves. We find that thermal desorption is much more efficient than the sputtering in the post-shock region. While H2O can be thermally desorbed, if the accretion velocity is larger −1 9 −3 than 8 km s with the pre-shock gas number density of 10 cm , SO is desorbed, if the accretion velocity ∼> 2 km −1 −1 9 −3 8 −3 s and ∼> 4km s , with the pre-shock density of 10 cm and 10 cm , respectively. We also find that the column 21 −2 density of hydrogen nuclei in warm post-shock gas is Nwarm ∼ 10 cm . Accepted by ApJ http://arxiv.org/pdf/1412.1178

Depletion of molecular gas by an accretion outburst in a protoplanetary disk A. Banzatti1, K. M. Pontoppidan1, S. Bruderer2, J. Muzerolle1 and M. R. Meyer3 1 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 2 Max-Planck-Institut f¨ur Extraterrestrische Physik, Giessenbachstr. 1, D-85748 Garching bei M¨unchen, Germany

17 3 ETH Zürich, Institut für Astronomie, Wolfgang-Pauli-Strasse 27, CH-8093 Zürich, Switzerland E-mail contact: banzatti at stsci.edu We investigate new and archival 3–5 µm high resolution (∼ 3kms−1) spectroscopy of molecular gas in the inner disk of the young solar-mass star EX Lupi, taken during and after the strong accretion outburst of 2008. The data were obtained using the CRIRES spectrometer at the ESO Very Large Telescope in 2008 and 2014. In 2008, emission lines from CO, H2O, and OH were detected with broad profiles tracing gas near and within the corotation radius (0.02–0.3 AU). In 2014, the spectra display marked differences. The CO lines, while still detected, are much weaker, and the H2O and OH lines have disappeared altogether. At 3 µm a veiled stellar photospheric spectrum is observed. Our analysis finds that the molecular gas mass in the inner disk has decreased by an order of magnitude since the outburst, matching a similar decrease in the accretion rate onto the star. We discuss these findings in the context of a rapid depletion of material accumulated beyond the disk corotation radius during quiescent periods, as proposed by models of episodic accretion in EXor type young stars. Accepted by ApJ Letters http://arxiv.org/pdf/1412.1824

The structure of protoplanetary discs around evolving young stars Bertram Bitsch1, Anders Johansen1, Michiel Lambrechts1, and Alessandro Morbidelli2 1 Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, 22100 Lund, Sweden 2 University Nice-Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur,Laboratoire LAGRANGE, CS 34229, 06304 NICE cedex 4, FRANCE E-mail contact: bert at astro.lu.se The formation of planets with gaseous envelopes takes place in protoplanetary accretion discs on time-scales of several millions of years. Small dust particles stick to each other to form pebbles, pebbles concentrate in the turbulent flow to form planetesimals and planetary embryos and grow to planets, which undergo substantial radial migration. All these processes are influenced by the underlying structure of the protoplanetary disc, specifically the profiles of temperature, gas scale height and density. The commonly used disc structure of the Minimum Mass Solar Nebular (MMSN) is a simple power law in all these quantities. However, protoplanetary disc models with both viscous and stellar heating show several bumps and dips in temperature, scale height and density caused by transitions in opacity, which are missing in the MMSN model. These play an important role in the formation of planets, as they can act as sweet spots for the formation of planetesimals via the streaming instability and affect the direction and magnitude of type- I-migration. We present 2D simulations of accretion discs that feature radiative cooling, viscous and stellar heating, and are linked to the observed evolutionary stages of protoplanetary discs and their host stars. These models allow us to identify preferred planetesimal and planet formation regions in the protoplanetary disc as a function of the disc’s metallicity, accretion rate and lifetime. We derive simple fitting formulae that feature all structural characteristics of protoplanetary discs during the evolution of several Myr. These fits are straightforward to apply for modelling any growth stage of planets where detailed knowledge of the underlying disc structure is required. Accepted by A&A http://arxiv.org/pdf/1411.3255

Reassessing the formation of the Inner Oort cloud in an embedded star cluster II: Probing the inner edge R. Brasser1,2 and M.E. Schwamb1 1 Institute for Astronomy and Astrophysics, Academia Sinica; 11F AS/NTU, National Taiwan University, 1 Roosevelt Rd., Sec. 4, Taipei 10617, Taiwan 2 Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan E-mail contact: brasser astro at yahoo.com The detached object Sedna is likely at the inner edge of the Oort cloud, more precisely the inner Oort cloud (IOC). Until recently it was the sole member of this population. The recent discovery of the detached object 2012 VP113

18 has confirmed that there should be more objects in this region. Three additional IOC candidates with orbits much closer to Neptune have been proposed in the past decade since Sedna’s discovery: 2000 CR105, 2004 VN112 and 2010 GB174. Sedna and 2012 VP113 have perhelia near 80 AU and semi-major axes over 250 AU. The latter three have perihelia between 44 AU and 50 AU and semi-major axes between 200 AU and 400 AU. Here we determine whether the latter three objects belong to the IOC or are from the Kuiper Belt’s Extended Scattered Disc (ESD) using numerical simulations. We assume that the IOC was formed when the Sun was in its birth cluster. We analyse the evolution of the IOC and the Scattered Disc (SD) during an episode of late giant planet migration. We examine the impact of giant planet migration in the context of four and five planets. We report that the detached objects 2004 VN112 and 2010 GB174 are likely members of the IOC that were placed there while the Sun was in its birth cluster or during an episode of Solar migration in the Galaxy. The origin of 2000 CR105 is ambiguous but it is likely it belongs to the ESD. Based on our simulations we find that the maximum perihelion distance of SD objects is 41 AU when the semi-major axis is higher than 250 AU. Objects closer in are subject to mean motion resonances with Neptune that may raise their perihelia. The five planet model yields the same outcome. We impose a conservative limit and state that all objects with perihelion distance q> 45 AU and semi-major axis a> 250 AU belong to the inner Oort cloud. Accepted by MNRAS http://arxiv.org/pdf/1411.1184

+ H2D observations give an age of at least one million years for a cloud core forming Sun-like stars Sandra Brünken1, Olli Sipilä2,3, Edward T. Chambers1, Jorma Harju2, Paola Caselli3,4, Oskar Asvany1, Cornelia E. Honingh1, Tomasz Kaminski5, Karl M. Menten5, Jürgen Stutzki1 and Stephan Schlemmer1 1 I. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, 50937 Köln, Germany 2 Department of Physics, PO Box 64, 00014 University of Helsinki, Finland 3 Max-Planck Institut für Extraterrestrische Physik, Giessenbachstrasse 1, 85741 Garching bei München, Germany 4 School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK 5 Max-Planck Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany E-mail contact: bruenken at ph1.uni-koeln.de The age of dense interstellar cloud cores, where stars and planets form, is a crucial parameter in star formation and difficult to measure. Some models predict rapid collapse (refs. 1, 2), whereas others predict timescales of more than one million years (ref. 3). One possible approach to determining the age is through chemical changes as cloud contraction occurs, in particular through indirect measurements of the ratio of the two spin isomers (ortho/para) of molecular hydrogen, H2, which decreases monotonically with age (refs.4-6). This has been done for the dense cloud core L183, + for which the deuterium fractionation of diazenylium (N2H ) was used as a chemical clock to infer (ref. 7) that the core has contracted rapidly (on a timescale of less than 700,000 years). Among astronomically observable molecules, + + the spin isomers of the deuterated trihydrogen cation, ortho-H2D and para-H2D , have the most direct chemical connections to H2 (refs. 8-12) and their abundance ratio provides a chemical clock that is sensitive to greater cloud + core ages. So far this ratio has not been determined because para-H2D is very difficult to observe. The detection of its rotational ground-state line has only now become possible thanks to accurate measurements of its transition frequency in the laboratory (ref. 13), and recent progress in instrumentation technology (refs. 14, 15). Here we report + observations of ortho- and para-H2D emission and absorption, respectively, from the dense cloud core hosting IRAS 16293-2422 A/B, a group of nascent solar-type stars (with ages of less than 100,000 years). Using the ortho/para ratio in conjunction with chemical models, we find that the dense core has been chemically processed for at least one + million years. The apparent discrepancy with the earlier N2H work (ref. 7) arises because that chemical clock turns + off sooner than the H2D clock, but both results imply that star-forming dense cores have ages of about one million years, rather than 100,000 years. Accepted by Nature http://dx.doi.org/10.1038/nature13924

19 Recovery of the Candidate Protoplanet HD 100546 b with Gemini/NICI and Detection of Additional (Planet-Induced?) Disk Structure at Small Separations Thayne Currie1, Takayuki Muto2, Tomoyuki Kudo1, Mitsuhiko Honda3, Timothy D. Brandt4, Carol Grady5, Misato Fukagawa6, Adam Burrows7, Markus Janson8, Masayuki Kuzuhara9, Michael W. McElwain10, Katherine Follette11, Jun Hashimoto12, Thomas Henning13, Ryo Kandori14, Nobuhiko Kusakabe14, Jungmi Kwon15, Kyle Mede15, Jun-ichi Morino14, Jun Nishikawa14, Tae-Soo Pyo1, Gene Serabyn16, Takuya Suenaga14, Yasuhiro Takahashi14,15, John Wisniewsk12, Motohide Tamura14,15 1 NAOJ, Subaru Telescope, 650 N Aohoku Pl., Hilo, HI 96720, USA 2 Kogashin University, Japan 3 Kanagawa University, Japan 4 Astrophysics Department, Institute for Advanced Study, Princeton, NJ, USA 5 Eureka Scientific, 2452 Delmer, Suite 100, Oakland CA96002, USA 6 Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan 7 Department of Astrophysical Sciences, Princeton University, 7 Ivy Lane, Princeton, NJ, USA 8 Stockholm University, Sweden 9 Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan 10 Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771, USA 11 Department of Astronomy, Steward Observatory, University of Arizona 12 H. L. Dodge Department of Physics & Astronomy, University of Oklahoma, 440 W Brooks St Norman, OK 73019, USA 13 Max Planck Institute for Astronomy, Konigstuhl 17, 69117 Heidelberg, Germany 14 National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo, 181-8588, Japan 15 Department of Astronomy, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan 16 Jet Propulsion Laboratory, 4800 Oak Grove Drive, MS 183-900, Pasadena, CA 91109, USA E-mail contact: currie at naoj.org We report the first independent, second-epoch (re-)detection of a directly-imaged protoplanet candidate. Using L′ high-contrast imaging of HD 100546 taken with the Near-Infrared Coronagraph and Imager (NICI) on Gemini South, we recover ‘HD 100546 b’ with a position and brightness consistent with the original VLT/NaCo detection from Quanz et al, although data obtained after 2013 will be required to decisively demonstrate common proper motion. HD 100546 b may be spatially resolved, up to ≈ 12–13 AU in diameter, and is embedded in a finger of thermal IR bright, polarized ′′ emission extending inwards to at least 0. 3. Standard hot-start models imply a mass of ≈ 15 MJ. But if HD 100546 b is newly formed or made visible by a circumplanetary disk, both of which are plausible, its mass is significantly lower (e.g. 1–7 MJ). Additionally, we discover a thermal IR-bright disk feature, possibly a spiral density wave, at roughly the same angular separation as HD 100546 b but 90 degrees away. Our interpretation of this feature as a spiral arm is not decisive, but modeling analyses using spiral density wave theory implies a wave launching point exterior to ≈ 0′′. 45 embedded within the visible disk structure: plausibly evidence for a second, hitherto unseen wide-separation planet. With one confirmed protoplanet candidate and evidence for 1–2 others, HD 100546 is an important evolutionary precursor to intermediate-mass stars with multiple super-jovian planets at moderate/wide separations like HR 8799. Accepted by ApJL http://arxiv.org/pdf/1411.0315

Sub-stellar Companions and Stellar Multiplicity in the Taurus Star-Forming Region Sebastian Daemgen1, Mariangela Bonavita2, Ray Jayawardhana3 , David Lafrenière4 and Markus Janson5 1 Dept. of Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON, Canada M5H 3H4 2 The University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, U.K. 3 Physics & Astronomy, York University, Toronto, Ontario L3T 3R1, Canada 4 Department of Physics, University of Montréal, Montréal, QC, Canada 5 Department of Astronomy, Stockholm University, Stockholm, Sweden E-mail contact: daemgen at astro.utoronto.ca

20 We present results from a large, high-spatial-resolution near-infrared imaging search for stellar and sub-stellar companions in the Taurus-Auriga star-forming region. The sample covers 64 stars with masses between those of the most massive Taurus members at ∼3 M⊙ and low-mass stars at ∼0.2 M⊙. We detected 74 companion candidates, 34 of these reported for the first time. Twenty-five companions are likely physically bound, partly confirmed by follow-up observations. Four candidate companions are likely unrelated field stars. Assuming physical association with their host star, estimated companion masses are as low as ∼2 MJup. The inferred multiplicity frequency within our sensitivity +6.6 limits between ∼10–1500AU is 26.3−4.9%. Applying a completeness correction, 62%±14% of all Taurus stars between +4.2 0.7 and 1.4 M⊙ appear to be multiple. Higher order multiples were found in 1.8−1.5% of the cases, in agreement with previous observations of the field. We estimate a sub-stellar companion frequency of ∼3.5–8.8% within our sensitivity limits from the discovery of two likely bound and three other tentative very low-mass companions. This frequency appears to be in agreement with what is expected from the tail of the stellar companion mass ratio distribution, suggesting that stellar and brown dwarf companions share the same dominant formation mechanism. Further, we find evidence for possible evolution of binary parameters between two identified sub-populations in Taurus with ages of ∼2 Myr and ∼20 Myr, respectively. Accepted by the Astrophysical Journal http://arxiv.org/pdf/1411.7031

Testing Magnetic Field Models for the Class 0 Protostar L1527 J.A. Davidson1, Z-Y. Li2, C.L.H. Hull3,12, R.L. Plambeck3, W. Kwon4, R.M. Crutcher5, and L.W. Looney5, G. Novak6, N.L. Chapman6, B.C. Matthews7,8, I.W. Stephens9, J.J. Tobin10, and T.J. Jones11 1 University of Western Australia, School of Physics, 35 Stirling Hwy, Crawley, WA 6009, Australia 2 University of Virginia, Astronomy Department, Charlottesville, VA 22904, USA 3 University of California, Astronomy Department & Radio Astronomy Laboratory, Berkeley, CA 94720-3411, USA 4 SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD, Groningen, The Netherlands 5 University of Illinois, Department of Astronomy, 1002 West Green St, Urbana, IL 61801, USA 6 Northwestern University, Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and the Department of Physics & Astronomy, 2145 Sheridan Road, Evanston, IL 60208, USA 7 Herzberg Astronomy & Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC, V9E 2E7, Canada 8 University of Victoria, Department of Physics & Astronomy, 3800 Finnerty Road, Victoria, BC, V8P 1A1, Canada 9 Boston University, Institute for Astrophysical Research, Boston, MA 02215, USA 10 National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA 11 University of Minnesota, 116 Church St S.E., Minneapolis, MN, 55455 USA 12 Harvard-Smithsonian Center for Astrophysics, 60 Garden St, MS 42, Cambridge, MA 02138, USA E-mail contact: jackie.davidson at uwa.edu.au For the Class 0 protostar, L1527, we compare 131 polarization vectors from SCUPOL/JCMT, SHARP/CSO and TADPOL/CARMA observations with the corresponding model polarization vectors of four ideal-MHD, non-turbulent, cloud core collapse models. These four models differ by their initial magnetic fields before collapse; two initially have aligned fields (strong and weak) and two initially have orthogonal fields (strong and weak) with respect to the rotation axis of the L1527 core. Only the initial weak orthogonal field model produces the observed circumstellar disk within L1527. This is a characteristic of nearly all ideal-MHD, non-turbulent, core collapse models. In this paper we test whether this weak orthogonal model also has the best agreement between its magnetic field structure and that inferred from the polarimetry observations of L1527. We found that this is not the case; based on the polarimetry observations the most favored model of the four is the weak aligned model. However, this model does not produce a circumstellar disk, so our result implies that a non-turbulent, ideal-MHD global collapse model probably does not represent the core collapse that has occurred in L1527. Our study also illustrates the importance of using polarization vectors covering a large area of a cloud core to determine the initial magnetic field orientation before collapse; the inner core magnetic field structure can be highly altered by a collapse and so measurements from this region alone can give unreliable estimates of the initial field configuration before collapse. Accepted by ApJ http://arxiv.org/pdf/1411.4913

21 A Young GMC Formed at the Interface of Two Colliding Supershells: Observations Meet Simulations J.R. Dawson1,2, E. Ntormousi3, Y. Fukui4, T. Hayakawa4 , and K. Fierlinger5,6 1 Department of Physics and Astronomy and MQ Research Centre in Astronomy, Astrophysics and Astrophotonics, Macquarie University, NSW 2109, Australia 2 Australia Telescope National Facility, CSIRO Astronomy and Space Science, PO Box 76, Epping, NSW 1710, Australia 3 Service dAstrophysique, CEA/DSM/IRFU Orme des Merisiers, Bat 709 Gif-sur-Yvette, 91191 France 4 Department of Physics and Astrophysics, Nagoya University, Chikusa-ku, Nagoya, Japan 5 University Observatory Munich, Scheinerstr. 1, D-81679 München, Germany 6 Excellence Cluster Universe, Technische Universität München, Boltzmannstr. 2, D-85748, Garching, Germany E-mail contact: joanne.dawson at mq.edu.au Dense, star-forming gas is believed to form at the stagnation points of large-scale ISM flows, but observational examples of this process in action are rare. We here present a giant molecular cloud (GMC) sandwiched between two colliding Milky Way supershells, which we argue shows strong evidence of having formed from material accumulated at the collision zone. Combining 12CO, 13CO and C18O (J = 1–0) data with new high-resolution, 3D hydrodynamical simulations of colliding supershells, we discuss the origin and nature of the GMC (G288.5+1.5), favoring a scenario in which the cloud was partially seeded by pre-existing denser material, but assembled into its current form by the action of the shells. This assembly includes the production of some new molecular gas. The GMC is well interpreted as 5 non-self-gravitating, despite its high mass (MH2 ∼ 1.7×10 M⊙), and is likely pressure confined by the colliding flows, implying that self-gravity was not a necessary ingredient for its formation. Much of the molecular gas is relatively diffuse, and the cloud as a whole shows little evidence of star formation activity, supporting a scenario in which it is young and recently formed. Drip-like formations along its lower edge may be explained by fluid dynamical instabilities in the cooled gas. Accepted by ApJ http://arxiv.org/pdf/1411.2708

The frequency and nature of cloud-cloud collisions in galaxies C. L. Dobbs1, J. E. Pringle2 and A. Duarte-Cabral1 1 School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK 2 Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK E-mail contact: dobbs at astro.ex.ac.uk We investigate cloud–cloud collisions, and GMC evolution, in hydrodynamic simulations of isolated galaxies. The simulations include heating and cooling of the ISM, self–gravity and stellar feedback. Over timescales less than 5 Myr most clouds undergo no change, and mergers and splits are found to be typically two body processes, but evolution over longer timescales is more complex and involves a greater fraction of intercloud material. We find that mergers, or collisions, occur every 8-10 Myr (1/15th of an orbit) in a simulation with spiral arms, and once every 28 Myr (1/5th of an orbit) with no imposed spiral arms. Both figures are higher than expected from analytic estimates, as clouds are not uniformly distributed in the galaxy. Thus clouds can be expected to undergo between zero and a few collisions over their lifetime. We present specific examples of cloud–10 Myr (1/15th of an orbit) in a simulation with spiral arms, and once every 28 Myr (1/5th of an orbit) with no imposed spiral arms. Both figures are higher than expected from analytic estimates, as clouds are not uniformly distributed in the galaxy. Thus clouds can be expected to undergo between zero and a few collisions over their lifetime. We present specific examples of cloud–cloud interactions often better resemble a smaller cloud nudging a larger cloud. Our findings are consistent with the view that spiral arms make little difference to overall star formation rates in galaxies, and we see no evidence that collisions likely produce massive clusters. However, to confirm the outcome of such massive cloud collisions we ideally need higher resolution simulations. Accepted by MNRAS http://arxiv.org/pdf/1411.0840

22 The JCMT Gould Belt Survey: low-mass proto-planetary discs from a SCUBA-2 census of NGC1333 Peter Dodds1, Jane Greaves1, Aleks Scholz1, Jennifer Hatchell2 and Wayne Holland3 1 SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK 2 Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK 3 UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK E-mail contact: as110 at st-andrews.ac.uk NGC 1333 is a 1-2 Myr old cluster of stars in the Perseus molecular cloud. We used 850 µm data from the Gould Belt Survey with SCUBA-2 on the JCMT to measure or place limits on disc masses for 82 Class II sources in this cluster. Eight disc-candidates were detected; one is estimated to have mass of about 9 MJupiter in dust plus gas, while the others host only 2-4 MJupiter of circumstellar material. None of these discs exceeds the threshold for the ’Minimum Mass Solar Nebula’ (MMSN). This reinforces previous claims that only a small fraction of Class II sources at an age of 1-2Myr has discs exceeding the MMSN threshold and thus can form a planetary system like our own. However, other regions with similarly low fractions of MMSN discs (IC348, UpSco, σ Ori) are thought to be older than NGC 1333. Compared with coeval regions, the exceptionally low fraction of massive discs in NGC 1333 cannot easily be explained by the effects of UV radiation or stellar encounters. Our results indicate that additional environmental factors significantly affect disc evolution and the outcome of planet formation by core accretion. Accepted by MNRAS http://arxiv.org/pdf/1411.5931

Time-monitoring Observations of Brγ Emission from Young Stars J.A. Eisner1,2, G.H. Rieke1, M.J. Rieke1, K.M. Flaherty1,4, Jordan M. Stone1, T.J. Arnold1, S.R. Cortes1, E. Cox1, C. Hawkins2, A. Cole, S. Zajac2, A.L. Rudolph2 1 Steward Observatory, The University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721, USA 2 Department of Physics and Astronomy, California State Polytechnic University, 3801 W Temple Ave, Pomona, CA 91768, USA 3 Visiting Fellow, JILA, University of Colorado and NIST, Boulder, CO 80309 4 Current address: Astronomy Department, Wesleyan University, Middletown, CT 06459, USA E-mail contact: jeisner at email.arizona.edu We present multiple epochs of near-IR spectroscopy for a sample of 25 young stars, including T Tauri, Herbig Ae/Be, and FU Ori objects. Using the FSPEC instrument on the Bok 90-inch telescope, we obtained K-band spectra of the Brγ transition of hydrogen, with a resolution of ∼3500. Epochs were taken over a span of >1 year, sampling time- spacings of roughly one day, one month, and one year. The majority of our targets show Brγ emission, and in some cases these are the ﬁrst published detections. Time-variability is seen in approximately half of the targets showing Brγ emission. We compare the observed variability with expectations for rotationally-modulated accretion onto the central stars and time-variable continuum emission or extinction from matter in the inner disk. Our observations are not entirely consistent with models of rotationally-modulated magnetospheric accretion. Further monitoring, over a larger number of epochs, will facilitate more quantitative constraints on variability timescales and amplitudes, and a more conclusive comparison with theoretical models. Accepted by MNRAS http://arxiv.org/pdf/1411.5370

Vortex cycles at the inner edges of dead zones in protoplanetary disks Julien Faure1, S´ebastien Fromang1, Henrik Latter2 and Heloise Meheut1 1 Laboratoire AIM, CEA/DSM–CNRS–Universit´eParis 7, IRFU/Service d’Astrophysique, CEA-Saclay, 91191 Gif- sur-Yvette, France 2 Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, UK

23 E-mail contact: julien.faure at cea.fr In protoplanetary disks, the inner boundary between the turbulent and laminar regions is a promising site for planet formation because solids may become trapped at the interface itself or in vortices generated by the Rossby wave instability. The disk thermodynamics and the turbulent dynamics at that location are entwined because of the importance of turbulent dissipation on thermal ionization and, conversely, of thermal ionisation on the turbulence. However, most previous work has neglected this dynamical coupling and have thus missed a key element of the physics in this region. In this paper, we aim to determine how the the interplay between ionization and turbulence impacts on the formation and evolution of vortices at the interface between the active and the dead zones. Using the Godunov code RAMSES, we have performed a 3D magnetohydrodynamic global numerical simulation of a cylindrical model of an MRI–turbulent protoplanetary disk, including thermodynamical effects as well as a temperature-dependant resistivity. The comparison with an analogous 2D viscous simulation has been extensively used to help identify the relevant physical processes and the disk’s long-term evolution. We find that a vortex formed at the interface, due to Rossby wave instability, migrates inward and penetrates the active zone where it is destroyed by turbulent motions. Subsequently, a new vortex emerges a few tens of orbits later at the interface, and the new vortex migrates inward too. The sequence repeats itself, resulting in cycles of vortex formation, migration, and disruption. This surprising behavior is successfully reproduced using two different codes. In this paper, we characterize this vortex life cycle and discuss its implications for planet formation at the dead/active interface. Our results also call for a better understanding of vortex migration in complex thermodynamical environments. Our simulations highlight the importance of thermodynamical processes for the vortex evolution at the dead zone inner edge. Accepted by Astronomy and Astrophysics http://arxiv.org/pdf/1411.3236

The Turbulent Dynamo in Highly Compressible Supersonic Plasmas Christoph Federrath1, Jennifer Schober2, Stefano Bovino3 and Dominik R. G. Schleicher3 1 Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611, Australia 2 Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg, Germany 3 Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany E-mail contact: christoph.federrath at anu.edu.au The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early Universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohy- drodynamical simulations of supersonic turbulence with grid resolutions of up to 10243 cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ν/η =0.1–10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ≥ 1 in supersonic turbulence. We +43 measure the critical magnetic Reynolds number, Rmcrit = 129−31, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early Universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars. Accepted by The Astrophyiscal Journal Letters http://arxiv.org/pdf/1411.4707

Gaps, Rings, and Non-Axisymmetric Structures in Protoplanetary Disks - From Simu- lations to ALMA Observations M. Flock1, J.P. Ruge2, N. Dzyurkevich3, Th. Henning4, H. Klahr4 and S. Wolf2 1 CEA UMR AIM Irfu, SAP, CEA-CNRS-Univ. Paris Diderot, Centre de Saclay, 91191 Gif-sur-Yvette, France 2 Universit¨at zu Kiel, Institut fr Theoretische Physik und Astrophysik, Leibnitzstr. 15, 24098 Kiel, Germany

24 3 Laboratoire de radioastronomie, UMR 8112 du CNRS, Ecole´ normale supérieure et Observatoire de Paris, 24 rue Lhomond, F- 75231 Paris Cedex 05, France 4 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany E-mail contact: mario.flock at cea.fr Recent observations by the Atacama Large Millimeter/submillimeter Array (ALMA) of disks around young stars revealed distinct asymmetries in the dust continuum emission. In this work we want to study axisymmetric and non-axisymmetric structures, evocated by the magneto-rotational instability in the outer regions of protoplanetary disks. We combine the results of state-of-the-art numerical simulations with post-processing radiative transfer (RT) to generate synthetic maps and predictions for ALMA. We performed non-ideal global 3D MHD stratified simulations of the dead-zone outer edge using the FARGO MHD code PLUTO. The stellar and disk parameters are taken from a parameterized disk model applied for fitting high-angular resolution multi-wavelength observations of circumstellar disks. The 2D temperature and density profiles are calculated consistently from a given surface density profile and Monte-Carlo radiative transfer. The 2D Ohmic resistivity profile is calculated using a dust chemistry model. The magnetic field is a vertical net flux field. The resulting dust reemission provides the basis for the simulation of observations with ALMA. The fiducial model develops a large gap followed by a jump in surface density located at the dead-zone outer edge. The jump in density and pressure is strong enough to stop the radial drift of particles. In addition, we observe the generation of vortices by the Rossby wave instability (RWI) at the jumps location close to 60 AU. The vortices are steadily generated and destroyed at a cycle of 40 local orbits which corresponds to a lifetime of over 19000 years at this location. The RT results and simulated ALMA observations predict the feasibility to observe such large scale structures appearing in magnetized disks without having a planet. Accepted by A&A http://arxiv.org/pdf/1411.2736

IN-SYNC II: Virial Stars from Sub-Virial Cores – The Velocity Dispersion of Embedded Pre-Main-Sequence Stars in NGC 1333 Jonathan B. Foster1, Michiel Cottaar2, Kevin R. Covey3,4, Héctor G. Arce5, Michael R. Meyer2, David L. Nidever6, Keivan G. Stassun7,8, Jonathan C. Tan9, S. Drew Chojnowski10, Nicola da Rio9, Kevin M. Flaherty11, Luisa Rebull12, Peter M. Frinchaboy13, Steven R. Majewski10, Michael Skrutskie10 and John C. Wilson10 1 Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06520, USA 2 Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland 3 Lowell Observatory, Flagstaff, AZ 86001, USA 4 Current Address: Dept. of Physics & Astronomy, Western Washington Univ., 516 High Street, Bellingham WA 98225, USA 5 Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520, USA 6 Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA 7 Department of Physics & Astronomy, Vanderbilt University, VU Station B 1807, Nashville, TN, USA 8 Physics Department, Fisk University, Nashville, TN 37208, USA 9 Department of Astronomy, University of Florida, Gainesville, FL 32611, USA 10 Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA 11 Astronomy Department, Wesleyan University, Middletown, CT, 06459, USA 12 Spitzer Science Center/Caltech, 1200 E. California Blvd., Pasadena, CA 91125, USA 13 Department of Physics & Astronomy, Texas Christian University, Fort Worth, TX 76129, USA 14 Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA E-mail contact: jonathan.b.foster at yale.edu The initial velocity dispersion of newborn stars is a major unconstrained aspect of star formation theory. Using near-infrared spectra obtained with the APOGEE spectrograph, we show that the velocity dispersion of young (1-2 Myr) stars in NGC 1333 is 0.92±0.12 km s−1 after correcting for measurement uncertainties and the effect of binaries. This velocity dispersion is consistent with the virial velocity of the region and the diffuse gas velocity dispersion, but significantly larger than the velocity dispersion of the dense, star-forming cores, which have a sub-virial velocity dispersion of 0.5 km−1. Since the NGC 1333 cluster is dynamically young and deeply embedded, this measurement

25 provides a strong constraint on the initial velocity dispersion of newly-formed stars. We propose that the difference in velocity dispersion between stars and dense cores may be due to the influence of a 70µG magnetic field acting on the dense cores, or be the signature of a cluster with initial sub-structure undergoing global collapse. Accepted by ApJ http://arxiv.org/pdf/1411.6013

Dense Molecular Clumps associated with the LMC Supergiant Shells LMC 4 and LMC 5 Kosuke Fujii1,2, Tetsuhiro Minamidani3, Norikazu Mizuno1,2, Toshikazu Onishi4, Akiko Kawamura2, Erik Muller2, Joanne Dawson5,6, Kenichi Tatematsu2, Tetsuo Hasegawa2, Tomoka Tosaki7, Rie E. Miura2, Kazuyuki Muraoka4, Takeshi Sakai8, Takashi Tsukagoshi9, Kunihiko Tanaka10, Hajime Ezawa2 and Yasuo Fukui11 1 Department of Astronomy, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 133-0033, Japan; 2 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 3 Nobeyama Radio Observatory, 462-2 Nobeyama Minamimaki-mura, Minamisaku-gun, Nagano 384-1305, Japan 4 Department of Physical Science, Osaka Prefecture University, Gakuen 1-1, Sakai, Osaka 599-8531, Japan 5 Australia Telescope National Facility, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710, Australia 6 Department of Physics and Astronomy and MQ Research Centre in Astronomy, Astrophysics and Astrophotonics, Macquarie University, NSW 2109, Australia 7 Joetsu University of Education, Yamayashiki-machi, Joetsu, Niigata 943-8512, Japan 8 Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182- 8585, Japan 9 College of Science, Ibaraki University, Bunkyo 2-1-1, Mito 310-8512, Japan 10 Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, Kanagawa 223-8522, Japan 11 Department of Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan E-mail contact: kosuke.fujii at nao.ac.jp We investigate the eﬀects of Supergiant Shells (SGSs) and their interaction on dense molecular clumps by observing the Large Magellanic Cloud (LMC) star-forming regions N48 and N49, which are located between two SGSs, LMC 4 and LMC 5. 12CO (J=3–2, 1–0) and 13CO(J=1–0) observations with the ASTE and Mopra telescopes have been carried out towards these regions. A clumpy distribution of dense molecular clumps is revealed with 7 pc spatial resolution. Large velocity gradient analysis shows that the molecular hydrogen densities (n(H2)) of the clumps are 3 5 −3 distributed from low to high density (10 –10 cm ) and their kinetic temperatures (Tkin) are typically high (greater than 50 K). These clumps seem to be in the early stages of star formation, as also indicated from the distribution of Hα, young stellar object candidates, and IR emission. We found that the N48 region is located in the high column density H I envelope at the interface of the two SGSs and the star formation is relatively evolved, whereas the N49 region is associated with LMC 5 alone and the star formation is quiet. The clumps in the N48 region typically show high n(H2) and Tkin, which are as dense and warm as the clumps in LMC massive cluster-forming areas (30 Dor, N159). These results suggest that the large-scale structure of the SGSs, especially the interaction of two SGSs, works eﬃciently on the formation of dense molecular clumps and stars. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1411.0097

G305.136+0.068: A massive and dense cold core in an early stage of evolution Guido Garay,1 Diego Mardones,1 Yanett Contreras,1,2 Jaime E. Pineda,3 Elise Servajean,1 and Andr´es E. Guzm´an.1,4 1Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile

26 2CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710, Australia 3Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland 4Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, USA E-mail contact: guido at das.uchile.cl We report molecular line observations, made with ASTE and SEST, and dust continuum observations at 0.87 mm, made with APEX, towards the cold dust core G305.136+0.068. The molecular observations show that the core is 3 isolated and roughly circularly symmetric and imply that it has a mass of 1.1 × 10 M⊙. A simultaneous model fitting of the spectra observed in four transitions of CS, using a non-LTE radiative transfer code, indicates that the core is centrally condensed, with the density decreasing with radius as r−1.8, and that the turbulent velocity increases towards the center. The dust observations also indicate that the core is highly centrally condensed and that the average column density is 1.1 g cm−2, value slightly above the theoretical threshold required for the formation of high mass stars. A fit to the spectral energy distribution of the emission from the core indicates a dust temperature of 17 ± 2 K, confirming that the core is cold. Spitzer images show that the core is seen in silhouette from 3.6 to 24.0 µm and that is surrounded by an envelope of emission, presumably tracing an externally excited photo-dissociated region. We found two embedded sources within a region of 20 arcsec centered at the peak of the core, one of which is young, −4 −1 has a luminosity of 66 L⊙ and is accreting mass with a high accretion rate, of ∼ 1 × 10 M⊙ yr . We suggest that this object corresponds to the seed of a high mass protostar still in the process of formation. The present observations support the hypothesis that G305.136+0.068 is a massive and dense cold core in an early stage of evolution, in which the formation of a high mass star has just started. Accepted by ApJ http://arxiv.org/pdf/1411.5637

IRAS 16547−4247: A New Candidate of a Protocluster Unveiled with ALMA Aya E. Higuchi1, Kazuya Saigo2, James O. Chibueze2,3, Patricio Sanhueza2, Shigehisa Takakuwa4 and Guido Garay5 1 Ibaraki University, College of Science, 2-1-1 Bunkyo, Mito, 310-8512, Japan 2 National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan 3 Department of Physics and Astronomy, Faculty of Physical Sciences, University of Nigeria, Carver Building, 1 University Road, Nsukka, Nigeria 4 Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan 5 Departamento de Astronomia, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile E-mail contact: ahiguchi at mx.ibaraki.ac.jp 12 We present the results of continuum and CO(3–2) and CH3OH(7–6) line observations of IRAS 16547−4247 made with the Atacama Large Millimeter/submillimeter Array (ALMA) at an angular resolution of 0.5 arcsec. The 12CO(3– 2) emission shows two high-velocity outflows whose driving sources are located within the dust continuum peak. The alignment of these outflows do not coincide with that of the wide-angle, large scale, bipolar outflow detected with APEX in previous studies. The CH3OH(7–6) line emission traces an hourglass structure associated with the cavity walls created by the outflow lobes.Taking into account our results together with the position of the H2O and class I CH3OH maser clusters, we discuss two possible scenarios that can explain the hourglass structure observed in IRAS 16547−4247: (1) precession of a biconical jet, (2) multiple, or at least two, driving sources powering intersecting outflows. Combining the available evidence, namely, the presence of two cross-aligned bipolar outflows and two different H2O maser groups, we suggest that IRAS 16547−4247 represents an early formation phase of a protocluster. Accepted by ApJL http://arxiv.org/abs/1411.7485

A new and simple approach to determine the abundance of hydrogen molecules on interstellar ice mantles Ugo Hincelin1, Qiang Chang2,3 and Eric Herbst1 1 Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA

27 2 XinJiang Astronomical Observatory, Chinese Academy of Sciences, 150 Science 1-Street, Urumqi 830011, PR China 3 Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008, PR China E-mail contact: ugo.hincelin at virginia.edu Water is usually the main component of ice mantles, which cover the cores of dust grains in cold portions of dense interstellar clouds. When molecular hydrogen is adsorbed onto an icy mantle through physisorption, a common assumption in gas-grain rate-equation models is to use an adsorption energy for molecular hydrogen on a pure water substrate. However, at high density and low temperature, when H2 is efficiently adsorbed onto the mantle, its surface abundance can be strongly overestimated if this assumption is still used. Unfortunately, the more detailed microscopic Monte Carlo treatment cannot be used to study the abundance of H2 in ice mantles if a full gas-grain network is utilized. We present a numerical method adapted for rate-equation models that takes into account the possibility that an H2 molecule can, while diffusing on the surface, find itself bound to another hydrogen molecule, with a far weaker bond than the H2-water bond, which can lead to more efficient desorption. We label the ensuing desorption ”encounter desorption”. The method is implemented first in a simple system consisting only of hydrogen molecules at steady state between gas and dust using the rate-equation approach and comparing the results with the results of a microscopic Monte Carlo calculation. We then discuss the use of the rate-equation approach with encounter desorption embedded in a complete gas-grain chemical network. For the simple system, the rate-equation model with encounter desorption reproduces the H2 granular coverage com- puted by the microscopic Monte Carlo model at 10 K for a gas density from 104 to 1012 cm−3, and yields up to a factor 12 −3 4 difference above 10 cm . The H2 granular coverage is also reproduced by a complete gas-grain network. We use the rate-equation approach to study the gas-grain chemistry of cold dense regions with and without the encounter desorption mechanism. We find that the grain surface and gas phase species can be sensitive to the H2 coverage, up to several orders of magnitude, depending on the species, the density, and the time considered. The method is especially useful for dense and cold environments, and for time-dependent physical conditions, such as occur in the collapse of dense cores and the formation of protoplanetary disks. It is not significantly CPU time consuming, so can be used for example with complex 3D chemical-hydrodynamical simulations. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1410.7375v2.pdf

Reddening, Distance, and Stellar Content of the Young Open Cluster Westerlund 2 Hyeonoh Hur1, Byeong-Gon Park2, Hwankyung Sung1, Michael S. Bessell3, Beomdu Lim1,2, Moo- Young Chun2, Sangmo Tony Sohn4 1 Department of Astronomy and Space Science, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747, Korea 2 Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 305-348, Korea 3 Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek ACT 2611, Australia 4 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 E-mail contact: sungh at sejong.ac.kr

We present deep UBVIC photometric data of the young open cluster Westerlund 2. An abnormal reddening law of RV,cl = 4.14 ± 0.08 was found for the highly reddened early-type members (E(B − V ) ≥ 1.45), whereas a fairly normal reddening law of RV,fg =3.33 ± 0.03 was confirmed for the foreground early-type stars (E(B − V )fg < 1.05). The distance modulus was determined from zero-age main-sequence (ZAMS) fitting to the reddening-corrected colour- +0.4 magnitude diagram of the early-type members to be V0 − MV = 13.9 ± 0.14 (random error) −0.1 (the upper limit of +1.2 systematic error) mag (d = 6.0 ± 0.4−0.3 kpc). To obtain the initial mass function, pre-main-sequence (PMS) stars were selected by identifying the optical counterparts of Chandra X-ray sources and mid-infrared emission stars from the Spitzer GLIMPSE source catalog. The initial mass function shows a shallow slope of Γ = −1.1 ± 0.1 down to log m =0.7. The total mass of Westerlund 2 is estimated to be at least 7,400 M⊙. The age of Westerlund 2 from the main-sequence turn-on and PMS stars is estimated to be ∼< 1.5 Myr. We confirmed the existence of a clump of PMS stars located ∼1′ north of the core of Westerlund 2, but we could not find any clear evidence for an age difference

28 between the core and the northern clump. Accepted by MNRAS http://arxiv.org/pdf/1411.0879

Depletion of chlorine into HCl ice in a protostellar core M. Kama1, E. Caux2,3, A. López-Sepulcre4,5, V. Wakelam6,7, C. Dominik8,9, C. Ceccarelli4,5, M. Lanza10, F. Lique10, B.B. Ochsendorf1, D.C. Lis11,12,13, R.N. Caballero14 and A.G.G.M. Tielens1 1 Leiden Observatory, P.O. Box 9513, NL-2300 RA, Leiden, The Netherlands 2 Universitéde Toulouse, UPS-OMP, IRAP, Toulouse, France 3 CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France 4 Universitéde Grenoble Alpes, IPAG, F-38000 Grenoble, France 5 CNRS, IPAG, F-38000 Grenoble, France 6 Univ. Bordeaux, LAB, UMR 5804, F-33270, Floirac, France 7 CNRS, LAB, UMR 5804, F-33270, Floirac, France 8 Astronomical Institute Anton Pannekoek, Science Park 904, NL-1098 XH Amsterdam, The Netherlands 9 Department of Astrophysics/IMAPP, Radboud University Nijmegen, Nijmegen, The Netherlands 10 LOMC - UMR 6294, CNRS-Universitédu Havre, 25 rue Philippe Lebon, BP 1123 - 76 063 Le Havre cedex, France 11 LERMA, Observatoire de Paris, PSL Research University, CNRS, UMR 8112, F-75014, Paris, France 12 Sorbonne Universités, UniversitéPierre et Marie Curie, Paris 6, CNRS, Observatoire de Paris, UMR 8112, LERMA, Paris, France 13 California Institute of Technology, Cahill Center for Astronomy and Astrophysics 301-17, Pasadena, CA 91125, USA 14 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany E-mail contact: mkama at strw.leidenuniv.nl The freezeout of gas-phase species onto cold dust grains can drastically alter the chemistry and the heating-cooling balance of protostellar material. In contrast to well-known species such as carbon monoxide (CO), the freezeout of various carriers of elements with abundances < 10−5 has not yet been well studied. Our aim here is to study the + depletion of chlorine in the protostellar core, OMC-2 FIR 4. We observed transitions of HCl and H2Cl towards OMC-2 FIR 4 using the Herschel Space Observatory and Caltech Submillimeter Observatory facilities. Our analysis makes use of state of the art chlorine gas-grain chemical models and newly calculated HCl-H2 hyperfine collisional excitation rate coefficients. A narrow emission component in the HCl lines traces the extended envelope, and a broad one traces a more compact central region. The gas-phase HCl abundance in FIR 4 is 9e-11, a factor of only 0.001 + that of volatile elemental chlorine. The H2Cl lines are detected in absorption and trace a tenuous foreground cloud, where we find no depletion of volatile chlorine. Gas-phase HCl is the tip of the chlorine iceberg in protostellar cores. Using a gas-grain chemical model, we show that the hydrogenation of atomic chlorine on grain surfaces in the dark cloud stage sequesters at least 90% of the volatile chlorine into HCl ice, where it remains in the protostellar stage. About 10% of chlorine is in gaseous atomic form. Gas-phase HCl is a minor, but diagnostically key reservoir, with an abundance of <1e-10 in most of the protostellar core. We find the 35Cl/37Cl ratio in OMC-2 FIR 4 to be 3.2 ± 0.1, consistent with the solar system value. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1411.6483

Main-sequence stars masquerading as Young Stellar Objects in the central molecular zone Christine Koepferl1, Thomas Robitaille1, Esteban Morales1 and Katharine Johnston1 1 Max Planck Institute for Astronomy, Konigstuhl 17, 69117 Heidelberg, Germany E-mail contact: koepferl at mpia.de In contrast to most other galaxies, star-formation rates in the Milky Way can be estimated directly from Young Stellar Objects (YSOs). In the Central Molecular Zone (CMZ) the star-formation rate calculated from the number of YSOs

29 with 24 microns emission is up to order of magnitude higher than the value estimated from methods based on diffuse emission (such as free-free emission). Whether this effect is real or whether it indicates problems with either or both star formation rate measures is not currently known. In this paper, we investigate whether estimates based on YSOs could be heavily contaminated by more evolved objects such as main-sequence stars. We present radiative transfer models of YSOs and of main-sequence stars in a constant ambient medium which show that the main-sequence objects can indeed mimic YSOs at 24 microns. However, we show that in some cases the main-sequence models can be marginally resolved at 24 microns, whereas the YSO models are always unresolved. Based on the fraction of resolved MIPS 24 microns sources in the sample of YSOs previously used to compute the star formation rate, we estimate the fraction of misclassified ”YSOs” to be at least 63%, which suggests that the star-formation rate previously determined from YSOs is likely to be at least a factor of three too high. Accepted by ApJ http://arxiv.org/pdf/1411.4646

Near-IR Imaging Polarimetry toward a Bright-Rimmed Cloud: Magnetic Field in SFO 74 Takayoshi Kusune1, Koji Sugitani1, Jingqi Miao2, Motohide Tamura3,4, Yaeko Sato4, Jungmi Kwon3,4, Makoto Watanabe5, Shogo Nishiyama6, Takahiro Nagayama7 and Shuji Sato8 1 Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501, Japan 2 Centre for Astrophysics & Planetary Science, School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NR, UK 3 Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan 4 National Astronomical Observatory, 2-21-1 Osawa, Mikata, Tokyo 181-8588, Japan 5 Department of Cosmosciences, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan 6 Faculty of Education, Miyagi University of Education, Sendai 980-0845, Japan 7 Department of Physics, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan 8 Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan E-mail contact: t kusune at nsc.nagoya-cu.ac.jp We have made near-infrared (JHKs) imaging polarimetry of a bright-rimmed cloud (SFO 74). The polarization vector maps clearly show that the magnetic field in the layer just behind the bright rim is running along the rim, quite different from its ambient magnetic field. The direction of the magnetic field just behind the tip rim is almost perpendicular to that of the incident UV radiation, and the magnetic field configuration appears to be symmetric as a whole with respect to the cloud symmetry axis. We estimated the column and number densities in the two regions (just inside and far inside the tip rim), and then derived the magnetic field strength, applying the Chandrasekhar-Fermi method. The estimated magnetic field strength just inside the tip rim, 90 uG, is stronger than that far inside, 30 uG. This suggests that the magnetic field strength just inside the tip rim is enhanced by the UV radiation induced shock. The shock increases the density within the top layer around the tip, and thus increases the strength of the magnetic field. The magnetic pressure seems to be comparable to the turbulent one just inside the tip rim, implying a significant contribution of the magnetic field to the total internal pressure. The mass-to-flux ratio was estimated to be close to the critical value just inside the tip rim. We speculate that the flat-topped bright rim of SFO 74 could be formed by the magnetic field effect. Accepted by Astrophysical Journal http://arxiv.org/pdf/1411.1813

Magnetic ﬁeld structure in the Flattened Envelope and Jet in the young protostellar system HH 211 Chin-Fei Lee1, Ramprasad Rao1, Tao-Chung Ching2, Shih-Ping Lai2, Naomi Hirano1, Paul T.P. Ho1,3 and Hsiang-Chih Hwang1 1 Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan 2 Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

30 3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA E-mail contact: cflee at asiaa.sinica.edu.tw HH 211 is a young Class 0 protostellar system, with a flattened envelope, a possible rotating disk, and a collimated jet. We have mapped it with the Submillimeter Array in 341.6 GHz continuum and SiO J=8-7 at ∼ 0.′′6 resolution. The continuum traces the thermal dust emission in the flattened envelope and the possible disk. Linear polarization is detected in the continuum in the flattened envelope. The field lines implied from the polarization have different orientations, but they are not incompatible with current gravitational collapse models, which predict different orientation depending on the region/distance. Also, we might have detected for the first time polarized SiO line emission in the jet due to the Goldreich-Kylafis effect. Observations at higher sensitivity are needed to determine the field morphology in the jet. Accepted by ApJL http://arxiv.org/pdf/1411.2184

A feedback-driven bubble G24.136+00.436: a possible site of triggered star formation Hong-Li Liu1,2, Yuefang Wu3, JinZeng Li1, Jing-Hua Yuan1, Tie Liu4 and Xiaoyi Dong3 1 National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China 2 University of Chinese Academy of Sciences, 100049 Beijing, China 3 Department of Astronomy, Peking University, 100871 Beijing, China 4 Korea Astronomy and Space Science Institute 776, Daedeokdae-ro, Yuseong-gu, Daejeon, Republic of Korea 305-348 E-mail contact: hlliu at nao.cas.cn We present a multi-wavelength study of the IR bubble G24.136+00.436. The J=1-0 observations of 12CO, 13CO and C18O were carried out with the Purple Mountain Observatory 13.7 m telescope. Molecular gas with a velocity of 94.8 −1 4 km s is found prominently in the southeast of the bubble, shaping as a shell with a total mass of ∼ 2 × 10 M⊙. It is likely assembled during the expansion of the bubble. The expanding shell consists of six dense cores. Their dense 3 −3 3 −1 (a few of 10 cm ) and massive (a few of 10 M⊙) characteristics coupled with the broad linewidths (> 2.5 km s ) suggest they are promising sites of forming high-mass stars or clusters. This could be further consolidated by the detection of compact HII regions in Cores A and E. We tentatively identified and classified 63 candidate YSOs based on the Spitzer and UKIDSS data. They are found to be dominantly distributed in regions with strong emission of molecular gas, indicative of active star formation especially in the shell. The HII region inside the bubble is mainly ionized by a ∼O8V star(s), of the dynamical age ∼1.6 Myr. The enhanced number of candidate YSOs and secondary star formation in the shell as well as time scales involved, indicate a possible scenario of triggering star formation, signified by the “collect and collapse” process. Accepted by ApJ http://arxiv.org/pdf/1411.1226v1.pdf

Herschel/PACS view of disks around low-mass stars and brown dwarfs in the TW Hya association Yao Liu1,2, Gregory J. Herczeg3, Munan Gong4,5, Katelyn N. Allers6, Joanna M. Brown7, Adam L. Kraus8, Michael C. Liu9, Evgenya L. Shkolnik10, and Ewine F. van Dishoeck11,12 1 Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008, China 2 Key Laboratory for Radio Astronomy, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008, China 3 Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, Beijing 100871, China 4 Tsinghua University, Shuang Qing Lu 30, Haidian Qu, Beijing 100084, China 5 Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Peyton Hall, Princeton, NJ 08544, USA 6 Department of Physics and Astronomy, Bucknell University, Lewisburg, PA 17837, USA 7 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., MS 78, Cambridge, MA 02138, USA 8 Department of Astronomy, The University of Texas at Austin, Austin, TX 78712, USA

31 9 Institute for Astronomy, University of Hawaii at Manoa, 2680 Woodlawn Dr., Honolulu, HI 96822, USA 10 Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ, 86001, USA 11 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 12 Max-Planck-Institut fur Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany E-mail contact: yliu at pmo.ac.cn We conducted Herschel/PACS observations of five very low-mass stars or brown dwarfs located in the TW Hya association with the goal of characterizing the properties of disks in the low stellar mass regime. We detected all five targets at 70 µm and 100 µm and three targets at 160 µm. Our observations, combined with previous photometry from 2MASS, WISE, and SCUBA-2, enabled us to construct SEDs with extended wavelength coverage. Using sophisticated radiative transfer models, we analyzed the observed SEDs of the five detected objects with a hybrid fitting strategy that combines the model grids and the simulated annealing algorithm and evaluated the constraints on the disk properties via the Bayesian inference method. The modelling suggests that disks around low-mass stars and brown dwarfs are generally flatter than their higher mass counterparts, but the range of disk mass extends to well below the value found in T Tauri stars, and the disk scale heights are comparable in both groups. The inferred disk properties (i.e., disk mass, flaring, and scale height) in the low stellar mass regime are consistent with previous findings from large samples of brown dwarfs and very low-mass stars. We discuss the dependence of disk properties on their host stellar parameters and find a significant correlation between the Herschel far-IR fluxes and the stellar effective temperatures, probably indicating that the scaling between the stellar and disk masses (i.e., Mdisk ∝ M∗) observed mainly in low-mass stars may extend down to the brown dwarf regime. Accepted by A&A http://arxiv.org/pdf/1411.1858

Simulations of star formation in Ophiuchus, II: Multiplicity O. Lomax1, A. P. Whitworth1, D. A. Hubber2,3, D. Stamatellos4 and S. 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 Universe, Boltzmannstr. 2, D-85748 Garching, Germany 4 Jeremiah Horrocks Institute, University of Central Lancashire, Preston, Lancashire, PR1 2HE, UK 5 Physikalisches Institut, Universitat zu Koln, Zulpicher Strasse 77, D-50937 Cologne, Germany E-mail contact: oliver.lomax at astro.cf.ac.uk Lomax et al. have constructed an ensemble of 60 prestellar cores having masses, sizes, projected shapes, temperatures and non-thermal radial velocity dispersions that match, statistically, the cores in Ophiuchus; and have simulated the evolution of these cores using SPH. Each core has been evolved once with no radiative feedback from stars, once with continuous radiative feedback, and once with episodic radiative feedback. Here we analyse the multiplicity statistics from these simulations. With episodic radiative feedback, (i) the multiplicity frequency is 60% higher than in the field; (ii) the multiplicity frequency and the mean semi-major axis both increase with primary mass; (iii) one third of multiple systems are hierarchical systems with more than two components; (iv) in these hierarchical systems the inner pairings typically have separations of a few au and mass ratios concentrated towards unity, whereas the outer pairings have separations of order 100 au and a flatter distribution of mass ratios. The binary statistics are compatible with observations of young embedded populations, and – if wider orbits are disrupted preferentially by external perturbations – with observations of mature field populations. With no radiative feedback, the results are similar to those from simulations with episodic feedback. With continuous radiative feedback, brown dwarfs are under- produced, the number of multiple systems is too low, and the statistical properties of multiple systems are at variance with observation. This suggests that star formation in Ophiuchus may only be representative of global star formation if accretion onto protostars, and hence radiative feedback, is episodic. Accepted by MNRAS http://arxiv.org/pdf/1411.7943

32 Protostellar Jets Enclosed by Low-velocity Outflows Masahiro N. Machida1 1 Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan E-mail contact: machida.masahiro.018 at m.kyushu-u.ac.jp A protostellar jet and outflow are calculated for ∼ 270 yr following the protostar formation using a three dimensional magnetohydrodynamics simulation, in which both the protostar and its parent cloud are spatially resolved. A high- −1 −1 velocity (∼ 100kms ) jet with good collimation is driven near the disk’s inner edge, while a low-velocity (∼<10kms ) outflow with a wide opening angle appears in the outer-disk region. The high-velocity jet propagates into the low- velocity outflow, forming a nested velocity structure in which a narrow high-velocity flow is enclosed by a wide low- velocity flow. The low-velocity outflow is in a nearly steady state, while the high-velocity jet appears intermittently. The time-variability of the jet is related to the episodic accretion from the disk onto the protostar, which is caused by gravitational instability and magnetic effects such as magnetic braking and magnetorotational instability. Although the high-velocity jet has a large kinetic energy, the mass and momentum of the jet are much smaller than those of the low-velocity outflow. A large fraction of the infalling gas is ejected by the low-velocity outflow. Thus, the low-velocity outflow actually has a more significant effect than the high-velocity jet in the very early phase of the star formation. Accepted by The Astrophysical Journal Letters http://arxiv.org/pdf/1411.7124

Detections of trans-Neptunian ice M. K. McClure1, C. Espaillat2, N. Calvet1, E. Bergin1, P. D’Alessio3, D. M. Watson4, P. Manoj5, B. Sargent6 and L. I. Cleeves1 1 University of Michigan, USA 2 Boston University, USA 3 Universidad Nacional Autónoma de México, Mexico 4 University of Rochester, USA 5 Tata Institute of Fundamental Research, India 6 Rochester Institute of Technology, USA E-mail contact: mmcclure at eso.org We present Herschel Space Observatory PACS spectra of T Tauri stars, in which we detect amorphous and crystalline water ice features. Using irradiated accretion disk models, we determine the disk structure and ice abundance in each of the systems. Combining a model-independent comparison of the ice feature strength and disk size with a detailed analysis of the model ice location, we estimate that the ice emitting region is at disk radii >30AU, consistent with a proto-Kuiper belt. Vertically, the ice emits most below the photodesorption zone, consistent with Herschel observations of cold water vapor. The presence of crystallized water ice at a disk location a) colder than its crystallization temperature and b) where it should have been re-amorphized in ∼1 Myr suggests that localized generation is occurring; the most likely cause appears to be micrometeorite impact or planetesimal collisions. Based on simple tests with UV models and different ice distributions, we suggest that the SED shape from 20 to 50µm may probe the location of the water ice snow line in the disk upper layers. This project represents one of the first extra-solar probes of the spatial structure of the cometary ice reservoir thought to deliver water to terrestrial planets. Accepted by ApJ http://arxiv.org/pdf/1411.7618

Molecules with a peptide link in protostellar shocks: a comprehensive study of L1157 Edgar Mendoza1,2,3, B. Lefloch2,3, A. López-Sepulcre2,3, C. Ceccarelli2,3, C. Codella4, H. M. Boechat- Roberty1 and R. Bachiller5 1 Observatório do Valongo, Universidade Federal do Rio de Janeiro, Ladeira Pedro Antônio 43, CEP 20080-090, Rio de Janeiro, RJ, Brazil 2 Univ. Grenoble Alpes, IPAG, F-38000 Grenoble, France

33 3 CNRS, IPAG, F-38000 Grenoble, France 4 INAF, Osservatorio Astroﬁsico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy 5 IGN, Observatorio Astron´omico Nacional, Calle Alfonso XIII, 3 E-28004, Madrid, Spain E-mail contact: emendoza at astro.ufrj.br, mercurius.em at gmail.com

Interstellar molecules with a peptide link -NH-C(=O)-, like formamide (NH2CHO), acetamide (NH2COCH3) and isocyanic acid (HNCO) are particularly interesting for their potential role in pre-biotic chemistry. We have studied their emission in the protostellar shock regions L1157-B1 and L1157-B2, with the IRAM 30m telescope, as part of the ASAI Large Program. Analysis of the line proﬁles shows that the emission arises from the outﬂow cavities associated with B1 and B2. Molecular abundance of ≈ (0.4 − 1.1) × 10−8 and (3.3 − 8.8) × 10−8 are derived for formamide and isocyanic acid, respectively, from a simple rotational diagram analysis. Conversely, NH2COCH3 was not detected down to a relative abundance of a few ≤ 10−10. B1 and B2 appear to be among the richest Galactic sources of HNCO and NH2CHO molecules. A tight linear correlation between their abundances is observed, suggesting that the two species are chemically related. Comparison with astrochemical models favours molecule formation on ice grain mantles, with NH2CHO generated from hydrogenation of HNCO. Accepted by MNRAS (445, 151-161, 2014) http://arxiv.org/pdf/1408.4857

Stirring in massive, young debris discs from spatially resolved Herschel images A. Moór1, A.´ Kóspál1,2, P. Abrahám´ 1, D. Apai3, Z. Balog4, C. Grady5, Th. Henning4, A. Juhász6, Cs. Kiss1, A.V. Krivov7, N. Pawellek7, and Gy. M. Szabó1,8 1 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, PO Box 67, H-1525 Budapest, Hungary 2 European Space Agency (ESA-ESTEC, SRE-S), P.O. Box 299, 2200 AG, Noordwijk, The Netherlands; ESA fellow 3 Department of Astronomy and Department of Planetary Sciences, The University of Arizona, Tucson, AZ 85721 USA 4 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany 5 Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771 USA 6 Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden, The Netherlands 7 Astrophysikalisches Institut und Universitätssternwarte, Friedrich-Schiller-Universität Jena, Schillergäßchen 23, 07745 Jena, Germany 8 ELTE, Gothard Astrophysical Observatory, H-9704 Szombathely, Szent Imre hercegút 112, Hungary E-mail contact: moor at konkoly.hu A significant fraction of main-sequence stars are encircled by dusty debris discs, where the short-lived dust particles are replenished through collisions between planetesimals. Most destructive collisions occur when the orbits of smaller bodies are dynamically stirred up, either by the gravitational effect of locally formed Pluto-sized planetesimals (self- stirring scenario), or via secular perturbation caused by an inner giant planet (planetary stirring). The relative importance of these scenarios in debris systems is unknown. Here we present new Herschel Space Observatory imagery of 11 discs selected from the most massive and extended known debris systems. All discs were found to be extended at far-infrared wavelengths, five of them being resolved for the first time. We evaluated the feasibility of the self-stirring scenario by comparing the measured disc sizes with the predictions of the model calculated for the ages of our targets. We concluded that the self-stirring explanation works for seven discs. However, in four cases, the predicted pace of outward propagation of the stirring front, assuming reasonable initial disc masses, was far too low to explain the radial extent of the cold dust. Therefore, for HD 9672, HD 16743, HD 21997, and HD 95086, another explanation is needed. We performed a similar analysis for ß Pic and HR 8799, reaching the same conclusion. We argue that planetary stirring is a promising possibility to explain the disk properties in these systems. In HR 8799 and HD 95086 we may already know the potential perturber, since their known outer giant planets could be responsible for the stirring process. Our study demonstrates that among the largest and most massive debris discs self-stirring may not be the only active scenario, and potentially planetary stirring is responsible for destructive collisions and debris dust production in a number of systems.

34 Accepted by MNRAS http://arxiv.org/pdf/1411.5829

New low-mass members of the Octans stellar association and an updated 30–40 Myr lithium age Simon J. Murphy1,2 and Warrick A. Lawson2 1 Gliese Fellow, Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, D-69120 Hei- delberg, Germany 2 School of Physical, Environmental and Mathematical Sciences, University of New South Wales Canberra, ACT 2600, Australia E-mail contact: murphy at ari.uni-heidelberg.de The Octans association is one of several young stellar moving groups recently discovered in the Solar neighbourhood, and hence a valuable laboratory for studies of stellar, circumstellar disc and planetary evolution. However, a lack of low-mass members or any members with trigonometric parallaxes means the age, distance and space motion of the group are poorly constrained. To better determine its membership and age, we present the first spectroscopic survey for new K and M-type Octans members, resulting in the discovery of 29 UV-bright K5-M4 stars with kinematics, photometry and distances consistent with existing members. Nine new members possess strong Li I absorption, which allow us to estimate a lithium age of 30–40 Myr, similar to that of the Tucana-Horologium association and bracketed by the firm lithium depletion boundary ages of the β Pictoris (20 Myr) and Argus/IC 2391 (50 Myr) associations. Several stars also show hints in our medium-resolution spectra of fast rotation or spectroscopic binarity. More so than other nearby associations, Octans is much larger than its age and internal velocity dispersion imply. It may be the dispersing remnant of a sparse, extended structure which includes some younger members of the foreground Octans-Near association recently proposed by Zuckerman and collaborators. Accepted by MNRAS http://arxiv.org/pdf/1411.5703

Revealing the physical properties of molecular gas in Orion with a large scale survey in J = 2–1 lines of 12CO, 13CO and C18O Atsushi Nishimura1,2, Kazuki Tokuda1, Kimihiro Kimura1, Kazuyuki Muraoka1, Hiroyuki Maezawa1, Hideo Ogawa1, Kazuhito Dobashi3, Tomomi Shimoikura3, Akira Mizuno4, Yasuo Fukui5 and Toshikazu Onishi1 1 Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan 2 Nobeyama Radio Observatory, National Astronomical Observatory of Japan, 462-2 Nobeyama, Minamimaki, Mi- namisaku, Nagano, 384-1305, Japan 3 Department of Astronomy and Earth Sciences, Tokyo Gakugei University, 4-1-1 Nukuikita-machi, Koganei, Tokyo 184-8501, Japan 4 Solar-terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan 5 Department of Physics and Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan E-mail contact: atsushi.nishimura at nao.ac.jp We present fully sampled ∼ 3 arcmin resolution images of the 12CO(J = 2–1), 13CO(J = 2–1), and C18O(J = 2–1) emission taken with the newly developed 1.85-m mm-submm telescope toward the entire area of the Orion A and B giant molecular clouds. The data were compared with the J = 1–0 of the 12CO, 13CO, and C18O data taken with the Nagoya 4-m telescope and the NANTEN telescope at the same angular resolution to derive the spatial distributions of the physical properties of the molecular gas. We explore the large velocity gradient formalism to determine the gas density and temperature by using the line combinations of 12CO(J = 2–1), 13CO(J = 2–1), and 13CO(J = 1–0) assuming uniform velocity gradient and abundance ratio of CO. The derived gas density is in the range of 500 to 5000 cm−3, and the derived gas temperature is mostly in the range of 20 to 50 K along the cloud ridge with a temperature gradient depending on the distance from the star forming region. We found the high-temperature region at the cloud

35 edge facing to the HII region, indicating that the molecular gas is interacting with the stellar wind and radiation from the massive stars. In addition, we compared the derived gas properties with the Young Stellar Objects distribution obtained with the Spitzer telescope to investigate the relationship between the gas properties and the star formation activity therein. We found that the gas density and star formation eﬃciency are well positively correlated, indicating that stars form eﬀectively in the dense gas region. Accepted by ApJS http://arxiv.org/pdf/1412.0790.pdf

Shell instability of a collapsing dense core Evangelia Ntormousi1, Patrick Hennebelle1,2 1 Laboratoire AIM, Paris-Saclay, CEA/IRFU/SAp - CNRS - Université Paris Diderot, 91191, Gif-sur-Yvette Cedex, France 2 LERMA (UMR CNRS 8112), Ecole Normale Supérieure, 75231 Paris Cedex, France E-mail contact: eva.ntormousi at cea.fr Understanding the formation of binary and multiple stellar systems largely comes down to studying the circumstances for the fragmentation of a condensing core during the first stages of the collapse. However, the probability of fragmentation and the number of fragments seem to be determined to a large degree by the initial conditions. In this work we study the fate of the linear perturbations of a homogeneous gas sphere both analytically and numerically. In particular, we investigate the stability of the well-known homologous solution that describes the collapse of a uniform spherical cloud. The difficulty of the mathematical singularity in the perturbation equations is surpassed here by explicitly introducing a weak shock next to the sonic point. In parallel, we perform adaptive mesh refinement (AMR) numerical simulations of the linear stages of the collapse and compared the growth rates obtained by each method. With this combination of analytical and numerical tools, we explore the behavior of both spherically symmetric and non-axisymmetric perturbations. The numerical experiments provide the linear growth rates as a function of the core’s initial virial parameter and as a function of the azimuthal wave number of the perturbation. The overlapping regime of the numerical experiments and the analytical predictions is the situation of a cold and large cloud, and in this regime the analytically calculated growth rates agree very well with the ones obtained from the simulations. The use of a weak shock as part of the perturbation allows us to find a physically acceptable solution to the equations for a continuous range of growth rates. The numerical simulations agree very well with the analytical prediction for the most unstable cores, while they impose a limit of a virial parameter of 0.1 for core fragmentation in the absence of rotation. Accepted by A&A http://arxiv.org/pdf/1411.3177

The role of cosmic rays on magnetic field diffusion and the formation of protostellar discs Marco Padovani1,2,3, Daniele Galli3, Patrick Hennebelle4, Benoˆıt Commer¸con5 and Marc Joos4 1 Laboratoire Univers et Particules de Montpellier, UMR 5299 du CNRS, Universitéde Montpellier II, place E. Bataillon, cc072, 34095 Montpellier, France 2 Laboratoire de Radioastronomie Millimétrique, UMR 8112 du CNRS, Ecole´ Normale Supérieure et Observatoire de Paris, 24 rue Lhomond, 75231 Paris cedex 05, France 3 INAF–Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy 4 CEA, IRFU, SAp, Centre de Saclay, 91191 Gif-Sur-Yvette, France 5 Ecole´ Normale Supérieure de Lyon, CRAL, UMR 5574 du CNRS, UniversitéLyon I, 46 Allée d’Italie, 69364 Lyon cedex 07, France E-mail contact: Marco.Padovani at lupm.univ-montp2.fr The formation of protostellar discs is severely hampered by magnetic braking, as long as magnetic fields remain frozen in the gas. The latter condition depends on the levels of ionisation that characterise the innermost regions of a collapsing cloud. The chemistry of dense cloud cores and, in particular, the ionisation fraction is largely controlled by

36 cosmic rays. The aim of this paper is to evaluate whether the attenuation of the flux of cosmic rays expected in the regions around a forming protostar is sufficient to decouple the field from the gas, thereby influencing the formation of centrifugally supported disc. We adopted the method developed in a former study to compute the attenuation of the cosmic-ray flux as a function of the column density and the field strength in clouds threaded by poloidal and toroidal magnetic fields. We applied this formalism to models of low- and high-mass star formation extracted from numerical simulations of gravitational collapse that include rotation and turbulence. For each model we determine the size of the magnetic decoupling zone, where collapse or rotation motion becomes unaffected by the local magnetic field. In general, we find that decoupling only occurs when the attenuation of cosmic rays is taken into account with respect to a calculation in which the cosmic-ray ionisation rate is kept constant. The extent of the decoupling zone also depends on the dust grain size distribution and is larger if large grains (of radius ∼ 10−5 cm) are formed by compression and coagulation during cloud collapse. The decoupling region disappears for the high-mass case. This is due to magnetic field diffusion caused by turbulence that is not included in the low-mass models. We conclude that a realistic treatment of cosmic-ray propagation and attenuation during cloud collapse may lead to a value of the resistivity of the gas in the innermost few hundred AU around a forming protostar that is higher than generally assumed. Forthcoming self-consistent calculations should investigate whether this effect is strong enough to effectively decouple the gas from the field and to compute the amount of angular momentum lost by infalling fluid particles when they enter the decoupling zone. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1408.5901

Primordial mass segregation in simulations of star formation? Richard J. Parker1, James E. Dale2 and Barbara Ercolano2,3 1 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool, L3 5RF, UK 2 Excellence Cluster ‘Universe’, Boltzmannstraße 2, 85748 Garching, Germany 3 Universitäts-Sternwarte München, Scheinerstraße 1, 81679 München, Germany E-mail contact: R.J.Parker at ljmu.ac.uk We take the end result of smoothed particle hydrodynamics (SPH) simulations of star formation which include feedback from photoionisation and stellar winds and evolve them for a further 10 Myr using N-body simulations. We compare the evolution of each simulation to a control run without feedback, and to a run with photoionisation feedback only. In common with previous work, we find that the presence of feedback prevents the runaway growth of massive stars, and the resulting star-forming regions are less dense, and preserve their initial substructure for longer. The addition of stellar winds to the feedback produces only marginal differences compared to the simulations with just photoionisation feedback. We search for mass segregation at different stages in the simulations; before feedback is switched on in the SPH runs, at the end of the SPH runs (before N-body integration) and during the N-body evolution. Whether a simulation is primordially mass segregated (i.e. before dynamical evolution) depends extensively on how mass segregation is defined, and different methods for measuring mass segregation give apparently contradictory results. Primordial mass segregation is also less common in the simulations when star formation occurs under the influence of feedback. Further dynamical mass segregation can also take place during the subsequent (gas-free) dynamical evolution. Taken together, our results suggest that extreme caution should be exercised when interpreting the spatial distribution of massive stars relative to low-mass stars in simulations. Accepted by MNRAS http://arxiv.org/pdf/1411.3002

Magnetic Fields in High-Mass Infrared Dark Clouds Thushara Pillai1,2, Jens Kauﬀmann1,2, Jonathan C. Tan3, Paul F. Goldsmith4, Sean J. Carey5 and Karl M. Menten1 1 MPIfR, Germany 2 Caltech, USA

37 3 U. Florida, USA 4 JPL, USA 5 IPAC, Caltech, USA E-mail contact: tpillai.astro at gmail.com High-mass Stars are cosmic engines known to dominate the energetics in the Milky Way and other galaxies. However, their formation is still not well understood. Massive, cold, dense clouds, often appearing as Infrared Dark Clouds (IRDCs), are the nurseries of massive stars. No measurements of magnetic fields in IRDCs in a state prior to the onset of high-mass star formation (HMSF) have previously been available, and prevailing HMSF theories do not consider strong magnetic fields. Here, we report observations of magnetic fields in two of the most massive IRDCs in the Milky Way. We show that IRDCs G11.11-0.12 and G0.253+0.016 are strongly magnetized and that the strong magnetic field is as important as turbulence and gravity for HMSF. The main dense filament in G11.11-0.12 is perpendicular to the magnetic field, while the lower density filament merging onto the main filament is parallel to the magnetic field. The implied magnetic field is strong enough to suppress fragmentation sufficiently to allow HMSF. Other mechanisms reducing fragmentation, such as the entrapment of heating from young stars via high mass surface densities, are not required to facilitate HMSF. Accepted by ApJ http://arxiv.org/pdf/1410.7390

Infall-Driven Protostellar Accretion and the Solution to the Luminosity Problem Paolo Padoan1, Troels Haugbølle2 and Ake˚ Nordlund2 1 ICREA & University of Barcelona, Spain 2 Center for Star and Planet Formation, University of Copenhagen, Denmark E-mail contact: ppadoan at icc.ub.edu We investigate the role of mass infall in the formation and evolution of protostars. To avoid ad hoc initial and boundary conditions, we consider the infall resulting self-consistently from modeling the formation of stellar clusters in turbulent molecular clouds. We show that infall rates in turbulent clouds are comparable to accretion rates inferred from protostellar luminosities or measured in pre-main-sequence stars. They should not be neglected in modeling the luminosity of protostars and the evolution of disks, even after the embedded protostellar phase. We find large variations of infall rates from protostar to protostar, and large fluctuations during the evolution of individuals protostars. In −5 −1 most cases, the infall rate is initially of order 10 M⊙ yr , and may either decay rapidly in the formation of low-mass stars, or remain relatively large when more massive stars are formed. The simulation reproduces well the observed characteristic values and scatter of protostellar luminosities and matches the observed protostellar luminosity function. The luminosity problem is therefore solved once realistic protostellar infall histories are accounted for, with no need for extreme accretion episodes. These results are based on a simulation of randomly-driven magneto-hydrodynamic turbulence on a scale of 4 pc, including self-gravity, adaptive-mesh refinement to a resolution of 50 AU, and accreting sink particles. The simulation yields a low star formation rate, consistent with the observations, and a mass distribution of sink particles consistent with the observed stellar initial mass function during the whole duration of the simulation, forming nearly 1,300 sink particles over 3.2 Myr. Accepted by ApJ http://arxiv.org/pdf/1407.1445

Characterization of the known T type dwarfs towards the σ Orionis cluster K. Peña Ram´ırez1,2, M.R. Zapatero Osorio3, and V.J.S. Béjar4,5 1 Instituto de Astrof´ısica. Pontificia Universidad Católica de Chile (IA-PUC), E-7820436 Santiago, Chile 2 Millennium Institute of Astrophysics, Santiago, Chile 3 Centro de Astrobiolog´ıa(CSIC-INTA), Carretera de Ajalvir km 4, E-28850 Torrejón de Ardoz, Madrid, Spain 4 Instituto de Astrof´ısica de Canarias (IAC), C/. V´ıaLáctea s/n, E-38205 La Laguna, Tenerife, Spain 5 Universidad de La Laguna, Tenerife, Spain

38 E-mail contact: kpena at astro.puc.cl A total of three T type candidates (S Ori 70, S Ori73, and S Ori J0538−0213) lying in the line of sight towards σ Orionis were characterized by means of near-infrared photometric, astrometric, and spectroscopic studies. H-band methane images were collected for all three sources and an additional sample of 15 field T type dwarfs using LIRIS/WHT. J-band spectra of resolution of ∼500 were obtained for S Ori J0538−0213 with ISAAC/VLT, and JH spectra of resolution of ∼50 acquired with WFC3/HST were employed for the spectroscopic classification of S Ori 70 and 73. Proper motions with a typical uncertainty of ±3 mas yr−1 and a time interval of ∼7–9 yr were derived. Using the LIRIS observations of the field T dwarfs, we calibrated this imager for T spectral typing via methane photometry. The three S Ori objects were spectroscopically classified as T4.5±0.5 (S Ori 73), T5±0.5 (S Ori J0538−0213), and +0.5 T7−1.0 (S Ori 70). The similarity between the observed JH spectra and the methane colors and the data of field ultra-cool dwarfs of related classifications suggests that S Ori 70, 73, and S Ori J053804.65−021352.5 do not deviate significantly in surface gravity in relation to the field. Additionally, the detection of K i at ∼1.25 microns in S Ori J0538−0213 points to a high-gravity atmosphere. Only the K-band reddish nature of S Ori 70 may be consistent with a low gravity atmosphere. The proper motions of S Ori 70 and 73 are measurable and are larger than that of the cluster by >3.5σ. The proper motion of S Ori J0538−0213 is consistent with a null displacement. These observations suggest that none of the three T dwarfs are likely σ Orionis members, and that either planetary-mass objects with masses below ∼4 MJup may not exist free-floating in the cluster or they may lie at fainter near-infrared magnitudes than those of the targets (this is H > 20.6 mag), thus remaining unidentified to date. Accepted by A&A http://arxiv.org/pdf/1411.3370

Submillimeter Array Observations of Magnetic Fields in G240.31+0.07: An Hourglass in a Massive Cluster-forming Core Keping Qiu1, Qizhou Zhang2, Karl M. Menten3, Hauyu B. Liu4, Ya-Wen Tang4 and Josep M. Girart5 1 School of Astronomy and Space Science, Nanjing University, 22 Hankou Road, Nanjing 210093, China 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 3 Max-Planck-Institut fr Radioastronomie, Auf dem Hgel 69, D-53121 Bonn, Germany 4 Academia Sinica Institute of Astronomy and Astrophysics, P. O. Box 23-141, Taipei 106, Taiwan 5 Institut de Cincies de l’Espai (CSIC-IEEC), Campus UAB, Facultat de Cincies, C5p 2, E-08193 Bellaterra, Catalonia, Spain E-mail contact: kpqiu at nju.edu.cn We report the first detection of an hourglass magnetic field aligned with a well-defined outflow rotation system in a high-mass, star-forming region. The observations were performed with the Submillimeter Array toward G240.31+0.07, which harbors a massive, flattened, and fragmenting molecular cloud core and a wide-angle bipolar outflow. The polarized dust emission at 0.88 mm reveals a clear hourglass-shaped magnetic field aligned within 20 of the outflow + axis. Maps of high-density tracing spectral lines, e.g., H13CO (4-3), show that the core is rotating about its minor axis, which is also aligned with the magnetic field axis. Therefore, both the magnetic field and kinematic properties observed in this region are surprisingly consistent with the theoretical predictions of the classic paradigm of isolated low-mass star formation. The strength of the magnetic field in the plane of sky is estimated to be 1.1 mG, resulting in a mass-to-magnetic flux ratio of 1.4 times the critical value and a turbulent-to-ordered magnetic energy ratio of 0.4. We also find that the specific angular momentum almost linearly decreases from r ∼ 0.6 pc to 0.03 pc scales, which is most likely attributed to magnetic braking. Accepted by The Astrophysical Journal Letters http://arxiv.org/pdf/1409.5608

Collisionally Excited Filaments in HST Hα and Hβ Images of HH 1/2 A.C. Raga1, B. Reipurth2, A. Castellanos-Ram´ırez1, Hsin-Fang Chiang2 and J. Bally3 1 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ap. 70-543, 04510 D.F., México 2 Institute for Astronomy, University of Hawaii at Manoa, Hilo, HI 96720, USA

39 3 Center for Astrophysics and Space Astronomy, University of Colorado, UCB 389, Boulder, CO 80309, USA E-mail contact: [email protected] We present new Hα and Hβ images of the HH 1/2 system, and we ﬁnd that the Hα/Hβ ratio has high values in ridges along the leading edges of the HH 1 bow shock and of the brighter condensations of HH 2. These ridges have Hα/Hβ = 4 to 6, which is consistent with collisional excitation from the n = 1 to the n = 3 and 4 levels of hydrogen in a gas of temperatures T = 1.5 to 10×104 K. This is therefore the ﬁrst direct proof that the collisional excitation/ionization region of hydrogen right behind Herbig-Haro shock fronts is detected. Accepted by ApJ Letters http://arxiv.org/pdf/1411.7972

Fragmentation and Kinematics of dense molecular cores in the ﬁlamentary infrared-dark cloud G011.11-0.12 S. E. Ragan1, T. Henning1, H. Beuther1, H. Linz1 and S. Zahorecz1,2 1 Max Planck Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg, Germany 2 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei Muenchen, Germany E-mail contact: S.Ragan at leeds.ac.uk We present new Plateau de Bure Interferometer observations of a region in the ﬁlamentary infrared-dark cloud (IRDC) G011.11-0.12 containing young, star-forming cores. In addition to the 3.2 mm continuum emission from cold dust, + we map this region in the N2H (1-0) line to trace the core kinematics with an angular resolution of 2” and velocity −1 + resolution of 0.2 km s . These data are presented in concert with recent Herschel results, single-dish N2H (1- 0) data, SABOCA 350 µm continuum data, and maps of the C18O (2-1) transition obtained with the IRAM 30m + telescope. We recover the star-forming cores at 3.2mm continuum, while in N2H they appear at the peaks of + extended structures. The mean projected spacing between N2H emission peaks is 0.18 pc, consistent with simple isothermal Jeans fragmentation. The 0.1 pc-sized cores have low virial parameters on the criticality borderline, while + on the scale of the whole region, we infer that it is undergoing large-scale collapse. The N2H linewidth increases with evolutionary stage, while CO isotopologues show no linewidth variation with core evolution. Centroid velocities of all + tracers are in excellent agreement, except in the starless region where two N2H velocity components are detected, one of which has no counterpart in C18O. We suggest that gas along this line of sight may be falling into the quiescent core, giving rise to the second velocity component, possibly connected to the global collapse of the region. Accepted by A&A http://arxiv.org/pdf/1411.1911

Planet-induced disk structures: A comparison between (sub)mm and infrared radiation Jan Philipp Ruge1, Sebastian Wolf1, Ana L. Uribe2 and Hubert H. Klahr3 1 Universität zu Kiel, Institut für Theoretische und Astrophysik, Leibnitzstr. 15, 24098 Kiel, Germany 2 University of Chicago, The Department of Astronomy and Astrophysics, 5640 S. Ellis Ave, Chicago, IL 60637, USA 3 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany E-mail contact: ruge at astrophysik.uni-kiel.de Young giant planets, which are embedded in a circumstellar disk, will significantly perturb the disk density distribution. This effect can potentially be used as an indirect tracer for planets. We investigate the feasibility of observing planet- induced gaps in circumstellar disks in scattered light. We perform 3D hydrodynamical disk simulations combined with subsequent radiative transfer calculations in scattered light for different star, disk, and planet configurations. The results are compared to those of a corresponding study for the (sub)mm thermal re-emission. The feasibility of detecting planet-induced gaps in scattered light is mainly influenced by the optical depth of the disk and therefore by the disk size and mass. Planet-induced gaps are in general only detectable if the photosphere of the disks is sufficiently disturbed. Within the limitations given by the parameter space here considered, we find that gap detection is possible −4...−3 in the case of disks with masses below ∼ 10 M⊙. Compared to the disk mass that marks the lower Atacama Large (Sub)Millimeter Array (ALMA) detection limit for the thermal radiation re-emitted by the disk, it is possible to

40 −4 detect the same gap both in re-emission and scattered light only in a narrow range of disk masses around ∼ 10 M⊙, corresponding to 16% of cases considered in our study. Accepted by A&AL http://arxiv.org/pdf/1411.2735

Young Stellar Object candidates toward the Orion region selected from GALEX Nestor Sanchez1, Ana Inés Gómez de Castro1, Fátima Lopez-Martinez1, and Javier López-Santiago1 1 S.D. Astronom´ıay Geodesia, Fac. CC. Matemáticas, Universidad Complutense de Madrid, 28040 Madrid, Spain E-mail contact: nestorsa at ucm.es We analyze 359 ultraviolet tiles from the All Sky Imaging Survey of the space mission GALEX covering roughly 400 square degrees toward the Orion star-forming region. There is a total of 1,555,174 ultraviolet sources that were cross-matched with others catalogs (2MASS, UCAC4, SDSS, DENIS, CMC15 and WISE) to produce a list of 290,717 reliable sources with a wide range of photometric information. Using different color selection criteria we identify 111 Young Stellar Object candidates showing both ultraviolet and infrared excesses, of which 81 are new identifications. We discuss the spatial distribution, the spectral energy distributions and other physical properties of these stars. Their properties are, in general, compatible with those expected for T Tauri stars. This population of TTS candidates is widely dispersed around the Orion molecular cloud. Accepted by A&A http://arxiv.org/pdf/1411.0532

3D Dust Mapping Reveals that Orion Forms Part of a Large Ring of Dust E.F. Schlafly1, G. Green2, D.P. Finkbeiner2,3, H.-W. Rix1, W.S. Burgett4, K.C. Chambers4, P.W. Draper5, N. Kaiser4, N.F. Martin6,1, N. Metcalfe5, J.S. Morgan4, P. A. Price7, J.L. Tonry4, R.J. Wainscoat4, C. Waters4 1 Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg, Germany 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 3 Department of Physics, Harvard University, 17 Oxford Street, Cambridge MA 02138, USA 4 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu HI 96822, USA 5 Department of Physics, Durham University, South Road, Durham DH1 3LE, UK 6 Observatoire Astronomique de Strasbourg, CNRS, UMR 7550, 11 rue de lUniversite, F-67000 Strasbourg, France 7 Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA E-mail contact: schlafly at mpia.de The Orion Molecular Complex is the nearest site of ongoing high-mass star formation, making it one of the most extensively studied molecular complexes in the Galaxy. We have developed a new technique for mapping the 3D distribution of dust in the Galaxy using Pan-STARRS1 photometry. We isolate the dust at the distance to Orion using this technique, revealing a large (100 pc, 14 degree diameter), previously unrecognized ring of dust, which we term the ”Orion dust ring.” The ring includes Orion A and B, and is not coincident with current Hα features. The circular morphology suggests formation as an ancient bubble in the interstellar medium, though we have not been able to conclusively identify the source of the bubble. This hint at the history of Orion may have important consequences for models of high-mass star formation and triggered star formation. Accepted by ApJ http://arxiv.org/pdf/1411.5402

The Eﬀects of Initial Abundances on Nitrogen in Protoplanetary Disks Kamber Schwarz1 and Edwin Bergin1 1 University of Michigan, 1085 South University Ave., Ann Arbor, MI 48109, USA

41 E-mail contact: kamberrs at umich.edu The dominant form of nitrogen provided to most solar system bodies is currently unknown, though available measurements show that the detected nitrogen in solar system rocks and ices is depleted with respect to solar abundances and the interstellar medium. We use a detailed chemical/physical model of the chemical evolution of a protoplanetary disk to explore the evolution and abundance of nitrogen-bearing molecules. Based on this model we analyze how initial chemical abundances, provided as either gas or ice during the early stages of disk formation, influence which species become the dominant nitrogen bearers at later stages. We find that a disk with the majority of its initial nitrogen in either atomic or molecular nitrogen is later dominated by atomic and molecular nitrogen as well as NH3 and HCN ices, where the dominant species varies with disk radius. When nitrogen is initially in gaseous ammonia, it later becomes trapped in ammonia ice except in the outer disk where atomic nitrogen dominates. For a disk with the initial nitrogen in the form of ammonia ice the nitrogen remains trapped in the ice as NH3 at later stages. The model in which most of the initial nitrogen is placed in atomic N best matches the ammonia abundances observed in comets. Furthermore the + initial state of nitrogen influences the abundance of N2H , which has been detected in protoplanetary disks. Strong + −6 N2H emission is found to be indicative of an N2 abundance greater than nN2 /nH2 > 10 , in addition to tracing the CO snow line. Our models also indicate that NO is potentially detectable, with lower N gas abundances leading to higher NO abundances. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1411.1403.pdf

Magnetic field structure around cores with very low luminosity objects A. Soam1, G. Maheswar1, Chang Won Lee2,7, Sami Dib3,4, H.C. Bhatt5, Tamura Motohide6, and Gwanjeong Kim2,7 1 Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital 263002, India 2 Korea Astronomy & Space Science Institute (KASI), 776 Daedeokdae-ro, Yuseong-gu, Daejeon, Republic of Korea 3 Niels Bohr International Academy, Niels Bohr Institute, Blegdamsvej 17, DK-2100, Copenhagen, Denmark 4 Centre for Star and Planet Formation, University of Copenhagen, ster Voldgade 5-7., DK-1350, Copenhagen, Den- mark 5 Indian Institute of Astrophysics, Kormangala (IIA), Bangalore 560034, India 6 National Astronomical Observatory of Japan (NAOJ), Mitaka, Tokyo 181-8588, Japan 7 University of Science & Technology, 217 Gajungro, Yuseong-gu, Daejeon, 305-333, Korea E-mail contact: archana at aries.res.in We carried out optical polarimetry of five dense cores, (IRAM 04191, L1521F, L328, L673-7, and L1014) which are found to harbour VeLLO. This study was conducted mainly to understand the role played by the magnetic field in the formation of very low and substellar mass range objects using optical polarisation. The angular offsets between the envelope magnetic field direction (inferred from optical polarisation measurements) and the outflow position angles from the VeLLOs in IRAM 04191, L1521F, L328, L673-7, and L1014 are found to be 84◦, 53◦, 24◦, 08◦, and 15◦, respectively. The mean value of the offsets for all the five clouds is ∼ 37◦. If we exclude IRAM 04191, the mean value reduces to become ∼ 25◦. In IRAM 04191, the offset between the projected envelope and the inner magnetic field (inferred from the submillimetre data from SCUPOL) is found to be ∼ 68◦. The inner magnetic field, however, is found to be nearly aligned with the projected position angles of the minor axis, the rotation axis of the cloud, and the outflow from the IRAM 04191-IRS. We discuss a possible explanation for the nearly perpendicular orientation between the envelope and core scale magnetic fields in IRAM04191. The angular offset between the envelope magnetic field direction and the minor axis of IRAM 04191, L1521F, L673-7, and L1014 are 82◦, 60◦, 47◦, and 55◦, respectively. The mean value of the offsets between the envelope magnetic field and the minor axis position angles for the four cores is found to be ∼ 60◦. The results obtained from our study on the limited sample of five cores with VeLLOs show that the outflows in three of them tend to nearly align with the envelope magnetic field. Accepted by A&A http://arxiv.org/pdf/1411.0785

42 Alignment of Protostars and Circumstellar Disks During the Embedded Phase Christopher Spalding1, Konstantin Batygin1, and Fred C. Adams2,3 1 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA 2 Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA 3 Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA E-mail contact: cspaldin at caltech.edu Star formation proceeds via the collapse of a molecular cloud core over multiple dynamical timescales. Turbulence within cores results in a spatially non-uniform angular momentum of the cloud, causing a stochastic variation in orientation of the disk forming from the collapsing material. In the absence of star-disk angular momentum coupling, such disk-tilting would provide a natural mechanism for production of primordial spin-orbit misalignments in the resulting planetary systems. However, owing to high accretion rates in the embedded phase of star formation, the inner edge of the circumstellar disk extends down to the stellar surface, resulting in efficient gravitational and accretional angular momentum transfer between the star and the disk. Here, we demonstrate that the resulting gravitational coupling is sufficient to suppress any significant star-disk misalignment, with accretion playing a secondary role. The joint tilting of the star-disk system leads to a stochastic wandering of star-aligned bipolar outflows. Such wandering widens the effective opening angle of stellar outflows, allowing for more efficient clearing of the remainder of the protostar’s gaseous envelope. Accordingly, the processes described in this work provide an additional mechanism responsible for sculpting the stellar Initial Mass Function (IMF). Accepted by ApJL http://arxiv.org/pdf/1411.5431

The YSO Population in the Vela-D Molecular Cloud F. Strafella1, D. Lorenzetti2, T. Giannini2, D. Elia3, Y. Maruccia1, B. Maiolo1, F. Massi4, L. Olmi4, S. Molinari3, S. Pezzuto3 1 Dipartimento di Matematica e Fisica, Universitádel Salento, I-73100 Lecce, Italy 2 INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio, Italy 3 INAF-IAPS, via Fosso del Cavaliere 100, I-00133 Roma, Italy 4 INAF-Osservatorio di Arcetri, Largo E.Fermi 5, I-50125 Firenze, Italy E-mail contact: francesco.strafella at le.infn.it We investigate the young stellar population in the Vela Molecular Ridge, Cloud-D (VMR-D), a star forming (SF) region observed by both Spitzer/NASA and Herschel/ESA space telescope. The point source, band-merged, Spitzer- IRAC catalog complemented with MIPS photometry previously obtained is used to search for candidate young stellar objects (YSO), also including sources detected in less than four IRAC bands. Bona fide YSO are selected by using appropriate color-color and color-magnitude criteria aimed to exclude both Galatic and extragalactic contaminants. The derived star formation rate and efficiency are compared with the same quantities characterizing other SF clouds. Additional photometric data, spanning from the near-IR to the submillimeter, are used to evaluate both bolometric luminosity and temperature for 33 YSOs located in a region of the cloud observed by both Spitzer and Herschel. The luminosity-temperature diagram suggests that some of these sources are representative of Class 0 objects with bolometric temperatures below 70 K and luminosities of the order of the solar luminosity. Far IR observations from the Herschel/Hi-GAL key project for a survey of the Galactic plane are also used to obtain a band-merged photometric catalog of Herschel sources aimed to independently search for protostars. We find 122 Herschel cores located on the molecular cloud, 30 of which are protostellar and 92 starless. The global protostellar luminosity function is obtained by merging the Spitzer and Herschel protostars. Considering that 10 protostars are found in both Spitzer and Herschel list it follows that in the investigated region we find 53 protostars and that the Spitzer selected protostars account for approximately two-thirds of the total. Accepted by ApJ http://arxiv.org/pdf/1411.2758

43 Herschel Far IR observations of the giant HII region NGC 3603 F. Strafella1, D. Lorenzetti2, T. Giannini2, D. Elia3, Y. Maruccia1, B. Maiolo1, F. Massi4, L. Olmi4, S. Molinari3, S. Pezzuto3 1 Dipartimento di Matematica e Fisica, Universitádel Salento, I-73100 Lecce, Italy 2 INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio, Italy 3 INAF-IAPS, via Fosso del Cavaliere 100, I-00133 Roma, Italy 4 INAF-Osservatorio di Arcetri, Largo E.Fermi 5, I-50125 Firenze, Italy E-mail contact: francesco.strafella at le.infn.it We observed the giant HII region around the NGC 3603 YC with the 5 broad bands (70, 160, 250, 350, 500 µm) of the SPIRE and PACS instruments, on-board the Herschel Space Observatory. Together with what is currently known of the stellar, atomic, molecular and warm dust components, this additional and crucial information should allow us to better understand the details of the star formation history in this region. The main objective of the investigation is to study, at high spatial resolution, the distribution and main physical characteristics of the cold dust. By reconstructing −2 the temperature and density maps, we found respectively a mean value of 36 K and log(NH) = 22.0 ± 0.1 cm . We carried out a photometric analysis detecting 107 point-like sources, mostly confined to the North and South of the cluster. By comparing our data with SED models we found that 35 sources are well represented by YSOs in early evolutionary phases, from Class 0 to Class I. The Herschel detections also provided far-IR counterparts for 4 H2O masers and 11 objects previously known from mid-IR observations. The existence of so many embedded sources confirms the hypothesis of an intense and ongoing star formation activity in the region around NGC 3603 YC. Accepted by ApJ http://arxiv.org/pdf/1411.3094

Chains of dense cores in the Taurus L1495/B213 complex M. Tafalla1 and A. Hacar2 1 Observatorio Astronómico Nacional (IGN), Alfonso XII 3, E-28014 Madrid, Spain 2 Institute for Astrophysics, University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna, Austria E-mail contact: m.tafalla at oan.es Context. Cloud fragmentation into dense cores is a critical step in the process of star formation. A number of recent observations show that it is connected to the filamentary structure of the gas, but the processes responsible for core formation remain mysterious. Aims. We studied the kinematics and spatial distribution of the dense gas in the L1495/B213 filamentary region of the Taurus molecular cloud with the goal of understanding the mechanism of core formation. + 18 Methods. We mapped the densest regions of L1495/B213 in N2H (1–0) and C O(2–1) with the IRAM 30m telescope, and complemented these data with archival dust-continuum observations from the Herschel Space Observatory. Results. The dense cores in L1495/B213 are significantly clustered in linear chain-like groups about 0.5 pc long. The internal motions in these chains are mostly subsonic and the velocity is continuous, indicating that turbulence dissipation in the cloud has occurred at the scale of the chains and not at the smaller scale of the individual cores. The + chains also present an approximately constant abundance of N2H and radial intensity profiles that can be modeled with a density law that follows a softened power law. A simple analysis of the spacing between the cores using an isothermal cylinder model indicates that the cores have likely formed by gravitational fragmentation of velocity- coherent filaments. Conclusions. Combining our analysis of the cores with our previous study of the large-scale C18O emission from the cloud, we propose a two-step scenario of core formation in L1495/B213. In this scenario, named “fray and fragment”, L1495/B213 originated from the supersonic collision of two flows. The collision produced a network of intertwined subsonic filaments or fibers (fray step). Some of these fibers accumulated enough mass to become gravitationally unstable and fragment into chains of closely-spaced cores. Accepted by Astronomy and Astrophysics http://arxiv.org/pdf/1412.1083v1

44 Fast molecular jet from L1157-mm M. Tafalla1, R. Bachiller1, B. Lefloch2,3, N. Rodr´ıguez-Fernández4, C. Codella5, A. López-Sepulcre2,3,6 and L. Podio5 1 Observatorio Astronómico Nacional (IGN), Alfonso XII 3, E-28014 Madrid, Spain 2 Univ. Grenoble Alpes, IPAG, F-38000 Grenoble, France 3 CNRS, IPAG, F-38000 Grenoble, France 4 CESBIO (UMR 5126), Obs. de Midi-Pyrénées (CNES, CNRS, Univ. Paul Sabatier, IRD), 31401 Toulouse, France 5 INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy 6 Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan E-mail contact: m.tafalla at oan.es Context. L1157-mm powers a molecular outflow that is well-known for its shock-induced chemical activity in several hot-spots. Aims. We have studied the molecular emission toward L1157-mm searching for a jet component responsible for these spots. Methods. We used the IRAM 30m telescope to observe the vicinity of L1157-mm in several lines of SiO. Results. The SiO(5–4) and SiO(6–5) spectra toward L1157-mm present blue and red detached components about 45 km s−1 away from the ambient cloud. These extremely high-velocity (EHV) components are similar to those found in the L1448 and IRAS 04166+2706 outflows and probably arise from a molecular jet driven by L1157-mm. Observations of off-center positions indicate that the jet is unresolved in SiO(5–4) (< 11′′). Conclusions. The EHV jet seen in SiO probably excites L1157-B1 and the other chemically active spots of the L1157 outflow. Accepted by Astronomy and Astrophysics http://arxiv.org/pdf/1412.1476v1

The massive eruptive Class I variable V723 Carinae Mauricio Tapia1, Miguel Roth2 and Paolo Persi3 1 Instituto de Astronomia, UNAM, Ensenada, Mexico 2 Las Campanas Observatory, CIW, Chile 3 INAF- Istituto Astrofisica e Planetologia Spaziale, Rome , Italy E-mail contact: mt at astrosen.unam.mx Near-IR observations from 1993 to 2014 of V723 Carinae confirm this to be a young eruptive variable embedded in the Car I PDR/dust cloud in NGC 3372. In 1993, it was fainter than 16.6 in JHK and went into outburst before 2003, reaching K ≃ 12.9 in 2004. Since then, V723 Car has suffered erratic flux variations of up to ∆K = 2 in timescales of years. The variations are also evident into the mid-infrared. The H − K index shows correlation with K, though the ratio ∆K/∆(H − K) differs from that expected from dust extinction. The 1.91 to 2.48 µm spectrum of V723 Car shows emission lines of H2 and also Brγ, as well as 2.3- 2.4 µm CO overtone band-heads. The system is extremely red (H − K ≥ 4), with mid- and far-IR colours of a Class I object. The fitted parameters of Robitaille et al.’s model to −3 the 1.6 to 850 µm SED of V723 Car indicate a system composed of a 10M⊙ central star with a 5.6 × 10 M⊙ disk 3 3 and a 1.6 × 10 M⊙ envelope with AV ∼ 55 of extinction. The total luminosity of the system is about 4 × 10 L⊙. V723 Car is the most luminous, most massive, most deeply embedded, and possibly the youngest of all the young eruptive variables known. Evidence is provided of a 5,000 AU-long jet of shocked gas extending to opposite sites of the star. The infrared properties of a nearby 10L⊙ Class I young stellar object, Car I-125, are also described, with variations in K typical of Herbig Ae/Be stars. Its near-IR spectrum is featureless except for bright Brγ line emission. Accepted by MNRAS ftp://ftp.astrosen.unam.mx/iauname/mt/preprints (connect as Guest)

45 Outward Motion of Porous Dust Aggregates by Stellar Radiation Pressure in Proto- planetary Disks Ryo Tazaki1 and Hideko Nomura2 1 Department of Astronomy, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan 2 Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan E-mail contact: rtazaki at kusastro.kyoto-u.ac.jp We study the dust motion at the surface layer of protoplanetary disks. Dust grains in surface layer migrate outward due to angular momentum transport via gas-drag force induced by the stellar radiation pressure. In this study, we calculate mass flux of the outward motion of compact grains and porous dust aggregates by the radiation pressure. The radiation pressure force for porous dust aggregates is calculated using the T-Matrix Method for the Clusters of Spheres. First, we confirm that porous dust aggregates are forced by strong radiation pressure even if they grow to be larger aggregates in contrast to homogeneous and spherical compact grains to which efficiency of radiation pressure becomes lower when their sizes increase. In addition, we find that the outward mass flux of porous dust aggregates with monomer size of 0.1 µm is larger than that of compact grains by an order of magnitude at the disk radius of 1 AU, when their sizes are several microns. This implies that large compact grains like calcium-aluminum rich inclusions (CAIs) are hardly transported to outer region by stellar radiation pressure, whereas porous dust aggregates like chondritic-porous interplanetary dust particles (CP-IDPs) are efficiently transported to comet formation region. Crystalline silicates are possibly transported in porous dust aggregates by stellar radiation pressure from inner hot region to outer cold cometary region in the protosolar nebula. Accepted by ApJ http://arxiv.org/pdf/1411.4751

Polytropic models of filamentary interstellar clouds – I. Structure and stability Claudia Toci1 and Daniele Galli2 1 Dipartimento di Fisica e Astronomia, Universitàdegli Studi di Firenze, Via G. Sansone 1, I-50019 Sesto Fiorentino, Italy 2 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy E-mail contact: claudia at arcetri.astro.it The properties of filamentary interstellar clouds observed at sub-millimetre wavelengths, especially by the Herschel Space Observatory, are analysed with polytropic models in cylindrical symmetry. The observed radial density profiles are well reproduced by negative-index cylindrical polytropes with polytropic exponent 1/3 < γp < 2/3 (polytropic index −3

Polytropic models of filamentary interstellar clouds – II. Helical magnetic fields Claudia Toci1 and Daniele Galli2 1 Dipartimento di Fisica e Astronomia, Universitàdegli Studi di Firenze, Via G. Sansone 1, I-50019 Sesto Fiorentino,

46 Italy 2 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy E-mail contact: claudia at arcetri.astro.it We study the properties of magnetised cylindrical polytropes as models for interstellar filamentary clouds, extending the analysis presented in a companion paper. We formulate the general problem of magnetostatic equilibrium in the presence of a helical magnetic field, with the aim of determining the degree of support or compression resulting from the magnetisation of the cloud. We derive scale-free solutions appropriate to describe the properties of the envelopes of filaments at radii larger than the flat-density region. In these solutions, the polytropic exponent determines the radial profiles of the density and the magnetic field. The latter decreases with radius less steeply than the density, and field lines are helices twisted over cylindrical surfaces. A soft equation of state supports magnetic configurations that preferentially compress and confine the filament, whereas in the isothermal limit the field provides support. For each value of the polytropic exponent, the Lorentz force is directed outward or inward depending on whether the pitch angle is below or above some critical value which is a function of the polytropic exponent only. Accepted by MNRAS http://arxiv.org/pdf/1410.6092

Star formation in Chamaeleon I and III: a molecular line study of the starless core population A.E. Tsitali1, A. Belloche1, R.T. Garrod2, B. Parise1,3, and K.M. Menten1 1 Max-Planck-Institut für Radioastronomie, Auf dem Hgel 69, 53121, Bonn, Germany 2 Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853-6801, USA 3 School of Physics and Astronomy, Cardiff University, Queen’s Buildings, The Parade, Cardiff CF24 3AA, UK E-mail contact: belloche at mpifr-bonn.mpg.de The Chamaeleon clouds are excellent targets for low-mass star formation studies. Cha I and II are actively forming stars while Cha III shows no sign of ongoing star formation. We aim to determine the driving factors that have led to the very different levels of star formation activity in Cha I and III and examine the dynamical state and possible evolution of the starless cores within them. Observations were performed in various molecular transitions with APEX and Mopra. Five cores are gravitationally bound in Cha I and one in Cha III. The infall signature is seen toward 8–17 cores in Cha I and 2–5 cores in Cha III, which leads to a range of 13–28% of the cores in Cha I and 10–25% of the cores in Cha III that are contracting and may become prestellar. Future dynamical interactions between the cores will not be dynamically significant in either Cha I or III, but the subregion Cha I North may experience collisions between cores + within ∼0.7 Myr. Turbulence dissipation in the cores of both clouds is seen in the high-density tracers N2H 1–0 and 17 18 HC3N 10–9. Evidence of depletion in the Cha I core interiors is seen in the abundance distributions of C O, C O, 34 + and C S. Both contraction and static chemical models indicate that the HC3N to N2H abundance ratio is a good evolutionary indicator in the prestellar phase for both gravitationally bound and unbound cores. In the framework of these models, we find that the cores in Cha III and the southern part of Cha I are in a similar evolutionary stage + and are less chemically evolved than the central region of Cha I. The measured HC3N/N2H abundance ratio and the evidence for contraction motions seen towards the Cha III starless cores suggest that Cha III is younger than Cha I Centre and that some of its cores may form stars in the future. The cores in Cha I South may on the other hand be transient structures. Accepted by A&A http://arxiv.org/pdf/1411.3741

The structure of disks around Herbig Ae/Be stars as traced by CO ro-vibrational emission G. van der Plas1,2,3, M.E. van den Ancker3, L. B. F. M. Waters2,4 and C. Dominik2,5 1 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 2 Astronomical Institute Anton Pannekoek, University of Amsterdam, PO box 94249, 1090 GE, Amsterdam, The Netherlands

47 3 European Southern Observatory, Karl-Schwarzschild-Str.2, D 85748 Garching bei München, Germany 4 SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands 5 Institute for Astrophysics, Radbout University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands E-mail contact: info at gerritvanderplas.com Aims We study the emission and absorption of CO ro-vibrational lines in the spectra of intermediate mass pre-main- sequence stars with the aim to determine both the spatial distribution of the CO gas and its physical properties. We also aim to correlate CO emission properties with disk geometry. Methods Using high-resolution spectra containing fundamental and first overtone CO ro-vibrational emission, observed with CRIRES on the VLT, we probe the physical properties of the circumstellar gas by studying its kinematics and excitation conditions. Results We detect and spectrally resolve CO fundamental ro-vibrational emission in 12 of the 13 stars observed, and in two cases in absorption. Conclusions Keeping in mind that we studied a limited sample, we find that the physical properties and spatial distribution of the CO gas correlate with disk geometry. Flaring disks show highly excited CO fundamental emission up to vu = 5, while self-shadowed disks show CO emission that is not as highly excited. Rotational temperatures range between 250-2000 K. The 13CO rotational temperatures are lower than those of 12CO. The vibrational temperatures in self-shadowed disks are similar to or slightly below the rotational temperatures, suggesting that thermal excitation or IR pumping is important in these lines. In flaring disks the vibrational temperatures reach as high as 6000 K, suggesting fluorescent pumping. Using a simple kinematic model we show that the CO inner radius of the emitting region is ≈10 au for flaring disks and ≤ 1 au for self-shadowed disks. Comparison with hot dust and other gas tracers shows that CO emission from the disks around Herbig Ae/Be stars, in contrast to T Tauri stars, does not necessarily trace the circumstellar disk up to, or inside the dust sublimation radius, Rsubl. Rather, the onset of the CO emission starts from ≈Rsubl for self-shadowed disks, to tens of Rsubl for flaring disks. It has recently been postulated that group I Herbig stars may be transitional disks and have gaps. Our CO observations are qualitatively in agreement with this picture. We identify the location of the CO emission in these group I disks with the inner rim of the outer disk after such a gap, and suggest that the presence of highly vibrationally excited CO emission and a mismatch between the rotational and vibrational temperature may be a proxy for the presence of moderately sized disk gaps in Herbig Ae/Be disks. Accepted by Astronomy and Astrophysics http://arxiv.org/pdf/1412.1311

A direct imaging search for close stellar and sub-stellar companions to young nearby stars Nikolaus Vogt1, Markus Mugrauer2, Ralph Neuhäuser2, Tobias O.B. Schmidt2, Alexander Contreras- Quijada1, and János G. Schmidt2 1 Instituto de F´ısica y Astronom´ıa, Universidad de Valpara´ıso, Chile, Avenida Gran Bretaña 1111, Valpara´ıso, Chile 2 Astrophysikalisches Institut und Universitäts-Sternwarte Jena, Schillergäßchen 2, D-07745 Jena, Germany E-mail contact: nikolaus.vogt at uv.cl

A total of 28 young nearby stars (ages ≤60 Myr) have been observed in the Ks-band with the adaptive optics imager Naos-Conica of the Very Large Telescope at the Paranal Observatory in Chile. Among the targets are ten visual binaries and one triple system at distances between 10 and 130 pc, all previously known. During a first observing epoch a total of 20 faint stellar or sub-stellar companion-candidates were detected around seven of the targets. These fields, as well as most of the stellar binaries, were re-observed with the same instrument during a second epoch, about one year later. We present the astrometric observations of all binaries. Their analysis revealed that all stellar binaries are co-moving. In two cases (HD 119022 AB and FG Aqr B/C) indications for significant orbital motions were found. However, all sub-stellar companion-candidates turned out to be non-moving background objects except PZ Tel which is part of this project but whose results were published elsewhere. Detection limits were determined for all targets, and limiting masses were derived adopting three different age values; they turn out to be less than 10 Jupiter masses in most cases, well below the brown dwarf mass range. The fraction of stellar multiplicity and of the sub-stellar companion occurrence in the star forming regions in Chamaeleon are compared to the statistics of our search, and possible reasons for the observed differences are discussed.

48 Accepted by AN http://arxiv.org/pdf/1411.5438

Expanding Shell and Star Formation in the Infrared Dust Bubble N6 Jing-Hua Yuan1, Yuefang Wu2, Jin Zeng Li1 and Hong-Li Liu1 1 National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China 2 Department of Astronomy, Peking University, 100871 Beijing, China E-mail contact: jhyuan at nao.cas.cn We have carried out a multi-wavelength study of the infrared dust bubble N6 to extensively investigate the molecular environs and star-forming activities therein. Mapping observations in 12CO J =1 − 0 and 13CO J =1 − 0 performed with the Purple Mountain Observatory 13.7-m telescope have revealed four velocity components. Comparison between distributions of each component and the infrared emission suggests that three components are correlated with N6. There are ten molecular clumps detected. Among them, five have reliable detection in both 12CO and 13CO and have similar LTE and non-LTE masses ranging from 200 to higher than 5,000 M⊙. With larger gas masses than virial masses, these five clumps are gravitationally unstable and have potential to collapse to form new stars. The other five clumps are only reliably detected in 12CO and have relatively small masses. Five clumps are located on the border of the ring structure and four of them are elongated along the shell. This is well in agreement with the collect and collapse scenario. The detected velocity gradient reveals that the ring structure is still under expansion due to stellar winds from the exciting star(s). Furthermore, 99 young stellar objects have been identified based on their infrared colors. A group of YSOs reside inside the ring, indicating active star formation in N6. Although no confirmative features of triggered star formation detected, the bubble and the enclosed HII region have profoundly reconstructed the natal could and altered the dynamics therein. Accepted by the Astrophysical Journal http://arxiv.org/pdf/1411.0767

Kinematics of the Outflow From The Young Star DG Tau B: Rotation in the vicinities of an optical jet Luis A. Zapata1, Susana Lizano1, Luis F. Rodr´ıguez1, Paul T. P. Ho2,3, Laurent Loinard1, Manuel Fernández-López3, and Daniel Tafoya1 1Centro de Radioastronom´ıay Astrof´ısica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Mich., México 2Academia Sinica Institute of Astronomy and Astrophysics, Taipei, Taiwan 3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 4Astronomy Department, University of Illinois, 1002 West Green Street, Urbana, IL 61801, USA E-mail contact: [email protected] We present 12CO(2-1) line and 1300 µm continuum observations made with the Submillimeter Array (SMA) of the young star DG Tau B. We find, in the continuum observations, emission arising from the circumstellar disk surrounding DG Tau B. The 12CO(2-1) line observations, on the other hand, revealed emission associated with the disk and the asymmetric outflow related with this source. Velocity asymmetries about the flow axis are found over the entire length of the flow. The amplitude of the velocity differences is of the order of1–2kms−1 over distances of about 300 – 400 AU. We interpret them as a result of outflow rotation. The sense of the outflow and disk rotation is the same. Infalling gas from a rotating molecular core cannot explain the observed velocity gradient within the flow. Magneto- centrifugal disk winds or photoevaporated disk winds can produce the observed rotational speeds if they are ejected from a keplerian disk at radii of several tens of AU. Nevertheless, these slow winds ejected from large radii are not very massive, and cannot account for the observed linear momentum and angular momentum rates of the molecular flow. Thus, the observed flow is probably entrained material from the parent cloud. DG Tau B is a good laboratory to model in detail the entrainment process and see if it can account for the observed angular momentum. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1411.0173

49 ALMA reveals a candidate hot and compact disk around the O-type protostar IRAS 16547−4247 Luis A. Zapata1, Aina Palau1, Roberto Galván-Madrid1,2, Luis F. Rodr´ıguez1, Guido Garay3, James M. Moran4, and Ramiro Franco-Hernández3 1Centro de Radiostronom´ıay Astrof´ısica, Universidad Nacional Autónoma de México, Morelia, Michoacán, México 2European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany 3Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 4Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA E-mail contact: [email protected] We present high angular resolution (∼ 0.3′′) submillimeter continuum (0.85 mm) and line observations of the O- type protostar IRAS 16547−4247 carried out with the Atacama Large Millimeter/Submillimeter Array (ALMA). In the 0.85 mm continuum band, the observations revealed two compact sources (with a separation of 2′′), one of them associated with IRAS 16547−4247, and the other one to the west. Both sources are well resolved angularly, revealing a clumpy structure. On the other hand, the line observations revealed a rich variety of molecular species related to both continuum sources. In particular, we found a large number of S-bearing molecules, such as the rare molecule methyl mercaptan (CH3SH). At scales larger than 10,000 AU, molecules (e.g., SO2 or OCS) mostly with low excitation temperatures in the upper states (Ek ∼< 300 K) are present in both millimeter continuum sources, and show a southeast-northwest velocity gradient of 7 km s−1 over 3′′ (165 km s−1 pc−1). We suggest that this gradient probably is produced by the thermal (free-free) jet emerging from this object with a similar orientation at the base. At much smaller scales (about 1000 AU), molecules with high excitation temperatures (Ek ∼> 500 K) are tracing a rotating structure elongated perpendicular to the orientation of the thermal jet, which we interpret as a candidate disk surrounding IRAS 16547−4247. The dynamical mass corresponding to the velocity gradient of the candidate to disk is about 20 M⊙, which is consistent with the bolometric luminosity of IRAS 16547−4247. Accepted by The Monthly Notices of the Royal Astronomical Society http://arxiv.org/pdf/1411.7421

50 Abstracts of recently accepted major reviews

Gravitational Collapse and Disk Formation in Magnetized Cores S. Lizano1 and D. Galli2 1 Centro de Radioastronomia y Astrofisica, UNAM, Apdo. Postal 3-72, 58089 Morelia, Michoacan, Mexico 2 NAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125, Firenze, Italy E-mail contact: s.lizano at crya.unam.mx We discuss the effects of the magnetic field observed in molecular clouds on the process of star formation, concentrating on the phase of gravitational collapse of low-mass dense cores, cradles of sunlike stars. We summarize recent analytic work and numerical simulations showing that a substantial level of magnetic field diffusion at high densities has to occur in order to form rotationally supported disks. Furthermore, newly formed accretion disks are threaded by the magnetic field dragged from the parent core during the gravitational collapse. These disks are expected to rotate with a sub-Keplerian speed because they are partially supported by magnetic tension against the gravity of the central star. We discuss how sub-Keplerian rotation makes it difficult to eject disk winds and accelerates the process of planet migration. Moreover, magnetic fields modify the Toomre criterion for gravitational instability via two opposing effects: magnetic tension and pressure increase the disk local stability, but sub-Keplerian rotation makes the disk more unstable. In general, magnetized disks are more stable than their nonmagnetic counterparts; thus, they can be more massive and less prone to the formation of giant planets by gravitational instability. Accepted by “Magnetic Fields in Diffuse Media”, Springer-Verlag, eds. E. de Gouveia Dal Pino, A. Lazarian, C. Melioli, Chapter 16 http://arxiv.org/pdf/1411.6828

Astrochemistry of dust, ice and gas: introduction and overview Ewine F. van Dishoeck1 1 Leiden Observatory, Leiden University, The Netherlands E-mail contact: ewine at strw.leidenuniv.nl A brief introduction and overview of the astrochemistry of dust, ice and gas and their interplay is presented, aimed at non-specialists. The importance of basic chemical physics studies of critical reactions is illustrated through a number of recent examples. Such studies have also triggered new insight into chemistry, illustrating how astronomy and chemistry can enhance each other. Much of the chemistry in star- and planet-forming regions is now thought to be driven by gas-grain chemistry rather than pure gas-phase chemistry, and a critical discussion of the state of such models is given. Recent developments in studies of diﬀuse clouds and PDRs, cold dense clouds, hot cores, protoplanetary disks and exoplanetary atmospheres are summarized, both for simple and more complex molecules, with links to papers presented in this volume. In spite of many lingering uncertainties, the future of astrochemistry is bright: new observational facilities promise major advances in our understanding of the journey of gas, ice and dust from clouds to planets. Accepted by Faraday Discussions 2014, vol. 168, 9 http://arxiv.org/pdf/1411.5280

51 Dissertation Abstracts

Submillimeter studies of low mass star forming regions. Star formation in the Chamaeleon cloud complex

Anastasia Tsitali

Max-Planck Institute for Radio Astronomy Electronic mail: atsitali at gmail.com Ph.D dissertation directed by: Arnaud Belloche, Karl Menten Ph.D degree awarded: April 2014

The nearby molecular clouds Chamaeleon I and III (Cha I, Cha III) constitute excellent targets for low-mass star formation studies. Their large starless core population presents the opportunity to explore the earliest phases of star formation, prior to the formation of the protostellar object. The prestellar phase can offer valuable constraints for the initial conditions necessary for star formation to occur. The apparent similarity between the stellar initial mass function and the core mass distribution suggests that the prestellar core fragmentation plays a determining role in the subsequent evolution of the self-gravitating dense cores to stars. A deep understanding of the physical processes taking place during the prestellar phase and the dynamical evolution of these objects is therefore essential in order to constrain the multiple core collapse models and obtain a complete picture of star formation. The first part of the thesis focusses on an object in the Cha I molecular cloud, Cha-MMS1. Cha-MMS1 is very likely to be in the theoretically predicted intermediate evolutionary phase between the prestellar and protostellar phases, the first hydrostatic core. The dynamical state of this object is examined through molecular line observations obtained with the APEX and Mopra telescopes. The molecular emission is modelled using a radiative transfer code in order to derive constraints on the kinematics of the envelope, which are then compared to MHD simulations for the first core phase. Both the derived internal luminosity of Cha-MMS1 and the constrained infall velocity structure of the envelope are consistent with predictions of MHD simulations for the first core phase. Excess emission in high-density tracers additionally suggests the possible presence of a compact, slow outflow driven by Cha-MMS1, which is the main predicted observational signature of first cores. Overall, Cha-MMS1 does not belong to the prestellar phase. The kinematics of its envelope are consistent with a first hydrostatic core candidate, but it cannot be ruled out that this object might also be a Class 0 protostar. A future detection of a slow, compact outflow with ALMA would serve as definite proof that Cha-MMS1 is indeed a first hydrostatic core.

52 The second part of the thesis presents a molecular line survey that was conducted with the APEX and Mopra telescopes toward the starless core populations of the Cha I and III molecular clouds. Cha I is an actively star-forming whereas Cha III shows no sign of ongoing star formation. The main goal of this work is to determine the driving factors that have led to the strikingly different star formation activities in Cha I and III and to deduce the future dynamical evolution of the clouds. The kinematics of the starless cores are examined through a virial analysis and a search for infall motions. The chemical differences between Cha I and III are investigated through the observed fractional molecular abundances of the cores and by a comparison to predictions of chemical models. It is observationally derived that 15-30% of the Cha I cores and 10-25% of the Cha III cores will likely become prestellar and therefore form stars in the future. Interactions between the starless cores will not be dynamically significant in either cloud, thus eliminating competitive accretion as a likely process in these clouds. The analysis of the kinematics in the cores shows that turbulence has likely not affected the different star formation activities in Cha I and III. Nevertheless, a difference in chemistry between Cha I and III is seen in the fractional abundances of C18O and CH3OH. The HC3N to N2H+ abundance ratio is then examined as an evolutionary indicator in the prestellar phase through comparison to predictions of collapse and static chemical models. In the framework of these models, this abundance ratio is proven to be a good evolutionary tracer. An evolutionary ’gradient’ was thus seen within Cha I, with the cores in its southern part being younger than the cores in the central region of Cha I. The suggested interpretation is that the southern Cha I cores will undertake the same evolutionary path as the central Cha I cores, given that they belong to the same cloud. Interestingly, the Cha III cores have similar HC3N to N2H+ abundance ratios as the southern Cha I cores. Therefore, both the measured HC3N to N2H+ abundance ratio and the detected infall signatures indicate that Cha III is younger than Cha I, and therefore on the verge of forming stars. This conclusion points to the existence of an evolutionary sequence in the Chamaeleon complex, with the youngest Cha III cloud to the eldest Cha I cloud, and with Cha II likely at an intermediate evolutionary state. The dynamical state of Cha II is therefore worth investigating in the future through both an unbiased, continuum survey as well as molecular line observations. http://hss.ulb.uni-bonn.de/2014/3770/3770.htm

53 New Jobs

Postdoctoral position in molecular clouds and star formation

The Astrophysics Group at the University of Exeter invites applications for a postdoctoral position (Associate Research Fellow / Research Fellow) to work with Dr. Chris Brunt in the field of molecular clouds and star formation. This fixed-term position is funded by an STFC Consolidated Grant, and is available for 3 years (subject to a 12-month probationary period). The main aim of the project is deducing the 3D structure and dynamics of molecular clouds and relating this to star formation activity. This is primarily an observational position, though one which involves a substantial degree of modelling, including the use of supercomputer simulations. We are particularly interested in candidates with a background in mm/sub-mm spectral line observations, extinction mapping, and infrared continuum observations. Strong mathematical ability and coding proficiency would also be an asset, and applications from candidates from a numerical background will be seriously considered. Applicants must possess a PhD in astrophysics or a related discipline, or expect to have earned one before taking up the position. This position is available from April 2015, and start dates up to September 2015 may be possible. The starting salary will range from 25,513 on Grade E to 33,242 per annum on Grade F, depending on qualifications and experience. Extensive supercomputing resources and substantial funding for computing equipment and travel will be available. For further information about the position, or for advice on the application procedure, please contact Chris Brunt ([email protected]). Please apply via the University of Exeter online application system at jobs.exeter.ac.uk The job may be found by searching under ’Key words’ using post reference P48023 (accessible from Dec 1 2014 onwards). The closing date for applications is January 31 2015. Exeter Astrophysics Group website: http://emps.exeter.ac.uk/physics-astronomy/research/astrophysics/ Information for prospective University of Exeter employees: http://www.exeter.ac.uk/working/prospective/ Details on benefits for University of Exeter employees: http://www.exeter.ac.uk/staff/benefits/benefits/

Postdoctoral position in disc physics and planet migration University of Central Lancashire, UK

The Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy, of the University of Central Lancashire,UK, is seeking to appoint a postdoctoral research assistant to work with Dr. Dimitris Stamatellos on theoretical studies of planet formation and migration. This is a 3-year, STFC-funded position and it will be available from 1st April 2015, or as soon as possible thereafter. The successful applicant will be expected to have previous experience in computational astrophysics. Experience in hydrodynamics simulations (with SPH and/or grid methods) and in modelling protostellar discs and/or planet formation is highly desirable. Hands-on experience in using grid- and/or particle-based hydrodynamics codes for disc/planet dynamics simulations (e.g. FARGO, PENCIL, SEREN, GADGET) will be beneﬁcial. The project will make use of considerable computing resources, including the High Performance Computing facility of the University of Central Lancashire, as well as UK supercomputing facilities, such as DIRAC. The successful applicant will be appointed on Grade G (starting salary 28,695) and will receive the usual beneﬁts for employees in the UK (pension contribution, health insurance, annual leave, etc). Funds for computing resources and conference/collaboration travelling will also be provided.

54 The Jeremiah Horrocks Institute is comprised of nearly 30 staﬀ with a wide range of interests that cover theoretical and observational aspects of star formation, exoplanets, and life in the Universe (Prof. Derek Ward-Thompson - observational star formation, prestellar cores; Dr. Jason Kirk - observational star formation, prestellar cores; Prof. Don Kurtz - asteroseismology; Prof. Brad Gibson - Galactic habitable zones). The successful applicant will also have the chance to interact with Prof. S-I, Inutsuka (Nagoya University, Japan) through a collaborative project funded by a Royal Society Daiwa Anglo-Japanese Foundation International Exchanges Award. The Jeremiah Horrocks Institute is located on the University’s main campus, on a pleasant site in the centre of Preston. Preston itself is nestled on the edge of the beautiful Ribble Valley and the Forest of Bowland Area of Outstanding Natural Beauty. The Lake District, Peak District, and Yorkshire Dales are all within an hour’s drive. Both Manchester and Liverpool are just 45 minutes away. The closing date for applications is January 31st 2015. Interviews will be held on March 2nd. For informal inquires potential applicants may contact Dr Dimitris Stamatellos, either by email at [email protected] or by telephone on +44-(0)-1772-896418. Please apply online via http://www.uclan.ac.uk/jobs/.

Faculty Position in Exoplanet Studies

The School of Earth and Space Exploration (SESE) at Arizona State University invites applications for up to three tenure-track faculty positions in the area of exoplanet studies at either the assistant or associate professor level. Rank and tenure status will be commensurate with experience. Anticipated start date is August 2015. We are especially interested in candidates in the areas of exoplanet detection, interior modeling of exoplanets, atmospheric evolution, and instrumentation. Preference will be given to candidates who demonstrate the potential for interdisciplinary collaborations with ASU planetary scientists to better characterize exoplanets. Established in 2006, SESE is the focal point of Earth and space science at Arizona State University, one of the most dynamic and fastest growing institutions of higher learning in the United States. An essential part of SESE’s mission is to make new discoveries by promoting interdisciplinary science and by integrating science and engineering. SESE faculty and their research groups benefit from a variety of state-of-the-art facilities including access to the 2x8.4m Large Binocular Telescope, 6.5m MMT telescope, 6.5m Magellan telescopes and a host of 2m-class telescopes owned and operated by the State of Arizona. Broad, transdisciplinary collaborations between SESE astronomers, planetary scientists, Earth scientists, and engineers are actively encouraged (http://sese.asu.edu/people faculty). Minimum qualifications include: (1) a Ph.D. or equivalent in astronomy or astrophysics, planetary science, or a closely related discipline; (2) a strong research record in exoplanet studies established through publications in international peer-reviewed journals; and (3) a commitment to quality teaching and mentorship at the graduate and undergraduate levels. Candidates for consideration at the associate level must also have a demonstrated track record of externally funded research. To apply, please submit: 1) a cover letter not more than 3 pages long that includes a description of the applicant’s research and teaching interests and experience; 2) a current CV; and 3) the names, addresses, email addresses and telephone numbers of three references. All materials should be submitted in PDF format to [email protected]. Refer to Position #11029 in all correspondence. The application deadline is January 5, 2015; if not filled, reviews will continue weekly until the search is closed. A background check is required for employment. Arizona State University is a VEVRAA Federal Contractor and an Equal Opportunity/Affirmative Action Employer. All qualified applicants will be considered without regard to race, color, sex, religion, national origin, disability, protected veteran status, or any other basis protected by the law. http://www.asu.edu/aad/manuals/acd/acd401 http://www.asu.edu/titleIX/ The School of Earth & Space Exploration is an academic unit of the College of Liberal Arts and Sciences.

55 Three-year postdoctoral position on the formation of massive stars

The Astrophysics Group at the University of Exeter invites applications for a postdoctoral position (Associate Re- search Fellow / Research Fellow) to work with Tim Harries on radiation hydrodynamical simulations of massive star formation. This position is funded by an STFC Consolidated Grant, and is available for 3 years (subject to a 12-month probationary period). The main aim of this project is to investigate the role of radiation pressure and ionisation feedback on the formation of massive stars. This will be done using 3-D radiation hydrodynamical models, and by comparing the simulations with a broad range of multi-wavelength observational data. We are therefore particularly interested in applicants with a strong background in radiation transfer and/or hydrodynamics; prior work on star formation simulations would also be an asset, but all applicants with a good numerical astrophysics background will be seriously considered. Applicants must possess a PhD in astrophysics or a related discipline, or expect to have earned one before taking up the position. This position is available from 1st April 2015, although a later start date may be possible. The starting salary will range from GBP 25,513 on Grade E to GBP 33,242 per annum on Grade F, depending on qualiﬁcations and experience. Extensive supercomputing resources and substantial funding for computing equipment and travel will be available. For further information contact Tim Harries ([email protected]). Please apply via the University of Exeter online application system https://jobs.exeter.ac.uk. The job may be found by searching under ’Key words’ using post reference P48022. The closing date for applications is the 31st January 2015.

56 Meetings

Gordon Research Conference on Origins of Solar Systems

The 2015 Gordon Research Conference on Origins of Solar Systems will be held from June 28-July 3, 2015. The Gordon Conference on Origins of Solar Systems brings together a diverse group of scientists to discuss research at the frontier of understanding how planets and planetary systems form. Invited speakers from the ﬁelds of astronomy, astrophysics, cosmochemistry, planetary science, and geochemistry will present their latest ﬁndings. Particular topics of discussion will include: what meteorites tell us about the birth environment of our Solar System and planetary building blocks, how asteroids and icy bodies record the accretion epoch of the Solar System history, new observational and theoretical constraints on gas and dust in protoplanetary and debris disk systems, and how the properties of exoplanets are determined and what they tell us about how those planets formed. Conference website: http://www.grc.org/programs.aspx?id=12345

Workshop: The Formation of the Solar System II 2 - 4 June 2015 Berlin / Germany

Although the solar system formed more than 4.5 Gyr ago there still exist a number of indicators to the conditions at the time of its formation. Meteorites, the composition of the Kuiper belt and even today’ s properties of the solar system planets give clues to the solar system’s early history. However, there is an ongoing debate on how to interpret these properties. This second workshop ”The Formation of the Solar System II” again has the aim to bring together researchers working in the various ﬁelds involved in this quest. It turns out that this is a truly interdisciplinary endeavour, requiring knowledge of super novae explosions, meteorites, cosmochemistry, structure and evolution of circumstellar discs, star cluster dynamics, and the early dynamical evolution of planetary systems. Therefore contributions tackling the following subjects are welcome: * Cosmochemical constraints on the physical/chemical conditions in the Solar Nebula * Time scales of the dust and planetesimal growth for the Solar System * Models of the Kuiper belt formation * The role of the stellar environment, with emphasis on star cluster dynamics * Early planetary system development * Future evolution of the Solar System More information can be found at: https://indico.mpifr-bonn.mpg.de/FormationOfTheSolarSystem2 SOC: Melvyn Davies, Matthieu Gounelle, Pavel Kroupa, Alessandro Morbidelli, Simon Portegies Zwart, Susanne Pfalzner (Chair)

57 ’From interstellar clouds to star-forming galaxies: universal processes?’ Honolulu, August 3-7, 2015

IAU symposium 315 From interstellar clouds to star-forming galaxies: universal processes? will be held August 3-7, 2015 during the IAU General Assembly in Honolulu. The goal of this Symposium is to build a coherent picture of how star formation is fuelled and proceeds in galaxies. It will gather researchers working on this question with diﬀerent viewpoints: from the scale of Galactic molecular clouds to star-forming galaxies at high redshift. Key topics are:

• Atomic and molecular gas reservoirs in galaxies • From interstellar clouds to dense cores and protostellar disks • Stellar clusters, low- vs high-mass star formation, origin of the IMF • Star formation laws, rates, and thresholds in galaxies • Evolution of star formation with cosmic time and environment

Please see http://astronomy2015.org/symposium_315 for the titles of speciﬁc sessions and the full science rationale of the Symposium. Deadlines: abstract submission is 2015 March 18, and regular registration is 2015 May 23.

So far, the confirmed invited speakers include: M. Aravena, D. Arzoumanian, S. Basu, G. Chabrier, J. Di Francesco, D. Elbaz, B. Elmegreen, S. Garc´ıa-Burillo, S. Glover, P. Hopkins, A. Hughes, S. Inutsuka, A. Isella. J. Kenney, K. Kohno, A. Leroy, Z.-Y. Li, S. Madden, M.-M. Mac Low, S. Mart´ın, N. McClure-Griffiths, S. Molinari, F. Motte, P. Myers, S. Offner, M. Putman, L. Tacconi, M. Tafalla, J. Tan, S. Viti, C. Wilson.

With best wishes, Philippe Andr´e, Pascale Jablonka, Floris van der Tak co-Chairs of IAU symposium 315 on behalf of the SOC: Suzanne Aalto, Yuri Aikawa, Frank Bigiel, Alberto Bolatto, Fran¸coise Combes, Steve Eales, Neal Evans, Daisuke Iono, Jeremy Lim, Eve Ostriker, Monica Rubio, Kazushi Sakamoto, Jonathan Williams

58 Summary of Upcoming Meetings

The Kinematics of Star Formation: Theory and Observation in the Gaia Era 9 January 2015 London, UK http://www.star.herts.ac.uk/kinematics 45th “Saas-Fee Advanced Course”: From Protoplanetary Disks to Planet Formation 15-20 March 2015, Switzerland http://isdc.unige.ch/sf2015 The Soul of Massive Star Formation 15 - 20 March 2015 Puerto Varas, Chile http://www.das.uchile.cl/msf2015/ Star and Planet Formation in the Southwest 23 - 27 March 2015 Oracle, Arizona, USA https://lavinia.as.arizona.edu/~kkratter/SPF1/Home.html Milky Way Astrophysics from Wide-Field Surveys 30 March - 1 April 2015, London, Burlington House at the RAS, UK http://astro.kent.ac.uk/~df/gp/index.html Cloudy Workshop 4 - 8 May 2015 Warsaw, Poland http://cloud9.pa.uky.edu/~gary/cloudy/CloudySummerSchool/ Triple Evolution & Dynamics in Stellar and Planetary Systems 31 May - 5 June 2015 Haifa, Israel http://trendy-triple.weebly.com Workshop on the Formation of the Solar System II 2 - 4 June 2015 Berlin, Germany https://indico.mpifr-bonn.mpg/FormationOfTheSolarSystem2 IGM@50: is the Intergalactic medium driving Star Formation? 8 - 12 June 2015 Abbazia di Spineto, Italy http://www.arcetri.astro.it/igm50 30 Years of Photodissociation regions - A Symposium to honor David Hollenbach’s lifetime in science 28 June - 3 July 2015 http://pdr30.strw.leidenuniv.nl Gordon Research Conference on Origins of Solar Systems 28 June - 3 July 2015 http://www.grc.org/programs.aspx?id=12345 Disc dynamics and planet formation 29 June - 3 July 2015 Larnaka, Cyprus http://www.star.uclan.ac.uk/discs2015 From Interstellar Clouds to Star-forming Galaxies: Universal Processes? 3 - 7 August 2015 http://astronomy2015.org/symposium_315 Cosmic Dust 17 - 21 August 2015 Tokyo, Japan https://www.cps-jp.org/~dust/

59 Extreme Solar Systems III 29 November - 4 December 2015 Hawaii, USA http://ciera.northwestern.edu/Hawaii2015.php The 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun 6 - 10 June 2016 Uppsala, Sweden http://www.coolstars19.com Other meetings: http://www1.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/meetings/

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