252 — 11 December 2013 Editor: Bo Reipurth ([email protected]) List of Contents

252 — 11 December 2013 Editor: Bo Reipurth (Reipurth@Ifa.Hawaii.Edu) List of Contents

THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 252 — 11 December 2013 Editor: Bo Reipurth ([email protected]) List of Contents

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

Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers ...... 16 [email protected] Abstracts of Newly Accepted Major Reviews . 41 Technical Assistant: Hsi-Wei Yen Dissertation Abstracts ...... 43 [email protected] New Jobs ...... 44

Editorial Board Meetings ...... 46 Summary of Upcoming Meetings ...... 50 Joao Alves Alan Boss Obituary ...... 52 Jerome Bouvier Lee Hartmann Thomas Henning Paul Ho Jes Jorgensen Charles J. Lada Cover Picture Thijs Kouwenhoven The image shows the CG 30/31 cometary globule Michael R. Meyer complex pointing towards the center of the Gum Ralph Pudritz Nebula, where the massive stars ζ Puppis and γ Luis Felipe Rodr´ıguez Velorum reside. CG 30 is the prominent globule Ewine van Dishoeck to the left, it has an angular diameter of 2.3 ar- Hans Zinnecker cmin, which at an assumed distance of 450 pc cor- The Star Formation Newsletter is a vehicle for responds to 0.3 pc. The globule harbors two deeply fast distribution of information of interest for as- embedded newborn sources. The Herbig-Haro ob- tronomers working on star and planet formation ject HH 120 is seen towards the center of CG 30, and molecular clouds. You can submit material and another HH ﬂow, HH 950, is bursting out of for the following sections: Abstracts of recently the globule towards the southwest. Several T Tauri accepted papers (only for papers sent to refereed stars are located in front of the globule, indicating journals), Abstracts of recently accepted major re- previous episodes of triggered star formation. The views (not standard conference contributions), Dis- image is a composite of an Hα and a [SII] image. sertation Abstracts (presenting abstracts of new Image: Bo Reipurth – Processing: Robert Gendler Ph.D dissertations), Meetings (announcing meetings broadly of interest to the star and planet formation and early solar system community), New Jobs (advertising jobs speciﬁcally aimed towards persons within the areas of the Newsletter), and Short Announcements (where you can inform or re- Submitting your abstracts quest information from the community). Addition- ally, the Newsletter brings short overview articles Latex macros for submitting abstracts on objects of special interest, physical processes or and dissertation abstracts (by e-mail to theoretical results, the early solar system, as well [email protected]) are appended to each as occasional interviews. Call for Abstracts. You can also submit via the Newsletter web interface at http://www2.ifa. Newsletter Archive hawaii.edu/star-formation/index.cfm www.ifa.hawaii.edu/users/reipurth/newsletter.htm

2 A: In my early days it seemed that the only way to stop a massive cloud collapsing monolithically to form a sin- Anthony Whitworth gle star, was to invoke magnetic fields and/or rotation. I in conversation with Bo Reipurth think it’s fair to say that the roles played by turbulence and feedback had not really been appreciated by the majority of people working in the field, and many models were – some still are – based on notions of rather quasistatic condensation. In the late 80s I started to realise that the key to how stars form might lie in their binary statistics, and that probably most stars are conceived and born in highly dynamic and chaotic environments that could only be explored with numerical simulations. Indeed, the simulations of colliding clouds that we published in the early 90s showed stars and multiple systems condensing out of networks of filaments, but we weren’t too surprised, because the cosmologists had seen this sort of behaviour for some time. Q: The natural outcome of fragmentation is a binary or multiple system, and you have worked extensively in this Q: You got your first degree from Oxford and then moved area. Richard Larson once suggested that perhaps all stars to Manchester to get your PhD in 1972. Who was your form as multiples, which then break up into the distribution adviser and what was the subject of your thesis? of singles, binaries, and higher-order multiples we see in A: I was very fortunate to be supervised by Franz Kahn, the field. What do you think of that idea? who had extraordinary physical insight, and the capacity A: I think Larson was basically correct. In fact, we have to formulate quite complicated problems in a way that ad- just published a paper pointing out that, setting aside the mitted analytic solution (as, for example, his elegant and issue of high-mass stars, and using purely statistical argu- seminal analysis of the jump conditions across an ionisa- ments, the mapping from the observed Core Mass Func- tion/shock front). My thesis was on the structure of inter- tion to the Stellar Initial Mass Function is very hard to stellar clouds, solving transport equations to evaluate the understand unless a typical prestellar core spawns between dust temperature and the thermal and chemical balance of four and five stars, and at least one long-lived binary. the gas, using the then world-leading Manchester Univer- Moreover the mass of a core almost certainly increases sity supercomputer Atlas (and coding in Atlas Autocode, significantly, by accretion from its surroundings, between on punched tape!). I also benefitted from the wise counsel when the mass is evaluated for the purpose of constructing of Leon Mestel. the core mass function, and when the core is through with Q: You spent a postdoc in Leiden. What research did you spawning stars. focus on there? Q: Your most cited paper, together with D. Summers, deals A: In Leiden I continued to work on radiation transport, with the self-similar condensation of spherical gas clouds specifically against dust opacity, to calculate the temper- that are symmetric and self-gravitating. What were your atures of dust grains and the penetration of UV radia- main insights, and how has this field later developed? tion into clouds. I also started to consider star forma- A: This paper shows that there is a two-dimensional in- tion, using one-zone models to treat self-gravitating gas- finity of self-similar solutions for condensing isothermal dynamics. In 1974 I was offered a lectureship in the De- gas clouds, with one dimension representing the intrinsic partment of Applied Mathematics at Cardiff University, instability of the parent cloud and one representing the and joined a small group of astronomers and astrophysi- strength of the external impulse triggering condensation. cists there. The group was lead by Mike Disney, and we Apart from the singular case (which is sometimes referred subsequently moved into the Physics Department. Since to as inside-out collapse, but involves initial conditions then astronomy at Cardiff has grown and there is now a which even in the most bizarre circumstances nature could wide range of expertise from gravitational wave astronomy not be expected to deliver), they all involve an external to submillimetre and far-infrared instrumentation. Mike impulse, i.e. outside-in collapse. Furthermore, they all Disney taught me how to enjoy doing science, and I am deliver density profiles that go as r−2 at large radius and eternally grateful to him. r−3/2 at small radius; it seems that these features are sim- Q: Fragmentation has been a life-long interest of yours. ply the signature of approximately isothermal condensa- How has this subject developed conceptually over the years? tion.

3 Q: You were the lead-author of the PPV chapter on the of stars, sometimes only single multiple systems. At the theory of brown dwarf formation, a subject that has been same time the feedback from an Hii region appears always rather tempestuous. Was it difficult to keep the troops to- to be negative, in the sense that there is less star forma- gether? tion than there would have been without the ionising star. A: Yes, but it was also good fun, and we are still friends. However, what star formation does occur is accelerated by ii Moreover, there is still no consensus on how low-mass the expanding H region (i.e. it occurs much sooner), and hydrogen-burning stars and brown dwarfs form, so I sus- it is organised into shells and pillars and bright-rimmed pect that it would not be any different today, even though clouds. We have found no evidence for the collect and we should all be older and wiser. I continue to work collapse mechanism in our simulations, basically because on, and promote, the idea that as one moves from low- fractal clouds are so lumpy that they are susceptible to mass hydrogen-burning stars to brown dwarfs and on to radiation driven implosion. the opacity limit, an increasing fraction of stars (objects Q: After your retirement you have continued your research. formed by rapid dynamical collapse with uniform elemen- What are you currently working on? tal composition – as distinct from planets, which form by A: I retired one year ago, but was immediately re-employed, core accretion, on a much longer timescale, and with heav- and still work full time. I have had my heart re-plumbed ily fractionated elemental composition) is formed by disc by a brilliant Libyan surgeon, and feel about twenty years fragmentation. This belief has been under attack from younger. Of course, it also helps being able to work with, many quarters, and of course I may yet have to aban- and learn from, today’s smart young astrophysicists. My don it, but the theoretical arguments seem compelling to work divides between four main areas. (i) I am continu- me, and the observational constraints are still quite slack. ing to work with Steffi Walch, Richard Wünsch and Jim Moreover the simulations I have performed with Dimitri Dale, on the large-scale dynamics of star forming clouds, Stamatellos seem to show that disc fragmentation repro- in particular their formation, and their interaction with duces the observed statistical properties of brown dwarfs massive young stars. (ii) I have a big ongoing project, rather well – including the otherwise very puzzling one started with Simon Goodwin and Derek Ward-Thompson, that brown dwarfs that are distant companions to Sun- and continued with Patrick Hennebelle, Dimitri Stamatel- like stars appear to have a higher chance of being in a los and Oliver Lomax, to explore the collapse of cores; tight binary system with another brown dwarf than do the role of filaments, discs and accretion/feedback in their brown dwarfs in the field. fragmentation; and the origins of stellar multiplicity. This Q: Ten years ago you proposed with Hans Zinnecker the project includes the fascinating inverse problems involved interesting idea that photo-erosion of prestellar cores could in converting oberved images and line profiles into three- form brown dwarfs. Have you worked further on this mech- dimensional initial conditions, but we think we have found anism? a credible way of doing this, in a statistical sense, and A: Not really. The work I have done with Thomas Bis- the results are very promising; in particular, hierarchical bas and colleagues on numerical simulations of radiatively multiple systems (up to sextuplets) are quite common. I driven implosion were concerned with a different range of certainly do not subscribe to the rather common contem- parameters. I think this mechanism may occur occasion- porary assertion that low-mass star formation is more-or- ally, but I don’t think it is an important contributor to less sorted. (iii) I continue to work on the development the brown dwarf population. Firstly it is very inefficient, of improved and faster numerical methods, in the areas of and secondly it only works in the vicinity of ionising stars, Smoothed Particle Hydrodynamics and radiation trans- whereas many brown dwarfs are found in low-mass star port, in collaboration with David Hubber and Thomas formation regions. As I indicated above, my money (what Bisbas. (iv) I have returned to the project I started with little there is of it) is on disc fragmentation. Annabel Cartwright, on the development of statistical de- scriptors of structure in molecular clouds and young star Q: You have for many years been interested in the issue clusters, as a means of discerning the relationships be- of cloud dispersal by massive stars. What are your main tween observed clouds and clusters, and comparing them conclusions? with simulated ones. The Q parameter which we intro- A: With Steffi Walch, we have explored how the morphol- duced, and the minimal spanning tree that we first applied ogy of an Hii region depends on the fractal dimension of to the analysis of young star clusters in 1998, are now used the cloud in which it develops. It appears that if the cloud quite a bit, but this is an area in which much more needs has low fractal dimension, there is a tendency to form to be done. There never was a more exciting time to be partial shells, containing massive clumps that spawn star involved in astronomical research. clusters. Conversely, for high fractal dimension, there is a tendency to form pillars, and these contain small groups

4 for a variety of reasons parts of which I will describe below. However, I already apologize that I cannot mention and My Favorite Object cite all relevant studies investigating the properties of the The Herbig Ae/Be star HD100546 HD100546 system; there is much too much literature on this source and not enough space available here. For me, Sascha P. Quanz HD100546 was the ﬁrst Herbig Ae/Be star that I studied in some more detail and it seems as if this object will keep me busy for a few more years.

The central star

For my immediate research the central star has not the same importance as its surrounding circumstellar disk. However, with the mass of the central star being one of the key parameters in star and planet formation significantly affecting other parameters (e.g., the disk mass, size, lifetime), it’s useful to know the fundamental properties. HD100546 is located in the southern sky (11h 33m 25.4s; -70◦ 11′ 41.2′′) at a distance of 97±4 pc; it has a spectral type of B9Vne, an effective temperature of ∼10000±1000 K, an estimated mass of ∼2.4 M⊙, a luminosity of ∼26 L⊙ and an age of 5 – 10 Myr (Perryman et al. 1997; van Introduction Leeuwen et al. 2007; Houk & Cowley 1975; van den An- cker et al. 1997; Guimaraes et al. 2006; Tatulli et al. 2011). Spectroscopic studies show indications of ejection I have to admit that it was to some extent a coincidence but also accretion activities with mass accretion rates be- that I started working on Herbig Ae/Be stars. Initially, I −7 −9 tween ∼ 10 − 10 M⊙/yr (Pogodin et al. 2012; Grady was much more interested in young, low-mass (Sun-like) et al. 2007; Guimaraes et al. 2006). It is interesting stars and did not pay too much attention to the more massive siblings. Even though a few years back I was quite to mention that in a sample of 12 Herbig Ae/Be stars HD100546 appeared to be the most metal poor object with strongly exposed to the — admittedly interesting — work [Fe/H]= −1.4 ± 0.2 (Guimaraes et al. 2006). on Herbig Ae/Be stars primarily carried out by Dutch colleagues in Amsterdam and Leiden, I never quite got to the point to become passionate about these objects. How- General disk structure ever, things changed drastically when I decided to focus my research efforts on high-contrast imaging of circum- The circumstellar environment of HD100546 has been in- stellar disks and exoplanets. After several unsuccessful tensively studied by imaging campaigns using direct imag- attempts to image disks around TTauri stars in scattered ing from the ground (Pantin et al. 2000, J and K band) light from the ground, we decided to change strategy and and from space with HST NICMOS (1.6 µm), STIS, and include Herbig Ae/Be stars in our target list. Trying to ACS (F435W, F606W, F814W) (Augereau et al. 2001; image disks around Herbig Ae/Be stars offered some obser- Grady et al. 2001; Grady et al. 2005; Ardila et al. 2007). vational advantages, which soon paid of: Typically these In particular, the scattered light images across optical and disks are larger and more massive compared to TTauri NIR wavelengths of the latter studies revealed a complex disks and, in addition, at least some of them appear rather circumstellar structure interpreted as a large and flared isolated in the sky and are not immediately sitting in the circumstellar disk (RDisk≥ 300 AU) seen at intermediate strongly extincted regions of young star-forming regions. inclination angle and a remnant envelope. Figure 1 shows Also, with their central stars being brighter, these ob- a color-composite of the HST/ACS images published by jects are easier to observe with AO-assisted high-resolution Ardila et al. (2007). cameras from the ground. While most of these studies showed the larger scale struc- In this short article I will focus on quite a peculiar Herbig tures in great detail and revealed the existence of large Ae/Be star: HD100546. My impression is that HD100546 scale spiral arms (cf. Boccaletti et al. 2013), they did not has been basically observed with all instruments and tele- provide any information about the innermost regions close scopes that could point towards its very southern location. to the star (the inner 1 – 1.5′′ or so). Typically, with the To people working in this field, this object is well known central star being orders of magnitude brighter than the

5 Figure 1: Color-composite image of the circumstellar disk around HD100546 seen in scattered light with HST/ACS. The data were made publicly available by Ardila et al. (2007). 6′′ correspond to ∼600 AU at the distance of HD100546. The point sources in the image are ﬁeld stars.

faint signal of the surrounding circumstellar disk, coron- Figure 2: NACO/PDI images in the H band probing the agraphs and/or PSF subtraction techniques are applied inner regions of the HD100546 disk in scattered, polarized to cancel out the light contribution from the star and re- light (Avenhaus et al., in prep.). The images are roughly veal the disk. In doing so, the innermost disk regions 1.6′′ (∼160 AU) along the axes and were taken at two dif- are either hidden behind a coronagraph and/or are domi- ferent epoch (2006 top, 2013 bottom). The red cross indi- nated by PSF subtraction residuals rendering a quantita- cates the location of the star which has been canceled out tive analysis impossible. Using the high-spatial resolution, in the PDI process. The grey area in the center contains AO-assisted near-infrared camera system NACO installed no information as these regions were saturated. The outer at the VLT in Chile we imaged HD100546 in polarimet- edge of the disk gap is clearly detected at ∼13-15 AU, ric differential imaging (PDI) mode in the H and Ks filter where a strong increase in polarized flux is seen compared 1 (Quanz et al. 2011) . We probed the dusty disk surface in to the inner, darker regions right outside of the saturation the inner ∼10 – 150 AU and found observational evidence area. The disk major axis runs approximately along the for certain local sub-structures in the disk. Our images diagonal from the lower left to the top right corner. The further supported the idea that the disk has an inner cav- top left side of the disk is the far side, the bottom right ity or gap with a strong deficiency in dust particles inward side the near side of the disk (cf. Quanz et al. 2011). of ∼13 AU. A disk gap was already proposed based on SED models (Bouwman et al. 2003) and observationally confirmed with far UV spectra using HST/STIS (Grady et al. 2005). It’s worth noting that from rovibrational CO emis- PDI images obtained in the H band (Avenhaus et al. in sion lines, Brittain et al. (2009) found further evidence prep.). The gap edge is evident in both epochs. Whether for an inner cavity (∼13 AU radius) existing not only in or not the apparent change in brightness is significant and the dust but also in the gaseous component of the disk (at real is currently under investigation. Even closer to the least in CO). Qualitatively the same was found by van der star, inside of the inner working angle of our PDI images, Plas et al. (2009) although these authors could only put SED modeling and eventually interferometric observations a lower limit of 8 AU on the inner radius of the CO emis- in the NIR and MIR showed that there is an additional in- sion region. Figure 2 shows two epochs of VLT/NACO ner disk component (Bouwman et al. 2003; Benisty et al. 2010; Tatulli et al. 2011; Panićet al. 2012). While NIR 1 For recent PDI results of circumstellar disks, see abstracts from data seem to suggest that the disk stretches from ∼0.2 Avenhaus et al. and Garufi et al. in this issue of the SF Newsletter.

6 AU out to ∼4 AU (Tatulli et al. 2011), MIR observations 250 prefer a disk that is smaller than 0.7 AU in size (Pani´cet al. 2012). 200 Putting all these observations together, the circumstellar HD 100546 environment around HD100546 consists of an inner disk, ] 150

Jy Comet Hale-Bopp followed by a gap several AU wide, and a rather large [

ν outer disk extending outward to a few hundred AU all F 100 of which seems to be embedded in some remnant envelope material. While the inner disk is rather tenuous with −10 an estimated dust mass of only ∼ 10 M⊙ (Tatulli et 50 −3 Forsterite al. 2011), the outer disk contains more than 10 M⊙ in molecular gas (Pani´cet al. 2010). This general disk struc- 0 ture creates a quite unusual SED making HD100546 stand 10 20 30 40 λ µ out among other well studied Herbig Ae/Be systems: The [ m] NIR excess (mostly coming from the inner disk) is comparatively small, while the MIR excess (mostly coming from Figure 3: Comparison of the 5–40 micron spectrum of the puﬀed-up inner wall of the outer disk) is comparatively HD100546 and comet Hale Bopp (Crovisier et al. 1997; large (e.g., Bouwman et al. 2003). Malfait et al. 1998; Bouwman et al. 2003). Also shown is the spectrum of forsterite grains (Servoin & Piriou 1973). Image credit: Jeroen Bouwman. Dust and gas properties

In addition to its unusual SED, HD100546 shows a MIR emission spectrum, which sets the object apart from all scattered light images probe the dusty disk surface layer; the other Herbig Ae/Be objects. This spectrum shows finding grains that large at such large radii in the disk’s extremely strong indications for dust processing, i.e., a upper layers is further evidence for significant dust pro- significant amount of the dust grains are crystalline and cessing, but also challenging to explain in terms of the comparatively large grains (compared to the amorphous disk’s vertical structure. and sub-micron sized particles typically found in the ISM). Not only the dusty but also the gaseous component of In particular, the resemblance of the MIR spectrum to the HD100546 disk shows some remarkable peculiarities that of the comet Hale Bopp (Malfait et al. 1998) led to and has been studied in great detail. For instance, warm the conclusion that dust processing similar to that in our CH+ emission was detected and is thought to arise close own solar system must have taken place (Bouwman et al. to the disk rim at 10 - 13 AU (Thi et al. 2011). Also, 2003; van Boekel et al. 2005). Figure 3 shows the MIR HD100546 is one of the very few disks where NIR emission spectrum of HD100546 compared to that of Hale Bopp; of H2 lines was detected (Carmona et al. 2011), probably when I saw this figure for the first time I was blown away coming from the inner 50 AU of the disk. Given the spa- how similar these data look. tial extent of the emission, thermal excitation as emission Mulders et al. (2011) analyzed the location and compo- mechanism seems unlikely and an extended disk atmo- sition of the forsterite grains that dominate the spectrum sphere, where dust and gas are thermally decoupled in a in greater detail and concluded that the emission mostly hydrostatic disk or where photoevaporation creates a disk arises close to the outer edge of the disk gap. Also the wind, could be a plausible explanation. Further evidence spatially resolved emission of polycyclic aromatic hydro- for a warm gas atmosphere stretching out several tens of carbons (PAHs) observed at 3.3 µm seems to be confined AU comes from warm CO emission with excitation tem- to a small radial extent around ∼13 AU (Geers et al. peratures exceeding the local equilibrium temperature by 2007). The observations of the tenuous inner disk can several hundred degrees (Goto et al. 2012). Extensive be reproduced using micron-sized silicate particles whose studies using data from the Herschel Space Telescope con- albedos make the scattered light an important contribu- firmed the hypothesis of an extended and warm disk at- tion to the total NIR emission. Such fairly large grains are mosphere, where the gas is thermally decoupled from the also needed to make them survive (i.e., not sublimate too dust (Bruderer et al. 2012; Fedele at al. 2013). Interest- fast) at the inner edge of 0.24 AU, where the temperatures ingly, it seems as if this atmosphere has a high gas-to-dust are quite high. Finally, the scattered light images probing ratio and is poor in volatile carbon (Bruderer et al. 2012). disk regions >100 AU are best explained with aggregate A power-law fit to the CO line emission profiles and the dust grains which are also fairly large with a minimum size rotational ladder suggests a radial temperature gradient ∝ −0.85 of 2.5 µm (Mulders et al. 2013a). As mentioned above, following r and a very high temperature at the

7 disk rim of T = 1100 ± 350 K (Fedele et al. 2013). brown dwarf. A lot of information about the dust and gas content of the HD100546 disk is available, a signiﬁcant amount of which is spatially resolved. These data paint a complex picture of an apparently highly evolved disk where the density and temperature proﬁle of the gas and dust component are quite distinct.

Young planets orbiting in the disk?

In particular the suspected disk gap and the resulting extraordinary SED led to early speculations about possible ′ companions. Bouwman et al. (2003) proposed that a giant Figure 4: NACO ADI images of HD100546 in the L and M planet with 10 Jupiter masses orbiting at roughly 10 AU filter from spring 2013 (Quanz et al., to be submitted). An may have opened such a gap. Tatulli et al. (2011) used emission source is clearly detected in both filters north of hydro-simulations to reproduce the gap clearing and the the central star (yellow arrows) at the same location as the surface density jumps between the inner and outer disk young, planet candidate published in Quanz et al. (2013) ′ and concluded that a 1 to 8 Jupiter mass object orbit- based on earlier L observations from 2011. ing at 8 AU is consistent with the available data. Addi- tional observational support for a companion in the gap was provided by Acke & van den Ancker (2006) who ar- In addition to the suspected object orbiting in the disk gued that temporal changes in their [OI] line profile may gap, we discovered a second planet candidate by means be another signpost for the existence of the yet unseen 20 of direct imaging earlier this year (Quanz et al. 2013). Jupiter mass planet orbiting within the cavity. More re- Using VLT/NACO and combining the angular differen- cently, Liskowsky et al. (2012) observed asymmetric line tial imaging technique (ADI; Marois et al. 2006) with the profiles in the OH spectrum of HD100546. The asymme- apodizing phase plate (APP) coronagraph (Kenworthy et al. 2010) in the L′ filter, we found an emission source lo- tries are consistent with emission coming from an eccentric ′′ annulus near the disk rim possibly driven by an orbiting cated roughly ∼0.5 (de-projected 70 AU) from the central companion in the disk gap. An even more direct indica- star, i.e., right in the middle of the optically thick circum- tion of a close-in companion comes from non-axisymmetric stellar disk. This emission source was best explained with structures in the gaseous CO emission, which could be at- a combination of a point source component and some ex- tributes to a circumplanetary disk (Brittain et al. 2013). tended emission, and given its brightness and small separa- The spectroastrometric signal in the ν=1-0 CO emission tion from HD100546 it is unlikely a background object. If from HD100546 varies significantly over a baseline of sev- the observed luminosity arose solely from the photosphere eral years, and can be fit with emission from a non-varying of a young object then, according to the COND evolution- circumstellar disk plus a compact source of emission that ary models (Baraffe et al. 2003), the object’s mass would varies in velocity as it orbits the star (Brittain et al. 2013). be between 15 - 20 Jupiter masses. This, however, seems The required emitting area (∼0.1 AU2) of the orbiting unlikely as the gravitational influence of such an object component can be explained by a circumplanetary disk would significantly perturb the outer disk of HD100546 and is in agreement with model predictions (e.g., Ayliffe and cause significant sub-structures which have not been & Bate 2009). A first direct upper limit on possible com- observed so far. In Quanz et al. (2013) we argued that panions was provided by Grady et al. (2005) who could the object is a young, forming gas giant planet that still exclude a stellar companion inside the cavity, but not a undergoes gas accretion. This could explain both the ob- brown dwarf or planetary mass object. Recently, Mulders served luminosity (part of the luminosity is coming from et al. (2013b) used hydrodynamical simulations to model the accretion process via a circumplanetary disk) and the the rounded-off shape of the outer disk rim, which is con- apparently smooth circumstellar disk (the object is young strained by MIR interferometric data (Panićet al. 2012). and not yet very massive) at the same time. More re- In this picture, the rim is not a steep wall, but rather the cent data seem to confirm the general conclusions given in surface density increases gradually with radius. This ap- Quanz et al. (2013) although not all analyses are yet final- parent gradient in the rim’s surface density depends on the ized. In Figure 4 we show new images from VLT/NACO disk viscosity but also on the mass of the body orbiting taken in the L’ filter and also in the M filter (Quanz et al., in the disk gap and is, at least according to these models, to be submitted). The object is re-detected in both filters +20 with very high S/N at the same location as in the discov- best explained with a 60−40 Jupiter mass object, i.e., a ery paper. Interestingly, Boccaletti et al. (2013) presented

8 deep, high-contrast images taken at shorter wavelengths Already today, the complete census of existing data for in the Ks filter. The object was not detected even though HD100546 is very complex and every new dataset seems the detection limits were 16 - 18 Jupiter masses. While to trigger many more new questions than it is able to wavelength dependent extinction effects caused by the cir- answer. However, from what I have learned about this cumstellar disk material can not be excluded as possible object, I would say it is absolutely worth it. I doubt that explanation for the non-detection in the Ks band, these there are many other objects nearby in the sky where we data are also in good qualitative agreement with an ob- can learn in such great detail not only about the physics in ject that is only several hundred Kelvin warm and hence circumstellar disks but probably also about the processes comparatively faint in Ks. involved in the formation of gas giant planets. The data and models discussed in this section strongly References: support the idea that planet formation is actively ongoing Acke, B. & van den Ancker, M. E. 2006, A&A, 449, 267 in the HD100546 system. Even more exciting: There are Ardila, D. R., et al. 2007, ApJ, 665, 512 Augereau, J. C., et al. 2001, A&A, 365, 78 direct indications for at least two (planetary mass?) ob- Ayliffe, B.A. & Bate, M.R. 2009. MNRAS 397, 657 jects in the HD100546 disk. While a first object orbiting Baraffe, I., et al. 2003, A&A, 402, 701 somewhere between 8 and 13 AU probably carved out the Benisty, M., et al. 2010, A&A, 511, A75+ observed disk gap, a second — and presumably younger Boccaletti, A., et al. 2013, A&A 560, 20 Bouwman, J., et al. 2003, A&A, 401, 577 — object is located at ∼70 AU. If this picture was cor- Brittain, S. D., Najita, J. R., & Carr, J. S. 2009, ApJ, 702, 85 rect, we would be witnessing the sequential formation of Brittain, S. D., et al. 2013, ApJ767, 159 a new planetary system and had a unique laboratory to Bruderer, S., et al. 2012 A&A 541A, 91 study the physical and chemical conditions under which Carmona, A., et al. 2011, A&A 533A, 39 Crovisier, J., et al. 1997, Science 275, 1904 planet formation takes place. This is particularly inter- Fedele, D., et al. 2013, ApJ 776L, 3 esting because the vast majority of the directly imaged Geers, V. C., et al. 2007, A&A, 476, 279 planets known today orbit early-type stars on rather wide Goto, M., et al. 2012, A&A 539A, 81 orbits (∼10 - 70 AU; e.g., Marois et al. 2010; Lagrange et Grady, C. A., et al. 2001, AJ, 122, 3396 Grady, C. A., et al. 2005, ApJ, 620, 470 al. 2010; Rameau et al. 2013). How these objects with Grady, C. A., et al. 2007, ApJ, 665, 1391 masses of at least several times the mass of Jupiter formed Guimaraes, M. M., et al. 2006, A&A, 457, 581 is a subject of active research and possibly HD100546 al- Houk, N. & Cowley, A. P. 1975, University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. lows us to address some of the relevant questions observa- Kenworthy, M. A., et al 2010, in SPIE Conference Series, Vol. 7735 tionally. Lagrange, A.-M., et al. 2010, Science 329, 57 Liskowsky, J .P., et al. 2012, ApJ, 760, 153 Malfait, K., et al. 1998, A&A, 332, L25 Possible future work Marois, C., et al. 2006, ApJ, 641, 556 Marois, C., et al. 2010, Nature 468, 1080 Mulders, G. D., et al. 2011, A&A, 531, 93 Observationally for me it is clear that more data is needed Mulders, G. D., et al. 2013a, A&A 549, 112 to confirm and further constrain the properties of the pro- Mulders, G. D., et al. 2013b, A&A, 557, 68 posed (planetary mass) companions. Can we image the Panić, O., et al. 2010, A&A, 519, A110 inner planet directly? If it is indeed a young brown dwarf Panić, O., et al. 2012; arXiv 1203.6265 (submitted to A&A) Pantin, E., Waelkens, C., & Lagage, P. O. 2000, A&A, 361, L9 and/or still accreting then it should be fairly bright. Also, Perryman, M. A. C., et al. 1997, A&A, 323, L49 can we detect signs of ongoing accretion activity for both Pogodin, M.A., et al. 2012; AN 333, 594 objects? What constraints can we put observationally on Quanz, S.P., et al. 2011, ApJ 738, 23 the physical properties of circumplanetary disks, which Quanz, S.P., et al. 2013, ApJ, 766, 1 Rameau, J., et al. 2013, ApJ 772, 15 should be present if these objects are actively accreting? Servoin & Piriou 1973, phys. stat. sol. 55, 677 Here, we may be entering a completely new research field Tatulli, E.,et al. 2011, A&A, 531, A1 where empirical data has really not been existing so far. Thi, W.-F., et al. 2011, A&A 530L, 2 van Boekel, R., et al. 2005, A&A, 437, 189 Concerning the circumstellar disk it would certainly be in- van den Ancker, M. E., et al. 1997, A&A, 324, L33 teresting to probe the dust in the disk midplane and the van der Plas, G., et al. 2009, A$A, 500, 1137 gaseous disk component on the same spatial scales as done van Leeuwen, F. 2007, A&A, 474, 653 by the scattered light observations. ALMA should be able to do this. Density and temperature profiles, and discon- tinuities therein, as well as hints towards the composition in gas and dust as a function of disk radius may provide some interesting insights into the physical and chemical properties of a disk that apparently is actively forming planets.

9 On the other hand, dense cores within clouds were traced in smaller- scale maps of either emission from molecu- Perspective lar transitions excited by denser conditions (e.g., NH3 (1,1); Friesen et al. 2009) or continuum emission from Filamentary, My Dear Watson! dust (Motte, André& Neri 1998). Such core maps had generally higher resolutions than cloud maps (e.g., 15-30′′ James Di Francesco FWHM) but were spatially filtered either by limitations in line excitation or subtraction of large-scale continuum emission from the atmosphere. Despite these limitations, important insights about clouds and cores were still obtained. For clouds, CO line widths were found to be generally much larger than expected from thermal motions alone, implicating the occurrence of turbulence as a key ingredient to molecular cloud energetics. Indeed, line widths were seen to decrease with scale in a man- ner similar to that expected from compressible turbulence (Larson 1981), down to core scales where turbulent and thermal motions are comparable (e.g., see Goodman et al. 1998). Moreover, the mass distribution of cores, i.e., the core mass function (CMF), was revealed to have a shape very similar to that of stellar Initial Mass Function (IMF), Stars form within clouds of cold molecular gas that per- suggesting whatever process in clouds organizes material meate the disks of galaxies. In recent years, however, it into dense cores is ultimately responsible for the masses has become increasingly clear that star formation occurs of the stars formed (Motte, André& Neri 1998; Sadavoy primarily within the dense gas in molecular clouds. For et al. 2010; see, however, Reid et al. 2010 for counter- example, comparisons of core locations against extinction arguments). Further progress has been difficult because maps revealed that cores were found preferentially towards we have been generally blind to cloud structure on in- locations above a specific high extinction threshold (AV termediate scales, and thus unable to see well how cores = 5-8), suggesting the existence of a relationship between condense out of their parent clouds. high column densities and the ability of small-scale struc- In the last few years, the ESA Herschel Space Observa- ture to condense out of clouds (Johnstone, Di Francesco tory has proven to be a game-changer. As part of the & Kirk 2004; Kirk et al. 2006). More recently, Lada et Herschel/SPIRE instrument team, I have been fortunate al. (2010) found a linear correlation in log space between to be involved in key projects that are greatly improving the numbers of young stellar objects (YSOs) in nearby our understanding of how cores condense out of clouds, the clouds and the amounts of material in those clouds at Gould Belt Survey (GBS; PI: Ph. André) and the Herschel high visual extinction (AV > 10). In addition, Wu et OB Young Star Survey (HOBYS; PI: F. Motte). These al. (2005) found a linear correlation over 10 decades in log projects used Herschel’s two mapping instruments, SPIRE space between the infrared luminosity from young stars and PACS, to acquire high-resolution (8-35′′ FWHM) im- and the luminosity of the HCN 1-0 molecular transition ages of far-infrared and submillimetre continuum emission from dense gas. These results imply that the question across ∼30 molecular clouds within 3 kpc, with map sizes of what physically promotes star formation is related to covering ∼1-30 square degrees. These data improved on the question what kinds of structures in molecular previous ground-based maps in several ways. First, Her- clouds arise to enable dense gas to accumulate? schel could map emission over a much wider range of (in- The short answer appears to be “filamentary” (my dear termediate) spatial scales than previously possible because Watson). In this Perspective, I briefly describe how recent atmospheric emission subtraction was not needed. Second, observations, especially those from Herschel, are showing SPIRE and PACS together obtained data simultaneously the roles molecular cloud filaments play in star formation. at 70 µm, 160 µm, 250 µm, 350 µm, and 500 µm, wave- Previously, molecular cloud structure was traced by large- lengths that straddle the spectral peaks of optically thin scale maps of either the emission of CO excited at the emission emitted by cold dust and allow for high mass mean densities of clouds or the visual extinction of back- sensitivity. (Indeed, such wavelengths have zero atmo- ground stars by dust intermixed with the gas. Such cloud spheric transmission and so cannot be observed from the maps were generally low resolution (e.g., 1-5′ FWHM; e.g., ground.) Third, the SPIRE+PACS wavelength coverage Ridge et al. 2006; Cambrésy 1999), making it difficult can probe dust temperatures, significantly improving line- to see cloud structure on intermediate-scales or smaller. of-sight column density estimates.

10 Figure 1: Composite map of SPIRE+PACS data of the far-infrared/submillimetre continuum emission from the Perseus molecular cloud, where blue indicates 160 µm emission, green indicates 250 µm emission, and blue indicates 500 µm emission (from Sadavoy et al. 2012).

Figure 2: Column density maps of the Polaris Flare (left) and the Aquila Rift obtained from SPIRE+PACS data filtered to show only intermediate scales. Filamentary structures are seen in each map. Each image has been scaled differently to the critical mass per unit length at T = 10 K, where white on the left corresponds to 0.5 × the critical value and white on the right corresponds to that value. No filament in Polaris exceeds the critical value and no star- forming cores (blue) or YSOs (green) are seen. On the other hand, in Aquila such objects are seen, predominantly in supercritical filaments (from Andréet al. 2010).

11 Figure 1 shows an example of one spectacular map from The Aquila and Polaris maps also revealed how important the GBS, the Perseus molecular cloud at 235 pc (see Sa- filaments can be to star formation. Assuming a typical davoy et al. 2012). Even this single image shows incredi- width of ∼104 AU = 0.05 pc, the column densities in Fig- ble amounts of never-before-seen detail of cloud structure. ure 2 can be recast as masses per unit length. Further While previous, low-resolution extinction maps suggested analysis revealed an astonishing correspondence in Aquila a quiescent Perseus, the numerous sinuous tendrils and between small-scale cores that are arguably gravitation- wispy features shown by Herschel to pervade the entire ally bound (and hence more likely to be star-forming), the cloud suggest a far more dynamic evolution. Moreover, youngest YSOs, and filaments exceeding a critical mass 2 −1 unlike previous maps, the SPIRE+PACS data reveal ob- per unit length , Mline =2cs/G ≈ 16 M⊙ pc atT=10 vious significant temperature variations across the cloud. K. This critical mass per unit length was previously iden- For example, eastern Perseus exhibits more shorter wave- tified by Inutsuka & Miyama (1997) as the point where length emission than western Perseus, indicating warmer isothermal cylinders become unstable. Indeed, the colors temperatures. in Figure 2 (right) are scaled such that white corresponds Even the very first detailed analyses of Herschel contin- to masses per unit length equal to or exceeding the critical uum data of molecular clouds revealed significant insights value for T = 10 K. Hence, stars appear to form more of- into star formation in nearby clouds. For a special issue of ten in supercritical filaments where star-forming cores can Astronomy & Astrophysics that highlighted the first Her- form more efficiently through fragmentation. In the Po- schel SPIRE and PACS results, HOBYS identified for the laris Flare, however, no filaments that exceed the critical first time the population of compact cores (and clumps, threshold of stability are found; the colors in Figure 2 (left) i.e., collections of cores from which clusters form) within are actually scaled such that white corresponds to masses the Rosette molecular cloud, at a distance of 1.6 kpc (Di per unit length of half the critical value. With no crit- Francesco et al. 2010; see also Motte et al. 2010; Schneider ical or supercritical filaments in Polaris, correspondingly et al. 2010; Hennemann et al. 2010). A comparison with no star-forming cores or young stellar objects are found. Spitzer infrared data revealed that 371 of these compact Note that this connection neatly explains the threshold objects were starless while 102 were coincident with young seen in earlier studies between extinction and the devel- stellar objects. The resulting mass spectrum of these ob- opment of small-scale structure in clouds, i.e., the typ- jects was found to have a shallow slope at higher masses ically bound cores detected previously by ground-based similar to those seen from CO data cubes in the Rosette instruments were seen preferentially above an extinction and other clouds. This result suggested that the differ- threshold because the corresponding column densities at ences seen between the steeper Salpeter IMF-like slopes those locations exceed the critical value for filament sta- of mass distributions obtained from continuum maps of bility. (The Aquila data also had profound implications closer clouds and the shallower slopes of mass distributions about the CMF and IMF connection. The population of ∼ × obtained from line maps are due to resolution differences. bound cores detected in Aquila was 6 larger than previous studies of any other cloud, and its CMF was found In the same special A&A issue, the GBS revealed the to resemble the IMF more robustly than seen before. For structure of continuum emission on intermediate scales example, the slope of its high-mass tail is -1.5 ± 0.2 while within two nearby clouds, the Aquila Rift and Polaris that of the Salpeter IMF is -1.35.) Flare (see Andréet al. 2010; Könyves et al. 2010, Ward- Thompson et al. 2010, and Miville-Deschênes et al. 2010). The physical implication of filaments is that they provide These clouds differ in that the former has relatively high a very efficient means for dense gas to accumulate within column densities and is actively forming stars but the lat- turbulent molecular clouds and produce star-forming cores. ter has relatively low column densities and is not forming Dense gas accumulation directly into cores via internal tur- stars. Figure 2 shows spatially decomposed column den- bulent motions within clouds is inefficient, given the intrin- sity maps of each cloud from Andréet al. 2010. Strikingly, sic difficulty of such motions to push material directly into each cloud is seen to be similarly rife on intermediate scales core-like points in 3D volumes. Turbulent motions, how- with long filamentary structures of 1-5 pc length. The fact ever, may easily compress material into sheets, i.e., planar that filaments were found in either cloud suggests that condensations of significant extent. Such sheets, however, their appearance is not related to star formation activity are extremely resistant to collapse though, since internal (e.g., due to feedback) but is instead the result of global pressure gradients can always become large enough to halt processes intrinsic to the clouds themselves. Though fila- further compression into cores (see Miyama et al. 1987). ments have been seen in star-forming clouds for decades, Indeed, sheets may fragment more easily into filamentary the known examples have been the most prominent. Her- structures (Miyama et al. 1987). Spherical configurations schel has revealed filaments to be actually omnipresent are also problematic, in particular for producing popula- within molecular clouds. tions of cores. For example, global collapse has the fastest growth rate of perturbations within spheres, promoting

12 the rise of a single central concentration (Larson 1969; Shu radial density structure to be shallower than that expected 1977). Moreover, fragmentation is suppressed and the lo- from an isothermal cylinder (cf. Ostriker 1964; Arzouma- cal collapse of other finite perturbations is overwhelmed nian et al. 2013; Palmeirim et al. 2013). Indeed, close (Tohline 1982). On the other hand, filaments can remain examination of the dust temperatures of this filament re- stable until a critical threshold is reached, allowing small- vealed they have colder interiors, as may be expected from scale perturbations to grow significantly via internal mass increased shielding from the ISRF by higher column den- flows until global collapse is possible (see Pon et al. 2011, sities. Nevertheless, the radial temperature profile was 2012; Toaláet al. 2012). The detection by Herschel of per- fitted well using a polytropic equation of state, P ∝ ργ , vasive filamentary structure within molecular clouds and with γ = 0.97 ± 0.01. Moreover, streamers perpendicu- the very close connection of filaments to star formation lar to B211 were identified as subcritical filaments likely are welcome observational confirmations of these ideas. feeding further mass onto B211 itself. Finally, HOBYS noted that infrared clusters and the highest-mass clumps in the Rosette molecular cloud and Cygnus X (DR 21) were coincident with intersections of filaments (Schneider et al. 2012; Hennemann et al. 2012; Hill et al. 2011). These results imply that clusters and perhaps high-mass star formation itself occur when filaments intersect, providing multiple avenues for increased mass accumulation in small volumes, as suggested by Myers (2011). The near- term goal of both GBS and HOBYS is to provide enhanced data products and source catalogues for each cloud to the community in a series of papers starting in early 2014. As part of the GBS and HOBYS surveys, our group in Victoria has used survey data to probe further the relationship between dense gas and star-forming cores. For example, the recently completed dissertation of my stu- dent Sarah Sadavoy focused on SPIRE+PACS data of the nearby Perseus molecular cloud (see Figure 1). Our first Figure 3: (upper left) Column density map of the Perseus GBS investigation involved a study of one ∼100 M⊙ clump B1-E clump obtained from SPIRE+PACS data. The lo- in central Perseus called B1-E, where extinction maps sug- cations of the nine highest column peaks are indicated by gested that core/star formation should have occurred but open numbered circles. (Right, moving counter-clockwise) where no compact cores or YSOs had been detected pre- NH3 (1,1) spectra obtained at the positions of four col- viously (Sadavoy et al. 2012). As shown in Figure 3, we umn density peaks with the GBT, indicating the presence found that B1-E was indeed populated by dense gas, in of dense gas. At location 2, the line is detected strongly the form of a collection of ∼10 starless cores arranged in with a narrow width indicating low turbulent motions and a ring-like pattern. Using NH3 data obtained from the a high likelihood of the associated core being gravitation- GBT to probe internal velocities of these cores, we found ally bound (from Sadavoy et al. 2012). only one core, B1-E2, is arguably bound. B1-E is thus a rare, pristine environment where a first generation of cores Since 2010, the GBS and HOBYS projects have moved is forming purely due to fragmentation, and the process forward in exploring how filamentary structure relates to can be viewed without any distortions from the influence star formation. As Herschel continued to acquire data, the of already-formed stars. Indeed, star formation may be survey teams produced notable new results from the maps. delayed in B1-E due to locally strong magnetic fields; we For example, the GBS made the surprising discovery that are following up this possibility through polarimetric ob- filaments in several clouds have a narrow width distribu- servations. In addition, we are continuing to explore the tion sharply peaked at ∼0.1 pc, despite two decades of star-forming activities of the major clumps of Perseus, us- variation in central column densities (Arzoumanian et al. ing Spitzer and Herschel data to recover the protostellar 2011). The similar widths may be the result of the tur- and core populations respectively (Sadavoy et al. 2014, in bulent origins of filaments, as these may be related to the preparation). length scales of shocks produced by colliding turbulent For HOBYS, my recent postdoctoral fellow, Cassandra flows within clouds, but the possibility of a similar scale as Fallscheer, led an examination of the SPIRE+PACS data sheets fragment into filaments merits study. Furthermore, of NGC 7538. These data demonstrate how external events the GBS investigated the internal structure of the sizeable may also shape clouds and form filamentary structures. supercritical filament L1495/B211-3 in Taurus, finding its

13 β For example, Figure 4 shows a composite image of this in nearby clouds has a form of κν ∝ ν with constant β 2.7 kpc distant cloud where a prominent ∼10 pc wide ring = 2, as expected from ISM dust. Nevertheless, β may is seen north of the G111 region. The extraordinary ring be expected to change if dust grain growth occurs in cold appears empty in both continuum emission and CO (3-2) dense environments like cores. Since the masses measured emission from the cloud, suggesting material within it has from cores using their submillimetre fluxes depend on the been cleared out by some powerful previous event, forming value of κν assumed, it is important to know β to reason- the surrounding filamentary structure. No “smoking gun” able accuracy. Using data of the Perseus B1 clump, we has been identified within the ring, however. In addition, showed that β indeed changes as a result of grain growth, we identified 13 starless, cold condensations in NGC 7538 and core masses could differ from those obtained from Her- with masses >40 M⊙ that merit further examination as schel data alone by up to 30% (Sadavoy et al. 2013). Given possible sites of future star formation. the relatively small number of cores in B1, the impact of β Our Victoria group has also worked to expand on the Her- variations on the larger CMF of Perseus is not yet known; schel results using the highly complementary data from follow-up work on a larger number of clumps in Perseus is the JCMT Gould Belt Survey (JGBS), a UK-Canada- on-going (Chen et al. 2014, in preparation). Netherlands key project to obtain sensitive maps of high Note that almost all the above work has involved contin- column density areas in nearby clouds using the SCUBA-2 uum data and the kinematics of filaments and cores are and HARP instruments on the James Clerk Maxwell Tele- not recoverable from such data. Studies of filament kine- scope (JCMT; see Ward-Thompson et al. 2007). These matics are extremely important, however, if anything to data are at a similar resolution to those from Herschel see if the filaments and cores are moving in line with ex- (∼15′′) at 850 µm), but are further down the Rayleigh- pectations. Fortunately, several recent studies have begun Jeans tail of the cold dust spectrum than probed by Her- to reveal the kinematics of some filament networks. For schel. Therefore, these data allow us to constrain the example, Hacar et al. (2013) recently probed the velocity optical characteristics of the emitting dust much better structure of the ∼10 pc-long L1495/B213 filament in C18O + than possible with Herschel data alone. For example, the 1-0 and N2H 1-0, finding 35 filamentary components of GBS and HOBYS teams have assumed the dust opacity ∼0.5 pc length, with several overlapping on the sky but at distinctly different velocities. Since these individual “fibers” appear to be near the stability point for cylinders, some of the supercritical filaments identified with Herschel may actually be composed of bundles of stable fibers seen along the line-of-sight. Of course, direct investigations of filaments in other clouds are needed. Filament kinematics were also recently studied by Arzou- manian et al. (2013) who examined the line widths of 18 + C O (2-1) and N2H (1-0) emission from 44 filaments in single pointings toward IC 5146, Polaris, and Aquila. They found that subcritical filaments exhibited lines with widths typical of trans-sonic motions (where thermal and turbulent motions are of similar magnitude), as might be expected from Larson’s Laws at the ∼0.1 pc scale probed (see Larson 1981). On the other hand, supercritical filaments exhibited lines with widths increasing roughly with the square root of the central column densities of the filaments. Arzoumanian et al. did not interpret these increased line widths in terms of increased turbulent motions but instead suggested they were the result of the conversion into kinetic energy of potential energy of ad- jacent material accreting onto the filaments. Moreover,

′ ′ they argued that subsequent evolution of the filaments is Figure 4: Composite image of an approximately 50 × 50 quasi-virial (i.e., near equilibrium), in part to account also portion of NGC 7538. The wavebands included are PACS for constant filament widths previously observed. 70 µm (blue), PACS 160 µm (green), and SPIRE 250 µm (red). The eastern half of the image is dominated by Other recent kinematic studies have focused on the re- a prominent ring-like feature of uncertain origin (from lationship between filaments and clusters. For example, Fallscheer et al. 2013). Schneider et al. (2010) studied the DR 21 region in a va-

14 riety of lines, finding 13CO (1-0) and H13CO+ (1-0) line Hennemann, M., Motte, F., et al. 2010, A&A, 518, L84 emission obtained from the IRAM 30 m Telescope that in- Hill, T., Motte, F., Didelon, P. et al. 2011, A&A, 533, 94 dicated the intersecting filaments in that region are indeed Inutsuka, S., & Miyama, S.M. 1997, ApJ, 480, 681 kinematically similar. Moreover, they roughly estimated a Johnstone, D., Di Francesco, J., et al. 2004, ApJ, 611, L45 mass flow rate along the most massive filament of 2 × 10−3 Kirk, H. M., Johnstone, D., et al. ApJ, 2006, 646, 1009 −1 6 M⊙ yr , which over its dynamical timescale of 2 × 10 Kirk, H. M., Myers, P. C., et al. 2013, ApJ, 766, 115 yr could add as much as 80% more mass to the most mas- Könyves, V., André, Ph., et al. 2010, A&A, 518, L106 sive clump in the region. Other examples include studies Lada, C.J., Lombardi, M, & Alves, J. 2010, ApJ, 724, 687 of the filaments associated with the Serpens South clus- Larson, R. B., 1969, MNRAS, 145, 271 ter by Kirk et al. (2013) and Friesen et al. (2013). In the Larson, R.B., 1981, MNRAS, 194, 809 + former paper, Kirk et al. used N2H (1-0) and HNC (1-0) Miville-Deschênes, M.-A., et al. 2010, A&A, 518, L104 emission to trace mass flows along and onto the southern Miyama, S. M. 1987, Prog. Theor. Phys., 78, 1273 half of the dominant filament, respectively, estimating a Motte, F., André, Ph., & Neri, R. 1998, A&A, 365, 440 −4 −1 total mass flow rate of 1.5 × 10 M⊙ yr , an amount Motte, F., Zavagno, A., et al. 2010, A&A, 518, L77 on the same order as the current star-formation rate of the Myers, P. C. 2011, ApJ, 735, 82 Serpens South cluster itself. In the latter paper, Friesen Ostriker, J. 1964, ApJ, 140, 1056 et al. used HC7N (21-20) emission obtained with the GBT Palmeirim, P., André, Ph., Kirk, J., et al. 2013, A&A, 550, −5 −1 to trace minimum accretion rates of 5 × 10 M⊙ yr A38 in the northern half of the filament. These studies clearly Pon, A., Johnstone, D., & Heitsch, F. 2011, ApJ, 740, 88 show promise, yet more are certainly needed. Indeed, the Pon, A., Toalá, J. A., et al. 2012, ApJ, 756, 145 HARP data obtained by the JGBS will be used to probe Reid, M. A., Wadsley, J., Petitclerc, N., et al. 2010, ApJ, further the kinematics of filaments in nearby clouds. 719, 561 In summary, Herschel has provided new insights into how Ridge, N. A., Di Francesco, J.,. Kirk, H., et al. 2006, AJ, dense gas arises in molecular clouds. Filaments, likely 131, 2921 produced mostly by turbulent fragmentation, appear to Sadavoy, S., Di Francesco, J., et al. 2014, in preparation be important intermediate-scale structures that funnel gas Sadavoy, S., Di Francesco, J., et al. 2013, ApJ, 767, 126 from clouds to cores. At high enough column densities, fil- Sadavoy, S., Di Francesco, J., et al. 2012, A&A, 540, 10 aments can produce bound cores that in turn likely form Sadavoy, S., Di Francesco, J., et al. 2010, ApJ, 710, 1247 stars. Note that we have only scratched the surface of Schneider, N., Csengeri, T., et al. 2012, A&A, 540, L11 the incredibly rich Herschel datasets. Further kinematic Schneider, N., Motte, F., et al. 2010, A&A, 518, L83 follow-up of filamentary structures in nearby clouds will Shu, F. H., 1977, ApJ, 214, 488 be key to progress in the near future. Readers interested Toalá, J. A., et al. 2012, ApJ, 744, 190 in further summary of the topics discussed here are di- Tohline, J. E. 1982, Fund. of Cos. Phys., 8, 1 rected to a comprehensive review by Andréet al. (2014, Ward-Thompson, D. Di Francesco, J., et al. 2007, PASP, submitted) to be published in the forthcoming Protostars 119, 855 and Planets VI monograph. Ward-Thompson, D., Kirk, J. M., et al. 2010, A&A, 518, L92 Acknowledgements: We thank Helen Kirk for a careful Wu, J., Evans, N. J., II, Gao, Y., et al. 2005, ApJ, 635, reading of this article prior to submission. Also, we apol- L173 ogize to Dan Watson for any confusion regarding the title of this article. References: André, Ph., Menshchikov, A., et al. 2010, A&A, 518, L102 Arzoumanian, D., Andr, Ph., et al. 2011, A&A, 529, L6 Cambrésy, L. 1999, A&A, 345, 965 Di Francesco, J., Sadavoy, S., et al. 2010, A&A, 518, L91 Fallscheer, C., Reid, M., et al. 2013, ApJ, 773, 102 Friesen, R. K., Di Francesco, J., et al. 2009, ApJ, 697, 1457 Friesen, R. K., Medeiros, L., et al. 2013, MNRAS, in press Goodman, A., et al. 1998, ApJ, 504, 223 Hacar, A., Tafalla, M., Kauffmann, J., et al. 2013, A&A, 554, 55 Hennemann, M., Motte, F., et al. 2012, A&A, 543, L23

15 Abstracts of recently accepted papers

Influence of the C/O ratio on titanium and vanadium oxides in protoplanetary disks M. Ali-Dib1, O. Mousis1, G.S. Pekmezci2, J.I. Lunine3, N. Madhusudhan4 and J.-M. Petit1 1 Institut UTINAM, CNRS-UMR 6213, Observatoire de Besancon, BP 1615, 25010 Besancon Cedex, France 2 Dipartimento di Astronomia, Universita di Roma Tor Vergata, Via della Ricerca Scientica 1, 00133 Roma, Italy 3 Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853, USA 4 Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06511, USA E-mail contact: mdib at obs-besancon.fr Context. The observation of carbon-rich disks have motivated several studies questioning the influence of the C/O ratio on their gas phase composition in order to establish the connection between the metallicity of hot-Jupiters and that of their parent stars. Aims. We to propose a method that allows the characterization of the adopted C/O ratio in protoplanetary disks independently from the determination of the host star composition. Titanium and vanadium chemistries are investigated because they are strong optical absorbers and also because their oxides are known to be sensitive to the C/O ratio in some exoplanet atmospheres. Methods. We use a commercial package based on the Gibbs energy minimization technique to compute the titanium and vanadium equilibrium chemistries in protoplanetary disks for C/O ratios ranging from 0.05 to 10. Our calculations are performed for pressures ranging from 1 × 10−6 to 1 × 10−2 bar, and for temperatures ranging from 50 to 2000 K. Results. We find that the vanadium nitride/vanadium oxide and titanium hydride/titanium oxide gas phase ratios strongly depend on the C/O ratio in the hot parts of disks (T > 1000 K). Our calculations suggest that, in these regions, these ratios can be used as tracers of the C/O value in protoplanetary disks. Accepted by A&A http://arxiv.org/pdf/1311.2916

Structures in the protoplanetary disk of HD142527 seen in polarized scattered light Henning Avenhaus1, Sascha P. Quanz1, Hans Martin Schmid1, Michael R. Meyer1, Antonio Garuﬁ1, Sebastian Wolf2 and Carsten Dominik3 1 ETH Zurich, Institute for Astronomy, Wolfgang-Pauli- Strasse 27, 8093 Zurich, Switzerland 2 University of Kiel, Institute of Theoretical Physics and As- trophysics, Leibnizstrasse 15, 24098 Kiel, Germany 3 University of Amsterdam, Astronomical Institute Anton Pannekoek, Postbus 94249, 1090 GE Amsterdam, Nether- lands E-mail contact: havenhaus at phys.ethz.ch

We present H- and Ks-band polarized diﬀerential images (PDI) of the Herbig Ae/Be star HD142527, revealing its optically thick outer disk and the nearly empty gap. The very small inner working angle (∼0.1”) and high resolution achievable with an 8m-class telescope, together with a careful polarimetric calibration strategy, allow us to achieve images that surpass the quality of previous scattered light images. Previously known substructures are resolved more clearly and new structures are seen. Speciﬁcally, we are able to resolve 1) half a dozen spiral structures in the disk, including previously known outer-disk spirals as well as new spiral arms and arcs close to the inner rim of the disk; 2) peculiar holes in the polarized surface brightness at position angles of ∼0◦ and ∼160◦; 3) the inner rim on the eastern side of the disk; 4) the gap between the outer and inner disk, ranging from the inner working angle of 0.1” out to between 0.7 and 1.0”, which is nearly devoid of dust. We then use a Markov-chain Monte-Carlo algorithm to determine several structural parameters of the disk, using very simple assumptions, including its inclination, eccentricity, and the scale height of the inner rim. We compare our results to previous work on this object, and try to produce a consistent picture of the system and its transition disk.

16 Accepted by ApJ http://arxiv.org/pdf/1311.7088

Radio detection of the young binary HD 160934 R. Azulay1, J.C. Guirado1,2, J.M. Marcaide1, I. Mart´ı-Vidal3, and B. Arroyo-Torres1 1 Departamento de Astronom´ıay Astrofsica, Universidad de Valencia, E-46100 Burjassot, Valencia, Spain 2 Observatorio Astron´omico, Universidad de Valencia, E-46980 Paterna, Valencia, Spain 3 Onsala Space Observatory, Chalmers University of Technology, Onsala, Sweden E-mail contact: rebecca.azulay at uv.es Precise determination of dynamical masses of pre-main-sequence (PMS) stars is essential to calibrate stellar evolution models that are widely used to derive theoretical masses of young low-mass objects. Binary stars in young, nearby loose associations are particularly good candidates for this calibration since all members share a common age. Interestingly, some of these young binaries present a persistent and compact radio emission, which makes them excellent targets for astrometric VLBI studies. We aim to monitor the orbital motion of the binary system HD 160934, a member of the AB Doradus moving group. We observed HD 160934 with the Very Large Array and the European VLBI Network at 8.4 and 5 GHz, respectively. The orbital information derived from these observations was analyzed along with previously reported orbital measurements. We show that the two components of the binary, HD 160934 A and HD 160934 c, display compact radio emission at VLBI scales, providing precise information on the relative orbit. Revised orbital elements were estimated. Future VLBI monitoring of this pair should determine precise model-independent mass estimates for the A and c components, which will serve as calibration tests for PMS evolutionary models. Accepted by A&A http://arxiv.org/pdf/1311.5443

On the Outer Edges of Protoplanetary Dust Disks T. Birnstiel1 and S. M. Andrews1 1 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA E-mail contact: tbirnstiel at cfa.harvard.edu The expectation that aerodynamic drag will force the solids in a gas-rich protoplanetary disk to spiral in toward the host star on short timescales is one of the fundamental problems in planet formation theory. The nominal efficiency of this radial drift process is in conflict with observations, suggesting that an empirical calibration of solid transport mechanisms in a disk is highly desirable. However, the fact that both radial drift and grain growth produce a similar particle size segregation in a disk (such that larger particles are preferentially concentrated closer to the star) makes it difficult to disentangle a clear signature of drift alone. We highlight a new approach, by showing that radial drift leaves a distinctive “fingerprint” in the dust surface density profile that is directly accessible to current observational facilities. Using an analytical framework for dust evolution, we demonstrate that the combined effects of drift and (viscous) gas drag naturally produce a sharp outer edge in the dust distribution (or, equivalently, a sharp decrease in the dust-to-gas mass ratio). This edge feature forms during the earliest phase in the evolution of disk solids, before grain growth in the outer disk has made much progress, and is preserved over longer timescales when both growth and transport effects are more substantial. The key features of these analytical models are reproduced in detailed numerical simulations, and are qualitatively consistent with recent millimeter-wave observations that find gas/dust size discrepancies and steep declines in dust continuum emission in the outer regions of protoplanetary disks. Accepted by the Astrophysical Journal http://arxiv.org/pdf/1311.5222v1

High-Resolution Near Infrared Spectroscopy of HD 100546: II. Analysis of variable rovibrational CO emission lines Sean D. Brittain1, Joan R. Najita2, John S. Carr3, Joseph Liskowsky1, Matthew R. Troutman4, and Greg W. Doppmann5 1 Department of Physics & Astronomy, 118 Kinard Laboratory, Clemson University, Clemson, SC 29634, USA

17 2 National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ 85719, USA 3 Naval Research Laboratory, Code 7211, Washington, DC 20375, USA 4 Department of Physics & Astronomy, University of Missouri - St. Louis, St. Louis, MO 63121, USA 5 W.M. Keck Observatory, 65-1120 Mamalahoa Hwy, Kamuela, HI 96743, USA E-mail contact: sbritt at clemson.edu We present observations of rovibrational CO in HD 100546 from four epochs spanning January 2003 through December 2010. We show that the equivalent widths of the CO lines vary during this time period with the v=1–0 CO lines brightening more than the UV fluoresced lines from the higher vibrational states. While the spectroastrometric signal of the hot band lines remains constant during this period, the spectroastrometric signal of the v=1–0 lines varies substantially. At all epochs, the spectroastrometric signals of the UV fluoresced lines are consistent with the signal one would expect from gas in an axisymmetric disk. In 2003, the spectroastrometric signal of the v=1–0 P26 line was symmetric and consistent with emission from an axisymmetric disk. However, in 2006, there was no spatial offset of the signal detected on the red side of the profile, and in 2010, the spectroastrometric offset was yet more strongly reduced toward zero velocity. A model is presented that can explain the evolution of the equivalent width of the v=1–0 P26 line and its spectroastrometric signal by adding to the system a compact source of CO emission that orbits the star near the inner edge of the disk. We hypothesize that such emission may arise from a circumplanetary disk orbiting a gas giant planet near the inner edge of the circumstellar disk. We discuss how this idea can be tested observationally and be distinguished from an alternative interpretation of random fluctuations in the disk emission. Accepted by ApJ http://arxiv.org/pdf/1311.5647

The CHESS survey of the L1157-B1 bow-shock: high and low excitation water vapor G. Busquet1, B. Lefloch2,3, M. Benedettini1, C. Ceccarelli2, C. Codella4, S. Cabrit5, B. Nisini6, S. Viti7, A. I. Gómez-Ruiz4, A. Gusdorf8, A. M. di Giorgio1 and L. Wiesenfeld2 1 INAF - Istituto di Astrofisica e Planetologia Spaziali. Via del Fosso del Cavaliere 100, I-00133 Roma, Italy 2 UJF-Grenoble 1 / CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), UMR 5274, Greno- ble F-38041, France 3 Centro de Astrobiologia, CSIC-INTA, Carretera de Torrejón a Ajalvir, km 4, Torrejón de Ardoz, E-28850 Madrid, Spain 4 INAF, Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze, Italy 5 Observatoire de Paris, LERMA, UMR 8112 du CNRS, ENS, UPMC, UCP, 61 Av. de l’Observatoire, F-75014 Paris, France 6 INAF-Osservatorio Astronomico di Roma, Via di Frascati 33, I-00040 Monte Porzio Catone, Italy 7 Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK 8 LERMA, UMR 8112 du CNRS, Observatoire de Paris, Ecole´ Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France E-mail contact: gemma.busquet at iaps.inaf.it Context. Molecular outflows powered by young protostars strongly affect the kinematics and chemistry of the natal molecular cloud through strong shocks resulting in substantial modifications of the abundance of several species. In particular, water is a powerful tracer of shocked material due its sensitivity to both physical conditions and chemical processes. Aims. As part of the “Chemical Herschel Surveys of Star forming regions” (CHESS) guaranteed time key program, we aim at investigating the physical and chemical conditions of H2O in the brightest shock region B1 of the L1157 molecular outflow. Methods. We observed several ortho- and para-H2O transitions using HIFI and PACS instruments on board Herschel toward L1157-B1, providing a detailed picture of the kinematics and spatial distribution of the gas. We performed a Large Velocity Gradient (LVG) analysis to derive the physical conditions of H2O shocked material, and ultimately obtain its abundance. Results. We detected 13 H2O lines with both instruments probing a wide range of excitation conditions. This is the largest data set of water lines observed in a protostellar shock that provide both the kinematics and the spatial information of the emitting gas. PACS maps reveal that H2O traces weak and extended emission associated with the

18 ′′ outflow identified also with HIFI in the o-H2O line at 556.9 GHz, and a compact (∼10 ) bright, higher-excitation region. The LVG analysis of H2O lines in the bow-shock show the presence of two gas components with different 6 −3 excitation conditions: a warm (Tkin≃200-300 K) and dense (n(H2)≃(1–3)×10 cm ) component with an assumed ′′ ′′ ′′ 3−4 −3 extent of 10 and a compact (∼2 -5 ) and hot, tenuous (Tkin≃900-1400 K, n(H2)≃10 cm ) gas component, which is needed to account for the line fluxes of high Eu transitions. The fractional abundance of the warm and hot H2O gas components is estimated to be (0.7–2)×10−6 and (1–3)×10−4, respectively. Finally, we identified an additional component in absorption in the HIFI spectra of H2O lines connecting with the ground state level. This absorption probably arises from the photodesorption of icy mantles of a water-enriched layer at the edges of the cloud, driven by the external UV illumination of the interstellar radiation field. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1311.2840

Probing interstellar extinction near the 30 Doradus nebula with red giant stars Guido De Marchi1, Nino Panagia2,3,4, Léo Girardi5 1 European Space Agency, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands 2 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 3 INAF–NA, Osservatorio Astronomico di Capodimonte, Salita Moiariello, 16 80131 Naples, Italy 4 Supernova Limited, OYV #131, Northsound Rd., Virgin Gorda VG 1150, Virgin Islands, UK 5 INAF–PD, Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, 35122 Padua, Italy E-mail contact: gdemarchi at rssd.esa.int We have studied the interstellar extinction in a field of ∼ 3′× 3′ located about 6′ SW of 30Doradus in the Large Magellanic Cloud (LMC). Hubble Space Telescope observations in the U, B, V , I and Hα bands reveal patchy extinction in this field. The colour–magnitude diagram (CMD) shows an elongated stellar sequence, almost parallel to the main sequence (MS), which is in reality made up of stars of the red giant clump (RC) spread across the CMD by the uneven levels of extinction in this region. Since these objects are all at the same distance from us and share very similar physical properties, we can derive quantitatively both the extinction law in the range 3 000 − 8000A˚ and the absolute extinction towards about 100 objects, setting statistically significant constraints on the dust grains properties in this area. We find an extinction curve considerably flatter than the standard Galactic one and than those obtained before for the LMC. The derived value of RV =5.6 ± 0.3 implies that in this region larger grains dominate. Upper MS stars span a narrower range of E(B − V ) values than RC objects, at variance with what has been found elsewhere in the LMC. Accepted by MNRAS http://arxiv.org/pdf/1311.3659

Small vs large dust grains in transitional disks: do different cavity sizes indicate a planet? Antonio Garufi1, Sascha P. Quanz1, Henning Avenhaus1, Esther Buenzli2,3, Carsten Dominik4, Farzana Meru1, Michael R. Meyer1, Paola Pinilla5,6, Hans Martin Schmid1 and Sebastian Wolf7 1 Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland 2 Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721, USA 3 Max-Planck Institute for Astronomy, Knigstuhl 17, D-69117, Heidelberg, Germany 4 Sterrenkundig Instituut Anton Pannekoek, Science Park 904, 1098 XH Amsterdam, The Netherlands 5 Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany 6 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, the Netherlands 7 University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24098 Kiel, Germany E-mail contact: antonio.garufi at phys.ethz.ch Transitional disks represent a short stage of the evolution of circumstellar material. Studies of dust grains in these objects can provide pivotal information on the mechanisms of planet formation. Dissimilarities in the spatial distri-

19 bution of small (micron-size) and large (millimeter-size) dust grains have recently been pointed out. Constraints on the small dust grains can be obtained by imaging the distribution of scattered light at near-infrared wavelengths. We aim at resolving structures in the surface layer of transitional disks (with particular emphasis on the inner 10 - 50 AU), thus increasing the scarce sample of high resolution images of these objects. We obtained VLT/NACO near-IR high-resolution polarimetric differential imaging observations of SAO 206462 (HD135344B). This technique allows one to image the polarized scattered light from the disk without any occulting mask and to reach an inner working angle of 0.1”. A face-on disk is detected in H and Ks bands between 0.1” and 0.9”. No significant differences are seen between the H and Ks images. In addition to the spiral arms, these new data allow us to resolve for the first time an inner cavity for small dust grains. The cavity size (about 28 AU) is much smaller than what is inferred for large dust grains from (sub-)mm observations (39 to 50 AU). The interaction between the disk and potential orbiting companion(s) can explain both the spiral arm structure and the discrepant cavity sizes for small and large dust grains. One planet may be carving out the gas (and, thus, the small grains) at 28 AU, and generating a pressure bump at larger radii (39 AU), which holds back the large grains. We analytically estimate that, in this scenario, a single giant planet (with a mass between 5 and 15 Jupiter masses) at 17 to 20 AU from the star is consistent with the observed cavity sizes. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1311.4195

CoRoT 223992193: A new, low-mass, pre-main sequence eclipsing binary with evidence of a circumbinary disk E. Gillen1, S. Aigrain1, A. McQuillan1,2, J. Bouvier3, S. Hodgkin4, S.H. P. Alencar5, C. Terquem1, J. Southworth6, N.P. Gibson7, A. Cody8, M. Lendl9, M. Morales-Calderón10, F. Favata11, J. Stauer8, and G. Micela12 1 Sub-department of Astrophysics, Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK 2 School of Physics and Astronomy, Raymond and Beverly Sackler, Faculty of Exact Sciences, Tel Aviv University, 69978, Tel Aviv, Israel 3 UJF-Grenoble 1 / CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Greno- ble, F-38041, France 4 Institute of Astronomy, Madingley Road, Cambridge CB3 0HA 5 Departamento de F´ısica - ICEx - UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG, Brazil 6 Astrophysics Group, Keele University, Staordshire, ST5 5BG, UK 7 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany 8 Spitzer Science Center, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125, USA 9 Observatoire de Genève, Universitéde Genève, Chemin des maillettes 51, 1290 Sauverny, Switzerland 10 Centro de Astrobiolog´ıa(INTA-CSIC); ESAC Campus, P.O. Box 78, E-28691 Villanueva de la Canada, Spain 11 European Space Agency, 8-10 rue Mario Nikis, 75738 Paris Cedex 15, France 12 INAF Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134, Palermo, Italy E-mail contact: ed.gillen at astro.ox.ac.uk We present the discovery of CoRoT 223992193, a double-lined, detached eclipsing binary, comprising two pre-main sequence M dwarfs, discovered by the CoRoT space mission during a 23-day observation of the 3 Myr old NGC 2264 star-forming region. Using multi-epoch optical and near-IR follow-up spectroscopy with FLAMES on the Very Large Telescope and ISIS on the William Herschel Telescope we obtain a full orbital solution and derive the fundamental parameters of both stars by modelling the light curve and radial velocity data. The orbit is circular and has a period of 3.8745745±0.0000014 days. The masses and radii of the two stars are 0.67±0.01 and 0.495±0.007 M⊙ and 1.30±0.04 +0.04 and 1.11−0.05 R⊙, respectively. This system is a useful test of evolutionary models of young low-mass stars, as it lies in a region of parameter space where observational constraints are scarce; comparison with these models indicates an apparent age of ∼3.5–6 Myr. The systemic velocity is within 1σ of the cluster value which, along with the presence of lithium absorption, strongly indicates cluster membership. The CoRoT light curve also contains large-amplitude, rapidly evolving out-of-eclipse variations, which are difficult to explain using starspots alone. The system’s spectral energy distribution reveals a mid-infrared excess, which we model as thermal emission from a small amount of dust located in the inner cavity of a circumbinary disk. In turn, this opens up the possibility that some of the out-of-eclipse variability could be due to occultations of the central stars by material located at the inner edge or in the central

20 cavity of the circumbinary disk. Accepted by A&A http://arxiv.org/pdf/1311.3990

On the origin of the molecular outflows in IRAS 16293−2422 Josep M. Girart1, Robert Estalella2, Aina Palau1, JoséM. Torrelles1,2, Ramprasad Rao3 1 Institut de Ciències de l’Espai, (CSIC-IEEC), Campus UAB, Facultat de Ciències, C5p 2, 08193 Bellaterra, Catalonia, Spain 2 Departament d’Astronomia i Meteorologia, Institut de Ciències del Cosmos (UB-IEEC), Mart´ıi Franquès, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain 3 Institute of Astronomy and Astrophysics, Academia Sinica, 645 N. Aohoku Pl., Hilo, HI 96720, USA E-mail contact: girart at ice.cat We present CO 3–2, SiO 8–7, C34S 7–6, and 878 µm dust continuum subarcsecond angular resolution observations with the SMA toward IRAS 16293−2422 (I16293). The C34S emission traces well the 878 µm dust continuum, and shows clearly a smooth velocity gradient along the major axis of component I16293A. The CO shows emission at moderate high velocities arising from two bipolar outflows, which appear to be perpendicular with respect to each other. The high sensitivity and higher angular resolution of these observations allows to well pinpoint the origin of these two outflows at the center of component I16293A. Interestingly, the most compact outflow appears to point toward I16293B. Our data show that the previously reported monopolar blueshifted CO outflow associated with component I16293B seems to be part of the compact outflow arising from component I16293A. In addition, the SiO emission is also tracing this compact outflow: on one hand, the SiO emission appears to have a jet-like morphology along the southern redshifted lobe; on the other hand, the SiO emission associated with the blueshifted northern lobe traces a well defined arc on the border of component I16293B facing I16293A. The blueshifted CO lobe of the compact outflow splits in two lobes around the position of this SiO arc. All these leads us to propose that the compact outflow from component I16293A is impacting on the circumstellar gas around component I16293B, possibly being diverged as a consequence of the interaction. Accepted by ApJL http://arxiv.org/pdf/1311.4745

Probing the turbulent ambipolar diffusion scale in molecular clouds with spectroscopy Talayeh Hezareh1, Timea Csengeri1, Martin Houde2, Fabrice Herpin3 and Sylvain Bontemps4 1 Max Planck Institut fr Radioastronomy, Auf dem Hgel 69, D-,53121 Bonn, Germany 2 The University of Western Ontario, London, Ontario, N6A 3K7, Canada 3 Universit de Bordeaux, LAB, UMR 5804, F-33270, Floirac, France 4 CNRS, LAB, UMR 5804, F-33270, Floirac, France E-mail contact: thezareh at mpifr-bonn.mpg.de We estimate the turbulent ambipolar diffusion length-scale and magnetic field strength in the massive dense cores CygX-N03 and CygX-N53, located in the Cygnus-X star-forming region. The method we use requires comparing the velocity dispersions in the spectral line profiles of the coexistent ion and neutral pair H13CN and H13CO+ (J = 1-0) at different length-scales. We fit Kolmogorov-type power laws to the lower envelopes of the velocity dispersion spectra of the two species. This allows us to calculate the turbulent ambipolar diffusion scale, which in turn determines the plane-of-the-sky magnetic field strength. We find turbulent ambipolar diffusion length-scales of 3.8 +/- 0.1 and 21.2 +/- 0.4 mpc, and magnetic field strengths of 0.33 and 0.76 mG for CygX-N03 and CygX-N53, respectively. These magnetic field values have uncertainties of a factor of a few. Despite a lower signal-to-noise ratio of the data in CygX-N53 than in CygX-N03, and the caveat that its stronger field might stem in part from projection effects, the difference in field strengths suggests different fragmentation efficiencies of the two cores. Even though the quality of our data, obtained with the IRAM Plateau de Bure Interferometer, is somewhat inferior to previous single-dish data, we demonstrate that this method is suited also for observations at high spatial resolution. Accepted by MNRAS

21 Imaging the circumstellar environment of the young T Tauri star SU Aurigae S.V. Jeffers1,2, M. Min3,2, H. Canovas4, M. Rodenhuis2, and C.U. Keller2 1 Institut für Astrophysik, Georg-August-Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany 2 Leiden Observatory, P.O. Box 9513, NL-2300 RA Leiden, The Netherlands 3 Sterrenkundig Instituut Anton Pannekoek, Universiteit van Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands 4 Departamento de Fisica y Astronomia, Universidad de Valparaiso, Valpariso, Chile E-mail contact: Jeffers at astro.physik.uni-goettingen.de The circumstellar environments of classical T Tauri stars are challenging to directly image because of their high star- to-disk contrast ratio. One method to overcome this is by using imaging polarimetry where scattered and consequently polarised starlight from the star’s circumstellar disk can be separated from the unpolarised light of the central star. We present images of the circumstellar environment of SU Aur, a classical T Tauri star at the transition of T Tauri to Herbig stars. The images directly show that the disk extends out to ∼500 AU with an inclination angle of ∼50◦. Using interpretive models, we derived very small grains in the surface layers of its disk, with a very steep size- and surface-density distribution. Additionally, we resolved a large and extended nebulosity in our images that is most likely a remnant of the prenatal molecular cloud. The position angle of the disk, determined directly from our images, rules out a polar outflow or jet as the cause of this large-scale nebulosity. Accepted by A&A http://arxiv.org/pdf/1311.4832

Classical T Tauri stars: magnetic fields, coronae, and star-disc interactions C.P. Johnstone1, M. Jardine2, S.G. Gregory2, J.-F. Donati3 and G. Hussain4 1 University of Vienna, Department of Astronomy, Trkenschanzstrasse 17, 1180 Vienna, Austria 2 School of Physics and Astronomy, Universtiy of St Andrews, St Andrews, Scotland KY16 9SS 3 LATT-UMR 5572, CNRS & Univ. P. Sabatier, 14 Av. E. Belin, Toulouse, F-31400, France 4 ESO, Karl-Schwarzchild-Str. 2, D-85748 Garching, Germany E-mail contact: colin.johnstone at univie.ac.at The magnetic fields of young stars set their coronal properties and control their spin evolution via the star-disc interaction and outflows. Using 14 magnetic maps of 10 classical T Tauri stars (CTTSs) we investigate their closed X-ray emitting coronae, their open wind-bearing magnetic fields, and the geometry of magnetospheric accretion flows. The magnetic fields of all the CTTSs are multipolar. Stars with simpler (more dipolar) large-scale magnetic fields have stronger fields, are slower rotators, and have larger X-ray emitting coronae compared to stars with more complex large-scale magnetic fields. The field complexity controls the distribution of open and closed field regions across the stellar surface, and strongly influences the location and shapes of accretion hot spots. However, the higher order field components are of secondary importance in determining the total unsigned open magnetic flux, which depends mainly on the strength of the dipole component and the stellar surface area. Likewise, the dipole component alone provides an adequate approximation of the disc truncation radius. For some stars, the pressure of the hot coronal plasma dominates the stellar magnetic pressure and forces open the closed field inside the disc truncation radius. This is significant as accretion models generally assume that the magnetic field has a closed geometry out to the inner disc edge. Accepted by MNRAS http://arxiv.org/pdf/1310.8194

Far-infrared molecular lines from Low- to High-Mass Star Forming Regions observed with Herschel A. Karska1,2, F. Herpin3,4, S. Bruderer1, J.R. Goicoechea5, G.J. Herczeg6, E.F. van Dishoeck1,2, I. San Jos´e-Garc´ıa2, A. Contursi1, H. Feuchtgruber1, D. Fedele1, A. Baudry3,4, J. Braine3,4, L. Chavarr´ıa5, J. Cernicharo5, F.F.S. van der Tak7,8 and F. Wyrowski9

22 1 Max-Planck Institut für Extraterrestrische Physik (MPE), Giessenbachstr. 1, D-85748 Garching, Germany 2 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands 3 Universitéde Bordeaux, Observatoire Aquitain des Sciences de l’Univers, 2 rue de l’Observatoire, BP 89, F-33271 Floirac Cedex, France 4 CNRS, LAB, UMR 5804, F-33271 Floirac Cedex, France 5 Centro de Astrobiolog´ıa. Departamento de Astrof´ısica. CSIC-INTA. Carretera de Ajalvir, Km 4, Torrejón de Ardoz. 28850, Madrid, Spain 6 Kavli Institut for Astronomy and Astrophysics, Yi He Yuan Lu 5, HaiDian Qu, Peking University, Beijing, 100871, PR China 7 SRON Netherlands Institute for Space Research, PO Box 800, 9700 AV, Groningen, The Netherlands 8 Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV, Groningen, The Netherlands 9 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany E-mail contact: karska at mpe.mpg.de Aims. Our aim is to study the response of the gas to energetic processes associated with high-mass star formation and compare it with previously published studies on low- and intermediate-mass young stellar objects (YSOs) using the same methods. The quantified far-infrared line emission and absorption of CO, H2O, OH, and [O I] reveals the excitation and the relative contribution of different atomic and molecular species to the gas cooling budget. Methods. Herschel-PACS spectra covering 55–190 µm are analyzed for ten high-mass star forming regions of luminosi- 4 6 4 ties Lbol ∼ 10 − 10 L⊙ and various evolutionary stages at spatial scales of ∼ 10 AU. Radiative transfer models are used to determine the contribution of the quiescent envelope to the far-IR CO emission. Results. The close environments of high-mass protostars show strong far-infrared emission from molecules, atoms, and ions. Water is detected in all 10 objects even up to high excitation lines, often in absorption at the shorter wavelengths and in emission at the longer wavelengths. CO transitions from J = 14 − 13 up to typically 29 − 28 (Eu/kB ∼ 580 − 2400 K) show a single temperature component with a rotational temperature of Trot ∼300 K. Typical H2O excitation temperatures are Trot ∼250 K, while OH has Trot ∼80 K. Far-IR line cooling is dominated by CO (∼ 75%) and to a smaller extent by [O I] (∼20 %), which becomes more important for the most evolved sources. H2O is less important as a coolant for high-mass sources due to the fact that many lines are in absorption. Conclusions. Emission from the quiescent envelope is responsible for ∼ 45 − 85 % of the total CO luminosity in high-mass sources compared with only ∼10% for low-mass YSOs. The highest−J lines (Jup ≥20) originate most likely from shocks, based on the strong correlation of CO and H2O with physical parameters (Lbol, Menv) of the sources from low- to high-mass YSOs. Excitation of warm CO described by Trot ∼300 K is very similar for all mass regimes, whereas H2O temperatures are ∼100 K higher for high-mass sources compared with low-mass YSOs. The total far-IR cooling in lines correlates strongly with bolometric luminosity, consistent with previous studies restricted to low-mass YSOs. Molecular cooling (CO, H2O, and OH) is ∼4 times more important than cooling by oxygen atoms for all mass regimes. The total far-IR line luminosity is about 10−3 and 10−5 times lower than the dust luminosity for the low- and high-mass star forming regions, respectively. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1311.6644

Radial velocity variations in the young eruptive star EX Lup A.´ Kóspál1, M. Mohler-Fischer2, A. Sicilia-Aguilar3, P. Abrahám´ 4, M. Curé5, Th. Henning2, Cs. Kiss4, R. Launhardt2, A. Moór4, and A. Müller6 1 European Space Agency (ESA-ESTEC, SRE-S), PO Box 299, 2200 AG, Noordwijk, The Netherlands 2 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany 3 Departamento de F´ısica Teórica, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 C antoblanco, Madrid, Spain 4 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary 5 Departamento de F´ısica y Astronom´ıa, Facultad de Ciencias, Universidad de Valpara´ıso, A v. Gran Bretaña 1111, Casilla 5030, Valpara´ıso, Chile 6 European Southern Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile

23 E-mail contact: akospal at rssd.esa.int Context. EX Lup-type objects (EXors) are low-mass pre-main sequence objects characterized by optical and near- infrared outbursts attributed to highly enhanced accretion from the circumstellar disk onto the star. Aims. The trigger mechanism of EXor outbursts is still debated. One type of theory requires a close (sub)stellar companion that perturbs the inner part of the disk and triggers the onset of the enhanced accretion. Here, we study the radial velocity (RV) variations of EX Lup, the prototype of the EXor class, and test whether they can be related to a close companion. Methods. We conducted a five-year RV survey, collecting 54 observations with HARPS and FEROS. We analyzed the activity of EX Lup by checking the bisector, the equivalent width of the Ca 8662 A˚ line, the asymmetry of the CaII K line, the activity indicator SFEROS, the asymmetry of the cross-correlation function, the line depth ratio of the VI/FeI lines, and the TiO, CaH2, CaH3, CaOH, and Hα indices. We complemented the RV measurements with a 14-day optical/infrared photometric monitoring to look for signatures of activity or varying accretion. Results. We found that the RV of EX Lup is periodic (P =7.417 d), with stable period, semi-amplitude (2.2 km s−1), and phase over at least four years of observations. This period is not present in any of the above-mentioned activity indicators. However, the RV of narrow metallic emission lines suggest the same period, but with an anti-correlating phase. The observed absorption line RVs can be fitted with a Keplerian solution around a 0.6 M⊙ central star with M2 sin i=(14.7±0.7)MJup and eccentricity of e =0.24. Alternatively, we attempted to model the observations with a cold or hot stellar spot as well. We found that in our simple model, the spot parameters needed to reproduce the RV semi-amplitude are in contradiction with the photometric variability, making the spot scenario unlikely. Conclusions. We qualitatively discuss two possibilities to explain the RV data: a geometry with two accretion columns rotating with the star, and a single accretion flow synchronized with the orbital motion of the hypothetical companion; the second scenario is more consistent with the observed properties of EX Lup. In this scenario, the companion’s mass would fall into the brown dwarf desert, which, together with the unusually small separation of 0.06 au would make EX Lup a unique binary system. The companion also has interesting implications on the physical mechanisms responsible for triggering the outburst. Accepted by A&A http://arxiv.org/pdf/1311.4177

Interstellar chemistry of nitrogen hydrides in dark clouds R. Le Gal1, P. Hily-Blant1,2, A. Faure1, G. Pineau des Forêts3,4, C. Rist1 and S. Maret1 1 UniversitéJoseph Fourier/CNRS, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, France 2 Institut Universitaire de France 3 Universitéde Paris Sud/CNRS, IAS (UMR 8617), Orsay, France 4 LERMA / CNRS (UMR 8112) / Observatoire de Paris, France E-mail contact: romane.legal at obs.ujf-grenoble.fr, pierre.hily-blant at obs.ujf-grenoble.fr, alexandre.faure at obs.ujf- grenoble.fr Nitrogen, amongst the most abundant metals in the interstellar medium, has a peculiar chemistry which differs from those of carbon and oxygen. Recent observations of several nitrogen-bearing species in the interstellar medium suggest abundances in sharp disagreement with current chemical models. Although some of these observations show that some gas-grains processes are at work, gas-phase chemistry needs first to be revisited. Strong constraints are provided by recent Herschel observations of nitrogen hydrides in cold gas. The aim of the present work is to perform a comprehensive analysis of the interstellar chemistry of nitrogen, focussing on the gas-phase formation of the smallest polyatomic species and in particular nitrogen hydrides. We present a new chemical network in which the kinetic rates of critical reactions have been updated based on recent experimental and theoretical studies, including nuclear spin branching ratios. Our network thus treats the different spin symmetries of the nitrogen hydrides self-consistently together with the ortho and para forms of molecular hydrogen. This new network is used to model the time evolution of the chemical abundances in dark cloud conditions. The steady-state results are analysed, with special emphasis on the influence of the overall amounts of carbon, oxygen, and sulphur. Our calculations are also compared with Herschel/HIFI observations of NH, NH2, and NH3 detected towards the external envelope of the protostar IRAS 16293-2422. The observed abundances and abundance ratios are reproduced for a C/O gas-phase elemental abundance ratio of ∼ 0.8, provided that the

24 −3 sulphur abundance is depleted by a factor larger than 2. The ortho-to-para ratio of H2 in these models is ∼ 10 . Our models also provide predictions for the ortho-to-para ratios of NH2, and NH3 of ∼ 2.3 and ∼ 0.7 respectively. We conclude that the abundances of nitrogen hydrides in dark cloud conditions are consistent with the gas-phase synthesis predicted with our new chemical network. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1311.5313

Dynamical Friction in a Gas: The Supersonic Case Aaron T. Lee1 and Steven W. Stahler1 1 Astronomy Department, U. of California, Berkeley, CA 94720 USA E-mail contact: a.t.lee at berkeley.edu Any gravitating mass traversing a relatively sparse gas experiences a retarding force created by its disturbance of the surrounding medium. In a previous contribution (Lee & Stahler 2011), we determined this dynamical friction force when the object’s velocity was subsonic. We now extend our analysis to the supersonic regime. As before, we consider small perturbations created in the gas far from the gravitating object, and thereby obtain the net influx of linear momentum over a large, bounding surface. Various terms in the perturbation series formally diverge, necessitating an approximate treatment of the flow streamlines. Nevertheless, we are able to derive exactly the force itself. As in the subsonic case, we find that F = Mdot*V, where Mdot is the rate of mass accretion onto the object and V its instantaneous velocity with respect to distant background gas. Our force law holds even when the object is porous (e.g., a galaxy) or is actually expelling mass in a wind. Quantitatively, the force in the supersonic regime is less than that derived analytically by previous researchers, and is also less than was found in numerical simulations through the mid 1990s. We urge simulators to revisit the problem using modern numerical techniques. Assuming our result to be correct, it is applicable to many fields of astrophysics, ranging from exoplanet studies to galactic dynamics. Accepted by A&A http://arxiv.org/pdf/1311.3445

Sejong Open Cluster Survey (SOS). II. IC 1848 Cluster in the H II Region W5 West Beomdu Lim1, Hwankyung Sung1, Jinyoung S. Kim2, Michael S. Bessell3 and Rivkat Karimov4 1 Department of Astronomy and Space Science, Sejong University, 209 Neungdong-Ro, Gwangkjin-Gu, Seoul, Republic of Korea 2 Steward Observatory, University of Arizona, 933 N. Cherry Ave. Tucson, AZ 85721-0065, USA 3 RSAA, College of Mathematical and Physical Sciences, The Australian National University, Cotter Road, Weston, ACT 2611, Australia 4 Ulugh Beg Astronomical Institute, 33 Astronomical Street, Tashkent 700052, Uzbekistan E-mail contact: sungh at sejong.ac.kr IC 1848 is one of the young open clusters in the giant star forming Cas OB6 association. Several interesting aspects relating to star formation processes in giant star forming regions attracted us to study the initial mass function (IMF), star formation mode, and properties of pre-main sequence stars (PMS). A UBVI and Hα photometric study of the young open cluster IC 1848 was conducted as part of the “Sejong Open cluster Survey” (SOS). We have selected 105 early-type members from photometric diagrams. Their mean reddening is = 0.660 ± 0.054 mag. Using the published photometric data with near- and mid-infrared archival data we confirmed the normal reddening law (RV = 3.1) toward the cluster (IC 1848). A careful zero-age main sequence fitting gives a distance modulus of V0 − MV = 11.7 ± 0.2 mag, equivalent to 2.2 ± 0.2 kpc. H alpha photometry and the list of young stellar objects identified by Koenig et al. permitted us to select a large number of PMS stars comprising 196 Hα emission stars, 35 Hα emission candidates, 5 Class I, 368 Class II, and 24 transition disk candidates. From the Hertzsprung-Russell diagram using stellar evolution models, we estimate an age of 5 Myr from several evolved stars and 3 Myr from the PMS stars. The IMF was derived from stars with mass larger than 3 M⊙, and the slope is slightly steeper (Γ = −1.6 ± 0.2) than the Salpeter/Kroupa IMF. Finally, we estimated the mass accretion rate of PMS stars with a UV excess. The mean −8 −1 mass accretion rate is about 1.4 × 10 M⊙ yr in the mass range of 0.5 M⊙ to 2 M⊙, whereas intermediate-mass

25 −6 −1 stars (≥ 2.5 M⊙) exhibit a much higher accretion rate of M˙ > 10 M⊙ yr . Accepted by MNRAS http://arxiv.org/pdf/1311.6553

Far-infrared extinction mapping of infrared dark clouds Wanggi Lim1 and Jonathan C. Tan1,2 1 Department of Astronomy, University of Florida, Gainesville, FL 32611, USA 2 Department of Physics, University of Florida, Gainesville, FL 32611, USA E-mail contact: wlim7 at ufl.edu Progress in understanding star formation requires detailed observational constraints on the initial conditions, i.e. dense clumps and cores in giant molecular clouds that are on the verge of gravitational instability. Such structures have been studied by their extinction of Near-Infrared (NIR) and, more recently, Mid-Infrared (MIR) background light. It has been somewhat more of a surprise to find that there are regions that appear as dark shadows at Far-Infrared (FIR) wavelengths as long as ∼ 100 µm! Here we develop analysis methods of FIR images from Spitzer-MIPS and Herschel-PACS that allow quantitative measurements of cloud mass surface density, Σ. The method builds upon that developed for MIR extinction mapping (MIREX) (Butler & Tan 2012), in particular involving a search for independent saturated, i.e. very opaque, regions that allow measurement of the foreground intensity. We focus on three massive starless core/clumps in IRDC G028.37+00.07, deriving mass surface density maps from 3.5 to 70 µm. A by-product of this analysis is measurement of the spectral energy distribution of the diffuse foreground emission. The lower opacity at 70 µm allows us to probe to higher Σ values, up to ∼ 1gcm−2 in the densest parts of the core/clumps. Comparison of the Σ maps at different wavelengths constrains the shape of the MIR-FIR dust opacity law in IRDCs. We find it is most consistent with the thick ice mantle models of Ossenkopf & Henning (1994). There is tentative evidence for grain ice mantle growth as one goes from lower to higher Σ regions. Accepted by ApJL http://arxiv.org/pdf/1312.1063

Warm gas towards young stellar objects in Corona Australis - Herschel/PACS observations from the DIGIT key programme Johan E. Lindberg1,2, Jes K. Jørgensen2,1, Joel D. Green3, Gregory J. Herczeg4,5, Odysseas Dionatos1,2,6, Neal J. Evans II3, Agata Karska5 and Susanne F. Wampfler1,2 1 Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 København K, Denmark 2 Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 København Ø, Denmark 3 The University of Texas at Austin, Department of Astronomy, 2515 Speedway, Stop C1400, Austin, TX 78712-1205, USA 4 Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, 100871, PR China 5 Max Planck Institute for Extraterrestrial Physics, Postfach 1312, 85741, Garching, Germany 6 University of Vienna, Department of Astronomy, Türkenschanzstrasse 17, 1180 Vienna, Austria E-mail contact: jlindberg at snm.ku.dk Context: The effects of external irradiation on the chemistry and physics in the protostellar envelope around low-mass young stellar objects are poorly understood. The Corona Australis star-forming region contains the R CrA dark cloud, comprising several low-mass protostellar cores irradiated by an intermediate-mass young star. Aims: We study the effects on the warm gas and dust in a group of low-mass young stellar objects from the irradiation by the young luminous Herbig Be star R CrA. Methods: Herschel/PACS far-infrared datacubes of two low-mass star-forming regions in the R CrA dark cloud are presented. The distribution of CO, OH, H2O,[C ii], [O i], and continuum emission is investigated. We have developed a deconvolution algorithm which we use to deconvolve the maps, separating the point-source emission from the extended emission. We also construct rotational diagrams of the molecular species. Results: By deconvolution of the Herschel data, we find large-scale (several thousand AU) dust continuum and

26 spectral line emission not associated with the point sources. Similar rotational temperatures are found for the warm CO (282 ± 4 K), hot CO (890 ± 84 K), OH (79 ± 4 K), and H2O (197 ± 7 K) emission, respectively, in the point sources and the extended emission. The rotational temperatures are also similar to what is found in other more isolated cores. The extended dust continuum emission is found in two ridges similar in extent and temperature to molecular millimetre emission, indicative of external heating from the Herbig Be star R CrA. Conclusions: Our results show that a nearby luminous star does not increase the molecular excitation temperatures in the warm gas around a young stellar object (YSO). However, the emission from photodissociation products of H2O, such as OH and O, is enhanced in the warm gas associated with these protostars and their surroundings compared to similar objects not suﬀering from external irradiation. Accepted by A&A http://arxiv.org/pdf/1311.7657

Time Monitoring of Radio Jets and Magnetospheres in the Nearby Young Stellar Cluster R Coronae Australis Hauyu Baobab Liu1, Roberto Galván-Madrid2, Jan Forbrich3, Luis F. Rodr´ıguez4, Michihiro Takami1, Gráinne Costigan2, Carlo Felice Manara2, Chi-Hung Yan1,7, Jennifer Karr1, Mei-Yin Chou1, Paul T.-P. Ho1,8, and Qizhou Zhang8 1 Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei, 106 Taiwan 2 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748, Garching, Germany 3 University of Vienna, Department of Astrophysics, Türkenschanzstrae 17, 1180, Vienna, Austria 4 Centro de Radioastronom´ıay Astrof´ısica, UNAM, A.P. 3-72, Xangari, Morelia, 58089, Mexico 5 School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland 6 Armagh Observatory, College Hill, Armagh BT61 9DG 7 Department of Earth Sciences, National Taiwan Normal University,Taipei, 117 Taiwan 8 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 E-mail contact: hyliu at asiaa.sinica.edu.tw We report JVLA 8–10 GHz (λ=3.0–3.7 cm) monitoring observations toward the YSO cluster R Coronae Australis (RCrA), taken in 2012, from March 15 to September 12. These observations were planned to measure the radio flux variabilities in timescales from 0.5 hours to several days, to tens of days, and up to ∼200 days. We found that among the YSOs detectable in individual epochs, in general, the most reddened objects in the Spitzer observations show the highest mean 3.5 cm Stokes I emission, and the lowest fractional variabilities on <200-day timescales. The brightest radio flux emitters in our observations are the two reddest sources IRS7W and IRS7E. In addition, by comparing with observations taken in 1996–1998 and 2005, we found that the radio fluxes of these two sources have increased by a factor ∼1.5. The mean 3.5-cm fluxes of the three Class I/II sources IRSI, IRS2, and IRS6 appear to be correlated with their accretion rates derived by a previous near infrared line survey. The weakly accreting Class I/II YSOs, or those in later evolutionary stages, present radio flux variability on <0.5-hour timescales. Some YSOs were detected only during occasional flaring events. The source R CrA went below our detection limit during a few fading events. Accepted by ApJ http://arxiv.org/pdf/1311.4761

Evidence of a discontinuous disk structure around the Herbig Ae star HD 139 614 A. Matter1,5, L. Labadie2, A. Kreplin1, B. Lopez3, S. Wolf4, G. Weigelt1, S. Ertel5, J.-U. Pott6, and W.C. Danchi7 1 Max Planck Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany 2 I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany 3 Laboratoire Lagrange, CNRS UMR 7293, UNS - Observatoire de la Côte d’Azur BP 4229, F-06304 Nice Cedex 4, France 4 Universität zu Kiel, Institut für Theoretische Physik und Astrophysik, Leibnitzstr. 15, 24098 Kiel, Germany 5 UJF-Grenoble 1 / CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Greno-

27 ble, F-38041, France 6 Max Planck Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany 7 NASA/GSFC, Greenbelt, MD 20771, USA E-mail contact: alexis.matter@ at obs.ujf-grenoble.fr A new class of pre-main sequence objects has been recently identified as pre-transitional disks. They present near- infrared excess coupled to a flux deficit at about 10 µm and a rising mid-infrared and far-infrared spectrum. These features suggest a disk structure with inner and outer dust components, separated by a dust-depleted region (or gap). We here report on the first interferometric observations of the disk around the Herbig Ae star HD 139614. Its infrared spectrum suggests a flared disk, and presents pre-transitional features,namely a substantial near-infrared excess accompanied by a dip around 6 µm and a rising mid-infrared part. In this framework, we performed a study of the spectral energy distribution (SED) and the mid-infrared VLTI/MIDI interferometric data to constrain thespatial structure of the inner dust disk region and assess its possibly multi-component structure. We based our work on a temperature-gradient disk model that includes dust opacity. While we could not reproduce the SED and interferometric visibilities with a one-component disk, a better agreement was obtained with a two-component disk model composed of an optically thin inner disk extending from 0.22 to 2.3 AU, a gap, and an outer temperature-gradient disk starting at 5.6 AU. Therefore, our modeling favors an extended and optically thin inner dust component and in principle rules out the possibility that the near-infrared excess originates only from a spatially confined region. Moreover, the outer disk is characterized by a very steep temperature profile and a temperature higher than 300 K at its inner edge. This suggests the existence of a warm component corresponding to a scenario where the inner edge of the outer disk is directly illuminated by the central star. This is an expected consequence of the presence of a gap, thus indicative of a pre-transitional structure. Accepted by A&A http://arxiv.org/pdf/1311.5131

Resolved Imaging of the HR 8799 Debris Disk with Herschel Brenda C. Matthews1,2, Grant Kennedy3, Bruce Sibthorpe4, Mark Booth5,2,1,Mark Wyatt3, Hannah Broekhoven-Fiene2,1, Bruce Macintosh6,7, Christian Marois1,2 1 National Research Council of Canada Herzberg Astronomy & Astrophsyics, 5071 W. Saanich Road, Victoria, BC, V9E 2E7, Canada 2 Department of Physics & Astronomy, University of Victoria, 3800 Finnerty Rd, Victoria, BC, V8P 5C2, Canada 3 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, United Kingdom, CB3 0HA 4 SRON Netherlands Institute for Space Research, PO Box 800, NL-9700 AV Groningen, the Netherlands 5 Instituto de Astrof´ısica, Ponticia Universidad Católica de Chile, Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile 6 Lawrence Livermore National Labs, 7000 East Ave, Livermore, CA 94550, U.S.A. 7 Department of Physics & Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Palo Alto, CA U.S.A. E-mail contact: brenda.matthews at nrc-cnrc.gc.ca We present Herschel far-infrared and submillimeter maps of the debris disk associated with the HR 8799 planetary system. We resolve the outer disk emission at 70, 100, 160 and 250 µm and detect the disk at 350 and 500 µm. A smooth model explains the observed disk emission well. We observe no obvious clumps or asymmetries associated with the trapping of planetesimals that is a potential consequence of planetary migration in the system. We estimate that the disk eccentricity must be <0.1. As in previous work by Su et al. (2009), we find a disk with three components: a warm inner component and two outer components, a planetesimal belt extending from 100–310 AU, with some flexibility (±10 AU) on the inner edge, and the external halo which extends to ∼2000 AU. We measure the disk inclination to be 26◦±3◦ from face-on at a position angle of 64◦ E of N, establishing that the disk is coplanar with the star and planets. The SED of the disk is well fit by blackbody grains whose semi-major axes lie within the planetesimal belt, suggesting an absence of small grains. The wavelength at which the spectrum steepens from blackbody, 47±30 µm, however, is short compared to other A star debris disks, suggesting that there are atypically small grains likely populating the halo. The PACS longer wavelength data yield a lower disk color temperature than do MIPS data (24 and 70 µm), implying two distinct halo dust grain populations.

28 Accepted by ApJ http://arxiv.org/pdf/1311.2977

Signatures of infall motions in the images of the molecular emission of the G31.41+0.31 hot molecular core. J.M. Mayen-Gijon1, G. Anglada1, M. Osorio1, L.F. Rodr´ıguez2, S. Lizano2, J.F. Gómez1 and C. Carrasco-González2,3 1 Instituto de Astrof´ısica de Andaluc´ıa, CSIC, Glorieta de la Astronom´ıas/n, E-18008 Granada, Spain 2 Centro de Radioastronom´ıay Astrof´ısica, Universidad Nacional Autónoma de México, Apartado Postal 72-3 (Xan- gari), 58089 Morelia, Michoacán, Mexico 3 Max-Planck-Institut für Radioastronomie (MPIfR), Auf dem Hügel 69, 53121 Bonn, Germany E-mail contact: juanma at iaa.es Although gravitational collapse is supposed to play an essential role in the star formation process, infall motions have been always elusive to detect. So far, only a few observational signatures have been commonly used to claim for the presence of infall. Often these features consist in either “blue asymmetries” or absorption at redshifted velocities (e.g., inverse P Cygni profiles). Both signatures are based only on the shape of the line profile and they do not guarantee by themselves the presence of dominant infall motions. More robust “mapping signatures” can be obtained from images that angularly resolve the infalling gas. Here we present Very Large Array observations of the ammonia inversion transitions (2,2), (3,3), (4,4), (5,5) and (6,6) towards the hot molecular core (HMC) near G31.41+0.31 that show the signatures of protostellar infall theoretically predicted by Anglada et al. The intensity of the ammonia emission is compact and sharply increases towards the centre in the blueshifted velocity channel maps, while it shows a more flattened distribution in the redshifted velocity channels. Additionally, the emission becomes more compact with increasing (relative) velocity for both red- and blueshifted channels. We introduce a new infall signature, the “central blue spot”, easily identifiable in the first-order moment maps. We show that rotation produces an additional, independent signature, making the distribution of the emission in the channel maps asymmetric with respect to the central position, but without masking the infall signatures. All these mapping signatures, which are identified here for the first time, are present in the observed ammonia transitions of G31 HMC. Accepted by MNRAS http://arxiv.org/pdf/1311.2206

HH 1050: a bipolar outflow in L 988 cloud T.A. Movsessian1 and T.Yu. Magakian1 1 Byurakan Observatory, Aragatsotn reg., Armenia E-mail contact: tigmov at web.am, tigmag at sci.am An optical collimated outflow HH 1050 (L 988a) is studied. With the usage of the 2.6 m telescope observations and the data from catalogues and surveys, including the Hubble telescope archive, its morphology is discussed and the bipolar nature of the outflow is confirmed by spectral data. The specific feature of the HH 1050 outflow is its propagation in the wide cone with 30-40◦ opening angle, as well as the presence of both moving condensations and shocked cloudlets. The source of the flow should be one of the components of IRAS 21007+4951 (WISE J210222.70+500308.3) double star. Other young stars in the field also are discussed. Accepted by Astrophysics

Dynamical evolution of star forming regions Richard J. Parker1, Nicholas J. Wright2, Simon P. Goodwin3 and Michael R. Meyer1 1 Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093, Zürich, Switzerland 2 Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield,

29 AL10 9AB, UK 3 Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, UK E-mail contact: rparker at phys.ethz.ch We model the dynamical evolution of star forming regions with a wide range of initial properties. We follow the evolution of the regions’ substructure using the Q–parameter, we search for dynamical mass segregation using the ΛMSR technique, and we also quantify the evolution of local density around stars as a function of mass using the ΣLDR method. The amount of dynamical mass segregation measured by ΛMSR is generally only significant for subvirial and virialised, substructured regions – which usually evolve to form bound clusters. The ΣLDR method shows that massive stars attain higher local densities than the median value in all regions, even those that are supervirial and evolve to form (unbound) associations. We also introduce the Q − ΣLDR plot, which describes the evolution of spatial structure as a function of mass- weighted local density in a star forming region. Initially dense (>1000starspc−2), bound regions always have Q > 1, ΣLDR > 2 after 5 Myr, whereas dense unbound regions always have Q < 1, ΣLDR > 2 after 5Myr. Less dense −2 regions (<100starspc ) do not usually exhibit ΣLDR > 2 values, and if relatively high local density around massive stars arises purely from dynamics, then the Q− ΣLDR plot can be used to estimate the initial density of a star forming region. (A direct application of this work that attempts to constrain the initial conditions of massive star formation in Cyg OB2 can be found in Wright et al. (arXiv: 1311.4537) - also in this Newsletter.) Accepted by MNRAS http://arxiv.org/pdf/1311.3639

The Atomic and Molecular Content of Disks Around Very Low-mass Stars and Brown Dwarfs I. Pascucci1, G. Herczeg2, J. Carr3 and S. Bruderer4 1 LPL/University of Arizona, USA 2 Kavli Institute, China 3 Naval Research Laboratory, USA 4 MPE, Germany E-mail contact: pascucci at lpl.arizona.edu There is growing observational evidence that disk evolution is stellar-mass dependent. Here, we show that these dependencies extend to the atomic and molecular content of disk atmospheres. We analyze a unique dataset of high- resolution Spitzer/IRS spectra from 8 very low-mass star and brown dwarf disks. We report the first detections of + Ne , H2, CO2, and tentative detections of H2O toward these faint and low-mass disks. Two of our [NeII] 12.81 micron emission lines likely trace the hot (≥5,000 K) disk surface irradiated by X-ray photons from the central stellar/sub- stellar object. The H2 S(2) and S(1) fluxes are consistent with arising below the fully or partially ionized surface traced by the [NeII] emission, in gas at ∼600K. We confirm the higher C2H2/HCN flux and column density ratio in brown dwarf disks previously noted from low-resolution IRS spectra. Our high-resolution spectra also show that the HCN/H2O fluxes of brown dwarf disks are on average higher than those of T Tauri disks. Our LTE modeling hints that this difference extends to column density ratios if H2O lines trace warm ≥ 600K disk gas. These trends suggest that the inner regions of brown dwarf disks have a lower O/C ratio than those of T Tauri disks which may result from a more efficient formation of non-migrating icy planetesimals. A O/C=1, as inferred from our analysis, would have profound implications on the bulk composition of rocky planets that can form around very low-mass stars and brown dwarfs. Accepted by The Astrophysical Journal http://adsabs.harvard.edu/pdf/2013arXiv1311.1228P

30 SDC13 infrared dark clouds: Longitudinally collapsing filaments? N. Peretto1,2, G.A. Fuller3, Ph. André2, D. Arzoumanian4, V.M. Rivilla5, S. Bardeau6, S. Duarte Puertas7, J.P. Guzman Fernandez7, C. Lenfestey3, G.-X. Li8, F.A. Olguin9,10, B.R. Röck11,12, H. de Villiers13, J. Williams3 1 School of Physics & Astronomy, Cardi University, Queens Buildings, The parade, Cardi CF24 3AA, UK 2 Laboratoire AIM, CEA/DSM-CNRS-UniverstéParis Diderot, IRFU/Service d’Astrophysique, C.E. Saclay, France 3 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK 4 IAS, CNRS (UMR 8617), UniversitéParis-Sud, Batiment 121, 91400 Orsay, France 5 Centro de Astrobiologia (CSIC-INTA), Ctra. de Torrejón-Ajalvir, km. 4, E-28850 Torrejón de Ardoz, Madrid, Spain 6 Institut de Radioastronomie Millimétrique, 300 Rue de la piscine, F-38406 Saint Martin d’Héres, France 7 Universidad de Granada, 18071 Granada, Spain 8 Max-Planck Institut für Radioastronomie, Auf dem Hügel, 69, 53121 Bonn, Germany 9 School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK 10 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 11 Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife, Spain 12 Universidad de la Laguna, Dept. Astrosica, E-38206 La Laguna, Tenerife, Spain 13 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Herts, AL10 9AB, UK E-mail contact: Nicolas.Peretto at astro.cf.ac.uk Formation of stars is now believed to be tightly linked to the dynamical evolution of interstellar filaments in which they form. In this paper we analyze the density structure and kinematics of a small network of infrared dark filaments, SDC13, observed in both dust continuum and molecular line emission with the IRAM 30m telescope. These observations reveal the presence of 18 compact sources amongst which the two most massive, MM1 and MM2, are located at the intersection point of the parsec-long filaments. The dense gas velocity and velocity dispersion observed along these filaments show smooth, strongly correlated, gradients. We discuss the origin of the SDC13 velocity field in the context of filament longitudinal collapse. We show that the collapse timescale of the SDC13 filaments (from 1 Myr to 4 Myr depending on the model parameters) is consistent with the presence of Class I sources in them, and argue that, on top of bringing more material to the centre of the system, collapse could generate additional kinematic support against local fragmentation, helping the formation of starless super-Jeans cores. Accepted by A&A http://arxiv.org/pdf/1311.0203

Kinematics of the ionized-to-neutral interfaces in Monoceros R2 P. Pilleri1,2,3 , A. Fuente2 , M. Gerin4 , J. Cernicharo3 , J. R. Goicoechea3 , V. Ossenkopf5 , C. Joblin6,7, M. González-Garc´ıa8, S. P. Trevi`no-Morales9, A.´ Sánchez-Monge5,9, J. Pety10, O. Berné6,7, C. Kramer8 1 Los Alamos National Laboratory, P.O. Box 1663, Los Alamos (NM) 87545, USA 2 Observatorio Astronómico Nacional, Apdo. 112, E-28803 Alcaláde Henares (Madrid), Spain 3 Centro de Astrobiolog´ıa, (INTA-CSIC), Ctra. M-108, km. 4, E-28850 Torrejón de Ardoz, Spain 4 LERMA, Observatoire de Paris, 61 Av. de lObservatoire, 75014 Paris, France 5 I. Physikalisches Institut der Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany 6 Universitéde Toulouse, UPS, IRAP, 9 avenue du colonel Roche, 31062 Toulouse cedex 4, France 7 CNRS, UMR 5187, 31028 Toulouse, France 8 Instituto de Radio Astronom´ıaMilimétrica (IRAM), Avenida Divina Pastora 7, Local 20, 18012 Granada, Spain 9 Osservatorio Astrofisico di Arcetri, INAF, Largo E. Fermi 5, I-50125 Firenze, Italy 10 Institut de Radioastronomie Millimétrique, 300 Rue de la Piscine, 38406 Saint Martin d’Héres, France E-mail contact: ppilleri at oan.es Context. Monoceros R2 (Mon R2), at a distance of 830 pc, is the only ultra-compact HII region (UCHII) where its associated photon-dominated region (PDR) can be resolved with the Herschel Space Observatory. Aims. Our aim is to investigate observationally the kinematical patterns in the interface regions (i.e., the transition from atomic to molecular gas) associated with Mon R2.

31 Methods. We used the HIFI instrument onboard Herschel to observe the line profiles of the reactive ions CH+, OH+, + and H2O toward different positions in Mon R2. We derive the column density of these molecules and compare them with gas-phase chemistry models. Results. The reactive ion CH+ is detected both in emission (at central and red-shifted velocities) and in absorption (at blue-shifted velocities). The OH+ ion is detected in absorption at both blue- and red-shifted velocities, with similar + column densities; H2O is not detected at any of the positions, down to a rms of 40 mK toward the molecular peak. At this position, we find that the OH+ absorption originates in a mainly atomic medium, and therefore is associated with the most exposed layers of the PDR. These results are consistent with the predictions from photo-chemical models. The line profiles are consistent with the atomic gas being entrained in the ionized gas flow along the walls of the cavity of the HII region. Based on this evidence, we are able to propose a new geometrical model for this region. Conclusions. The kinematical patterns of the OH+ and CH+ absorption indicate the existence of a layer of mainly atomic gas for which we have derived, for the first time, some physical parameters and its dynamics. Accepted by Astronomy and Astrophysics http://arxiv.org/pdf/1311.1101

Star Formation in Orion’s L1630 Cloud: an Infrared and Multi-epoch X-ray Study David Principe1, J.H. Kastner1, Nicolas Grosso2, Kenji Hamaguchi3,4, Michael Richmond1, William K. Teets5, David A. Weintraub5 1 Chester F. Carlson Center for Imaging Science and the Laboratory for Multiwavelength Astronomy (LAMA), Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623, USA 2 Observatoire Astronomique de Strasbourg, Universitéde Strasbourg, CNRS, UMR 7550, 11 rue de l’Université, F-67000 Strasbourg, France 3 CRESST and X-ray Astrophysics Laboratory NASA/GSFC, Greenbelt, MD 20771, USA 4 Department of Physics, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA 5 Department of Physics & Astronomy, Vanderbilt University, Nashville TN 37235, USA E-mail contact: daveprincipe at astro.rit.edu X-ray emission is characteristic of young stellar objects (YSOs) and is known to be highly variable. We investigate, via a multiwavelength IR/X-ray study of the L1630 dark cloud, whether and how X-ray variability in young stellar objects is related to protostellar evolutionary state. We have analyzed 11 Chandra X-ray Observatory observations, obtained over the course of four years and totaling ∼240 ks exposure time, targeting the eruptive Class I YSO V1647 Ori in L1630. We used 2MASS and Spitzer data to identify and classify IR counterparts to L1630 X-ray sources and identified a total of 52 X-ray emitting YSOs with IR counterparts, including 4 Class I sources and 1 Class 0/I source. We have detected cool (<3 MK) plasma, possibly indicative of accretion shocks, in three classical T Tauri stars. A subsample of 27 X-ray-emitting YSOs were covered by 9 of the 11 Chandra observations targeting V1647 Ori and vicinity. For these 27 YSOs, we have constructed X-ray light curves spanning approximately four years. These light curves highlight the variable nature of pre-main sequence X-ray emitting young stars; many of the L1630 YSOs vary by orders of magnitude in count rate between observations. We discuss possible scenarios to explain apparent trends between various X-ray spectral properties, X-ray variance and YSO classification. Accepted by ApJS http://arxiv.org/pdf/1311.5232

Detection of a Magnetized Disk around a Very Young Protostar Ramprasad Rao1, Josep M. Girart2, Shih-Ping Lai3,4, Daniel P. Marrone5 1 Institute of Astronomy and Astrophysics, Academia Sinica, 645 N. Aohoku Pl., Hilo, HI 96720, USA 2 Institut de Ci´encies de l’Espai, (CSIC-IEEC), Campus UAB, Facultat de Ci´encies, C5p 2, 08193 Bellaterra, Catalonia 3 Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan 4 Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan 5 Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA E-mail contact: girart@ at ice.cat

32 We present subarcsecond resolution polarimetric observations of the 878 µm thermal dust continuum emission obtained with the Submillimeter Array (SMA) towards the IRAS 16293−2422 protostellar binary system. We report the detection of linearly polarized dust emission arising from the circumstellar disk associated with the IRAS 16293−2422 B protostar. The fractional polarization of ∼1.4% is only slightly lower than that expected from theoretical calculations in such disks. The magnetic field structure on the plane of the sky derived from the dust polarization suggests a complex magnetic field geometry in the disk, possibly associated with a rotating disk that is wrapping the field lines as expected from the simulations. The polarization around IRAS 16293−2422 A at subarcsecond angular resolution is only marginally detected. Accepted by ApJL http://arxiv.org/pdf/1311.6225

DN Tauri - coronal activity and accretion in a young low-mass CTTS J. Robrade1, M. Guedel2, H.M. Guenther3 and J.H.M.M. Schmitt1 1 Hamburger Sternwarte, University of Hamburg, 21029 Hamburg, Germany 2 Department of Astronomy, University of Vienna, 1180 Vienna, Austria 3 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA E-mail contact: jrobrade at hs.uni-hamburg.de We present a deep XMM-Newton observation of DN Tau, a young M0-type accreting CTTS and investigate its X-ray properties and X-ray generating mechanisms. Specifically we examine the presence of X-ray emission from magnetic activity and accretion shocks and compare our new X-ray data with UV data taken simultaneously and with X- ray/UV observations performed before. We find that the X-ray emission from DN Tau is dominated by coronal plasma generated via magnetic activity, but also clearly detect a contribution of the accretion shocks to the cool plasma component at about 2 MK as consistently inferred from density and temperature analysis. Strong variations in the emission measure of the cooler plasma components between the 2005 and 2010 XMM data point to accretion related changes. Typical phenomena of active coronae like flaring, the presence of very hot plasma at 30 MK and an abundance pattern showing the inverse FIP effect are also seen on DN Tau. The UV light curve taken simultaneously is in general not related to the X-ray brightness, but exhibits clear counterparts during the observed X-ray flares. The X-ray properties of DN Tau are similar to those of more massive CTTS, but its low mass and large radius shift the accretion shocks to lower temperatures, reducing their imprint in the X-ray regime. Accepted by A&A http://arxiv.org/pdf/1311.4461

The Dynamics of Ultracompact HII Regions Nathaniel Roth1, Steven W. Stahler2 and Eric Keto3 1 Physics Dept,, U. of California, Berkeley, CA 94720, USA 2 Astronomy Dept., U. of California, Berkeley CA 94720, USA 3 Harvard-Smithonian Center for Astrophysics, Cambridge, MA 02138, USA E-mail contact: nathaniel.roth at berkeley.edu Many ultracompact HII regions exhibit a cometary morphology in radio continuum emission. In such regions, a young massive star is probably ablating, through its ultraviolet radiation, the molecular cloud clump that spawned it. On one side of the star, the radiation drives an ionization front that stalls in dense molecular gas. On the other side, ionized gas streams outward into the more rarefied environment. This wind is underpressured with respect to the neutral gas. The difference in pressure draws in more cloud material, feeding the wind until the densest molecular gas is dissipated. Recent, time-dependent simulations of massive stars turning on within molecular gas show the system evolving in a direction similar to that just described. Here, we explore a semi-analytic model in which the wind is axisymmetric and has already achieved a steady state. Adoption of this simplified picture allows us to study the dependence of both the wind and its bounding ionization front on the stellar luminosity, the peak molecular density, and the displacement of the star from the center of the clump. For typical parameter values, the wind accelerates transonically to a speed

33 of about 15 km/s, and transports mass outward at a rate of 10−4 msun/yr. Stellar radiation pressure acts to steepen the density gradient of the wind. Accepted by MNRAS http://arxiv.org/pdf/1311.5912

Reconstructing the density and temperature structure of prestellar cores from Herschel data: A case study for B68 and L1689B A. Roy1, Ph. André1, P. Palmeirim1, M. Attard1, V. Könyves1,2, N. Schneider1,3, N. Peretto1,4, A. Men’shchikov1, D. Ward-Thompson5, J. Kirk5, M. Griffin4, K. Marsh4, A. Abergel2, D. Arzoumanian2, M. Benedettini6, T. Hill1,7, F. Motte1, Q. Nguyen Luong8, S. Pezzuto6, A. Rivera-Ingraham9,10, H. Roussel11, K. L. J. Rygl6, L. Spinoglio6, D. Stamatellos5, G. White12,13 1 Laboratoire AIM, CEA/DSM-CNRS-UniversitéParis Diderot, IRFU / Service d’Astrophysique, C.E. Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France 2 Institut d’Astrophysique Spatiale, CNRS/UniversitéParis-Sud 11, 91405 Orsay, France 3 Universitéde Bordeaux, Laboratoire d’Astrophysique de Bordeaux, CNRS/INSU, UMR 5804, BP 89, 33271, Floirac Cedex, France 4 School of Physics & Astronomy, Cardiff University, Cardiff, CF29, 3AA, UK 5 Jeremiah Horrocks Institute, University of Central Lancashire, PR1 2HE, UK 6 INAF-Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, I-00133 Rome, Italy 7 Joint ALMA Observatory, Alonso de Cordova´ 3107, Vitacura, Santiago, Chile 8 Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada 9 Universitéde Toulouse; UPS-OMP; IRAP; Toulouse, France 10 CNRS; IRAP; 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4, France 11 Institut d’Astrophysique de Paris, UMR7095 CNRS, UniversitéPierre & Marie Curie, 98 bis Boulevard Arago, F-75014 Paris, France 12 Department of Physics and Astronomy, The Open University, Walton Hall Milton Keynes, MK7 6AA, United Kingdom 13 RAL Space, STFC Rutherford Appleton Laboratory, Chilton Didcot, Oxfordshire OX11 0QX, United Kingdom E-mail contact: arabindo.royatcea.fr Utilizing multi-wavelength dust emission maps acquired with Herschel, we reconstruct local volume density and dust temperature profiles for the prestellar cores B68 and L1689B using inverse-Abel transform based technique. We present intrinsic radial dust temperature profiles of starless cores directly from dust continuum emission maps disentangling the effect of temperature variations along the line of sight which was previously limited to the radiative transfer calculations. The reconstructed dust temperature profiles show a significant drop in core center, a flat inner part, and a rising outward trend until the background cloud temperature is reached. The central beam-averaged dust temperatures obtained for B68 and L1689B are 9.3±0.5 K and 9.8±0.5 K, respectively, which are lower than the temperatures of 11.3 K K and 11.6 K obtained from direct SED fitting. The best mass estimates derived by integrating the volume density profiles of B68 and L1689B are 1.6 M⊙ and 11 M⊙, respectively. Comparing our results for B68 with the near- −2 × λ infrared extinction studies, we find that the dust opacity law adopted by the HGBS project, κλ =0.1 300 µm cm2 g−1, agrees to within 50% with the dust extinction constraints. Accepted by A&A http://arxiv.org/pdf/1311.5086

Discovery of the Young L Dwarf WISE J1741102.78-464225.5 Adam C. Schneider1, Michael C. Cushing1, J. Davy Kirkpatrick2, Gregory N. Mace2,3, Christopher R. Gelino2,4, Jacqueline K. Faherty5, Sergio Fajardo-Acosta2, and Scott S. Sheppard6 1 Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft St., Toledo, OH 43606, USA 2 Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125, USA

34 3 Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547, USA 4 NASA Exoplanet Science Institute, Mail Code 100-22, California Institute of Technology, 770 South Wilson Ave, Pasadena, CA 91125, USA 5 Department of Astronomy, University of Chile, Camino El Observatorio 1515, Casilla 36-D, Santiago, Chile 6 Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Rd. NW, Washington, DC 20015, USA E-mail contact: Adam.Schneider at Utoledo.edu We report the discovery of the L dwarf WISE J174102.78−464225.5, that was discovered as part of a search for nearby L dwarfs using the Wide-field Infrared Survey Explorer (WISE). The distinct triangular peak of the H-band portion of its near-infrared spectrum and its red near-infrared colors (J − KS = 2.35±0.08 mag) are indicative of a young age. Via comparison to spectral standards and other red L dwarfs, we estimate a near-infrared spectral type to be L7±2 (pec). From a comparison to spectral and low-mass evolutionary models, we determine self-consistent effective −2 temperature, log g, age, and mass values of 1450±100 K, 4.0±0.25 (cm s ), 10–100 Myr, and 4–21 MJup, respectively. With an estimated distance of 10-=30 pc, we explore the possibility that WISE J174102.78−464225.5 belongs to one of the young nearby moving groups via a kinematic analysis and we find potential membership in the β Pictoris or AB Doradus associations. A trigonometric parallax measurement and a precise radial velocity can help to secure its membership in either of these groups. Accepted by AJ http://arxiv.org/pdf/1311.5941

The curious morphology and orientation of Orion proplyd HST-10 R. Y. Shuping1, Marc Kassis2, John Bally3 and Mark R. Morris4 1 Space Science Institute, USA 2 W.M. Keck Observatory, USA 3 Center for Astrophysics & Space Astronomy, CU Boulder, USA 4 Dept. of Physics, Astronomy Division, UCLA, USA E-mail contact: rshuping at spacescience.org HST-10 is one of the largest proplyds in the Orion Nebula and is located approximately 1’ SE of the Trapezium. Unlike other proplyds in Orion, however, the long-axis of HST-10 does not align with θ1 C, but is instead aligned with the rotational axis of the HST-10 disk. This cannot be easily explained using current photo-evaporation models. In this letter, we present high spatial resolution near-infrared images of the Orion proplyd HST-10 using Keck/NIRC2 with the Laser Guide Star Adaptive Optics system, along with multi-epoch analysis of HH objects near HST-10 using Hubble Space Telescope WFPC2 and ACS cameras. Our narrow-band near-IR images resolve the proplyd ionization front (IF) and circumstellar disk down to 23 AU at the distance to Orion in Br γ, He I, H2, and PAH emission. Br γ and He I emission primarily trace the IF (with the disk showing prominently in silhouette), while the H2 and PAH emission trace the surface of the disk itself. PAH emission also traces small dust grains within the proplyd envelope which is asymmetric and does not coincide with the IF. The curious morphology of the PAH emission may be due to UV-heating by both θ1 C Ori and θ2 A Ori. Multi-epoch HST images of the HST-10 ﬁeld show proper motion of 3 knots associated with HH 517, clearly indicating that HST-10 has a jet. We postulate that the orientation of HST-10 is determined by the combined ram-pressure of this jet and the FUV-powered photo-ablation ﬂow from the disk surface. Accepted by ApJ Letters http://arxiv.org/abs/1311.1112

Evolutionary tracks of massive stars during formation Michael D. Smith1 1 CAPS, University of Kent, Canterbury, UK E-mail contact: m.d.smith at kent.ac.uk

35 A model for massive stars is constructed by piecing together evolutionary algorithms for the protostellar structure, the environment, the inflow and the radiation feedback. We investigate specified accretion histories of constant, decelerating and accelerating forms and consider both hot and cold accretion, identified with spherical free-fall and disk accretion, respectively. Diagnostic tools for the interpretation of the phases of massive star formation and testing the evolutionary models are then developed. Evolutionary tracks able to fit Herschel Space Telescope data require the generated stars to be three to four times less massive than in previous interpretations, thus being consistent with clump star formation efficiencies of 10 – 15%. However, for these cold Hershel clumps, the bolometric temperature is not a good diagnostic to differentiate between accretion models. We also find that neither spherical nor disk accretion can explain the high radio luminosities of many protostars. Nevertheless, we discover a solution in which the extreme ultraviolet flux needed to explain the radio emission is produced if the accretion flow is via free-fall on to hot spots covering less than 10% of the surface area. Moreover, the protostar must be compact, and so has formed through cold accretion. We show that these conclusions are independent of the imposed accretion history. This suggests that massive stars form via gas accretion through disks which, in the phase before the star bloats, download their mass via magnetic flux tubes on to the protostar. Accepted by MNRAS http://arxiv.org/pdf/1311.3352

Multi-epoch VLBA H2O maser observations toward the massive YSOs AFGL 2591 VLA 2 and VLA 3 J.M. Torrelles1, M.A. Trinidad2, S. Curiel3, R. Estalella4, N.A. Patel5, J.F.Gómez6, G. Anglada6, C. Carrasco-González7,8, J. Cantó3, A. Raga9, L.F. Rodr´ıguez8 1 Instituto de Ciencias del Espacio (CSIC)-UB/IEEC, Universitat de Barcelona, Mart´ıi Franqu‘es 1, 08028 Barcelona, Spain 2 Departamento de Astronom´ıa, Universidad de Guanajuato, Apdo. Postal 144, 36000 Guanajuato, México 3 Instituto de Astronom´ıa(UNAM), Apartado 70-264, 04510 México D. F., México 4 Departament d’Astronomia i Meteorologia and Institut de Ciéncies del Cosmos (IEEC-UB), Universitat de Barcelona, Mart´ıi Franqués 1, 08028 Barcelona, Spain 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 6 Instituto de Astrof´ısica de Andaluc´ıa(CSIC), Apartado 3004, 18080 Granada, Spain 7 Max-Planck-Institut für Radioastronomie (MPIfR), Auf dem Hügel 69, 53121 Bonn, Germany 8 Centro de Radioastronom´ıay Astrof´sica (UNAM), 58089 Morelia, México 9 Instituto de Ciencias Nucleares (UNAM), Apartado 70-543, 04510 México D. F., México E-mail contact: torrelles at ieec.cat

We present multi-epoch Very Long Baseline Array (VLBA) H2O maser observations toward the massive young stellar objects (YSOs) VLA 2 and VLA 3 in the star-forming region AFGL 2591. Through these observations, we have extended the study of the evolution of the masers towards these objects up to a time span of ∼10 yrs, measuring their radial velocities and proper motions. The H2O masers in VLA 3, the most massive YSO in AFGL 2591 (∼30–40 M⊙), are grouped within projected distances of ∼<40 mas (∼<130 AU) from VLA 3. In contrast to other H2O masers in AFGL 2591, the masers associated with VLA 3 are significantly blueshifted (up to ∼30 km s−1) with respect to the velocity of the ambient molecular cloud. We find that the H2O maser cluster as a whole, has moved westwards of VLA 3 between the 2001 and 2009 observations, with a proper motion of ∼1.2 mas yr−1 (∼20 km s−1). We conclude that these masers are tracing blueshifted outflowing material, shock excited at the inner parts of a cavity seen previously in ammonia molecular lines and infrared images, and proposed to be evacuated by the outflow associated with the massive VLA 3 source. The masers in the region of VLA 2 are located at projected distances of ∼0′′. 7 (∼2300 AU) north from this source, with their kinematics suggesting that they are excited by a YSO other than VLA 2. This driving source has not yet been identified. Accepted by MNRAS http://arxiv.org/pdf/1311.1901

36 Pillars and globules at the edges of H II regions, Confronting Herschel observations and numerical simulations P. Tremblin1,2, V. Minier1, N. Schneider3,4, E. Audit1,5, T. Hill1, P. Didelon1, N. Peretto6, D. Arzoumanian7, F. Motte1, A. Zavagno8, S. Bontemps3,4, L.D. Anderson9, Ph. André1, J.P. Bernard10, T. Csengeri11, J. Di Francesco12, D. Elia13, M. Hennemann1, V. Könyves1,7, A.P. Marston14, Q. Nguyen Luong15, A. Rivera-Ingraham16,17, H. Roussel18, T. Sousbie18, L. Spinoglio19, G.J. White20,21, and J. Williams22 1 Laboratoire AIM Paris-Saclay (CEA/Irfu - Uni. Paris Diderot - CNRS/INSU), Centre d’études de Saclay, 91191 Gif-Sur-Yvette, France 2 Astrophysics Group, University of Exeter, EX4 4QL Exeter, UK 3 Univ. Bordeaux, LAB, UMR 5804, F-33270, Floirac, France 4 CNRS, LAB, UMR 5804, F-33270, Floirac, France 5 Maison de la Simulation, CEA-CNRS-INRIA-UPS-UVSQ, USR 3441, Centre détude de Saclay, 91191 Gif-Sur-Yvette, France 6 School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA, UK 7 IAS, CNRS (UMR 8617), UniversitéParis-Sud, Bâtiment 121, 91400 Orsay, France 8 Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388, Marseille, France 9 Department of Physics, West Virginia University, Morgantown, WV 26506, USA 10 Universitéde Toulouse, UPS, CESR, 9 avenue du Colonel Roche, CNRS, UMR 5187, 31028 Toulouse Cedex 4, France 11 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany 12 National Research Council of Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada 13 INAF IAPS, via Fosso del Cavaliere 100, 00133 Roma, Italy 14 European Space Astronomy Centre, Urb. Villafranca del Castillo, PO Box 50727, E-28080 Madrid, Spain 15 Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada 16 Universitéde Toulouse; UPS-OMP; IRAP; Toulouse, France 17 CNRS; IRAP; 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4, France 18 Institut d’Astrophysique de Paris, UniversitéPierre et Marie Curie (UPMC), CNRS (UMR 7095), 75014 Paris, France 19 APS-INAF, Fosso del Cavaliere 100, I-00133 Roma, Italy 20 The Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0NL, UK 21 Department of Physics and Astronomy, The Open University, Milton Keynes, UK 22 Institute for Astronomy, University of Hawaii, 96822 Honolulu, Hawaii, USA E-mail contact: pascal.tremblin at cea.fr Pillars and globules are present in many high-mass star-forming regions, such as the Eagle nebula (M16) and the Rosette molecular cloud, and understanding their origin will help characterize triggered star formation. The formation mechanisms of these structures are still being debated. Recent numerical simulations have shown how pillars can arise from the collapse of the shell in on itself and how globules can be formed from the interplay of the turbulent molecular cloud and the ionization from massive stars. The goal here is to test this scenario through recent observations of two massive star-forming regions, M16 and Rosette. The column density structure of the interface between molecular clouds and H ii regions was characterized using column density maps obtained from far-infrared imaging of the Herschel HOBYS key programme. Then, the DisPerSe algorithm was used on these maps to detect the compressed layers around the ionized gas and pillars in different evolutionary states. Finally, their velocity structure was investigated using CO data, and all observational signatures were tested against some distinct diagnostics established from simulations. The column density profiles have revealed the importance of compression at the edge of the ionized gas. The velocity properties of the structures, i.e. pillars and globules, are very close to what we predict from the numerical simulations. We have identified a good candidate of a nascent pillar in the Rosette molecular cloud that presents the velocity pattern of the shell collapsing on itself, induced by a high local curvature. Globules have a bulk velocity dispersion that indicates the importance of the initial turbulence in their formation, as proposed from numerical simulations. Altogether, this study re-enforces the picture of pillar formation by shell collapse and globule formation by the ionization of highly turbulent clouds.

37 Accepted by A&A http://arxiv.org/pdf/1311.3664

Spatially extended OH+ emission from the Orion Bar and Ridge. Floris van der Tak1, Zsofia Nagy1, Volker Ossenkopf2, Zoltan Makai2, John Black3, Alex Faure4, Maryvonne Gerin5, Ted Bergin6 1 SRON & U Groningen, Netherlands 2 U Cologne, Germany 3 Onsala Space Observatory, Sweden 4 U Grenoble, France 5 LERMA Paris, France 6 U Michigan, USA E-mail contact: vdtak at sron.nl We report the first detection of a Galactic source of OH+ line emission: the Orion Bar, a bright nearby photon- dominated region. Line emission is detected over ∼1′ (0.12 pc), tracing the Bar itself as well as a feature identified as the Southern tip of the Orion Ridge, which borders the Orion Nebula on its Western side. The line width of ∼4 kms−1 + suggests an origin of the OH emission close to the PDR surface, at a depth of AV ∼0.3–0.5 into the cloud where most hydrogen is in atomic form. Steady-state collisional and radiative excitation models require unrealistically high OH+ column densities to match the observed line intensity, indicating that the formation of OH+ in the Bar is rapid enough to influence its excitation. Our best-fit OH+ column density of ∼1×1014 cm−2 is similar to that in previous + + > + + > absorption line studies, while our limits on the ratios of OH /H2O ( ∼ 40) and OH /H3O ( ∼ 15) are somewhat higher than seen before. The column density of OH+ is consistent with estimates from a thermo-chemical model for parameters applicable to the Orion Bar, given the current uncertainties in the local gas pressure and the spectral shape of the ionizing radiation + + + + field. The unusually high OH /H2O and OH /H3O ratios are probably due to the high UV radiation field and electron density in this object. Under Bar-like conditions, photodissociation and electron recombination are more + + effective destroyers of OH than the reaction with H2, which limits the production of H2O . The appearance of the OH+ lines in emission is the result of the high density of electrons and H atoms in the Orion Bar, since for these species, inelastic collisions with OH+ are faster than reactive ones. In addition, chemical pumping, far-infrared pumping by local dust, and near-UV pumping by Trapezium starlight contribute to the OH+ excitation. Similar conditions may apply to extragalactic nuclei where OH+ lines are seen in emission. Accepted by A&A http://arxiv.org/pdf/1311.1977

[CII] Fine Structure Emission: Collisional Excitation by H2 Revisited Laurent Wiesenfeld1 and Paul Goldsmith2 1 UJF-Grenoble, UMR 5274, Grenoble, France 2 Jet Propulsion Laboratory, California Institute of Technology, Pasadena CA, USA E-mail contact: laurent.wiesenfeld at obs.ujf-grenoble.fr C+ is a critical constituent of many regions of the interstellar medium, as it can be a major reservoir of carbon and, under a wide range of conditions, the dominant gas coolant. Emission from its 158 µm fine structure line is used to trace the structure of photon dominated regions in the Milky Way and is often employed as a measure of the star formation rate in external galaxies. Under most conditions, the emission from the single [CII] line is proportional to the collisional excitation rate coefficient. We here used improved calculations of the deexcitation rate of [CII] by collisions + with H2 to calculate more accurate expressions for interstellar C fine structure emission, its critical density, and its cooling rate. The collision rates in the new quantum calculation are ∼ 25% larger than those previously available, and narrow the difference between rates for excitation by atomic and molecular hydrogen. This results in [CII] excitation being quasi-independent of the molecular fraction and thus dependent only on the total hydrogen particle density. A convenient expression for the cooling rate at temperatures between 20 K and 400 K, assuming an LTE H2 ortho

38 kin kin −100 K/T −91.25 K/T + × −24 −3 −1 to para ratio is Λ = 11.5+4.0 e e n(C ) n(H2) 10 ergs cm s . The present work should allow more accurate and convenient analysis of the [CII] line emission and its cooling. Accepted by The Astrophysical Journal

Multi-Wavelength Photometry of the T Tauri Binary V582 Mon (KH 15D): A New Epoch of Occultations Diana Windemuth1 and William Herbst1 1 Astronomy Department, Wesleyan University, Middletown, CT 06459 E-mail contact: dwindemuth at wesleyan.edu We present multi-wavelength (VRIJHK) observations of KH 15D obtained in 2012/13, as well as a master table of standard photometry spanning the years 1967 to 2013. The system is a close, eccentric ’T Tauri-binary’ embedded in an inclined precessing circumbinary (CB) ring. The most recent data show the continued rise of star B with respect to the trailing edge of the occulting horizon as the system’s maximum brightness steadily increases. The wealth of data in time and wavelength domains allows us to track the long-term CCD color evolution of KH 15D. We find that the V-I behavior is consistent with direct and scattered light from the composite color of two stars with slightly different temperatures. There is no evidence for any reddening or bluing associated with extinction or scattering by ISM-sized dust grains. Furthermore, we probe the system’s faint phase behavior at near-infrared wavelengths in order to investigate extinction properties of the ring and signatures of a possible shepherding planet sometimes invoked to confine the CB ring at ∼ 5 AU. The wavelength independence of eclipse depth at second contact is consistent with the ring material being fully opaque to 2.2 microns. The color-magnitude diagrams demonstrate excess flux in J and H at low light levels, which may be due to the presence of a hot, young Jupiter-mass planet. Accepted by AJ http://arxiv.org/pdf/1311.1472

Constraints on Massive Star Formation: Cygnus OB2 was always an Association Nicholas J. Wright1, Richard J. Parker2, Simon P. Goodwin3 and Jeremy J. Drake4 1 University of Hertfordshire, UK 2 ETH Zurich, Switzerland 3 University of Sheﬃeld, UK 4 Smithsonian Astrophysical Observatory, USA E-mail contact: nick.nwright at gmail.com We examine substructure and mass segregation in the massive OB association Cygnus OB2 to better understand its initial conditions. Using a well understood Chandra X-ray selected sample of young stars we ﬁnd that Cyg OB2 exhibits considerable physical substructure and has no evidence for mass segregation, both indications that the association is not dynamically evolved. Combined with previous kinematical studies we conclude that Cyg OB2 is dynamically very young, and what we observe now is very close to its initial conditions: Cyg OB2 formed as a highly substructured, unbound association with a low volume density (< 100 stars/pc3). This is inconsistent with the idea that all stars form in dense, compact clusters. The massive stars in Cyg OB2 show no evidence for having formed particularly close to one another, nor in regions of higher than average density. Since Cyg OB2 contains stars as massive as 100 M⊙ this result suggests that very massive stars can be born in relatively low-density environments. This would imply that the massive stars in Cyg OB2 did not form by competitive accretion, or by mergers. (The numerical simulations and framework on which these results are built is presented in Parker et al. (arXiv 1311.3639) - also in this Newsletter.) Accepted by MNRAS http://arxiv.org/pdf/1311.4537

39 Gap formation in a self-gravitating disk and the associated migration of the embedded giant planet Hui Zhang1, Huigen Liu1, Ji-Lin Zhou1, Robert A. Wittenmyer2 1 School of Astronomy and Space Science & Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University, Nanjing 210093,China 2 Department of Astrophysics, School of Physics, University of NSW, 2052, Australia E-mail contact: huizhang at nju.edu.cn We present the results of our recent study on the interactions between a giant planet and a self-gravitating gas disk. We investigate how the disk’s self-gravity affects the gap formation process and the migration of the giant planet. Two series of 1-D and 2-D hydrodynamic simulations are performed. We select several surface densities and focus on the gravitationally stable region. To obtain more reliable gravity torques exerted on the planet, a refined treatment of disk’s gravity is adopted in the vicinity of the planet. Our results indicate that the net effect of the disk’s self-gravity on the gap formation process depends on the surface density of the disk. We notice that there are two critical values, ΣI and ΣII . When the surface density of the disk is lower than the first one, Σ0 < ΣI , the effect of self-gravity suppresses the formation of a gap. When Σ0 > ΣI , the self-gravity of the gas tends to benefit the gap formation process and enlarge the width/depth of the gap. According to our 1-D and 2-D simulations, we estimate the first critical surface density ΣI ≈ 0.8 MMSN. This effect increases until the surface density reaches the second critical value ΣII . When Σ0 > ΣII , the gravitational turbulence in the disk becomes dominant and the gap formation process is suppressed again. Our 2-D simulations show that this critical surface density is around 3.5 MMSN. We also study the associated orbital evolution of a giant planet. Under the effect of the disk’s self-gravity, the migration rate of the giant planet increases when the disk is dominated by gravitational turbulence. We show that the migration timescale associates with the effective viscosity and can be up to 104 yr. Accepted by RAA http://arxiv.org/pdf/1311.6130

40 Abstracts of recently accepted major reviews

The Dispersal of Protoplanetary Disks Richard Alexander1, Ilaria Pascucci2, Sean Andrews3, Philip Armitage4, Lucas Cieza5 1 University of Leicester, UK 2 University of Arizona, USA 3 Harvard-Smithsonian Center for Astrophysics, USA 4 University of Colorado, USA 5 Universidad Diego Portales, Chile E-mail contact: richard.alexander at leicester.ac.uk Protoplanetary disks are the sites of planet formation, and the evolution and eventual dispersal of these disks strongly influences the formation of planetary systems. Disk evolution during the planet-forming epoch is driven by accretion and mass-loss due to winds, and in typical environments photoevaporation by high-energy radiation from the central star is likely to dominate final gas disk dispersal. We present a critical review of current theoretical models, and discuss the observations that are used to test these models and inform our understanding of the underlying physics. We also discuss the role disk dispersal plays in shaping planetary systems, considering its influence on both the process(es) of planet formation and the architectures of planetary systems. We conclude by presenting a schematic picture of protoplanetary disk evolution and dispersal, and discussing prospects for future work. Accepted by Protostars and Planets VI http://arxiv.org/pdf/1311.1819

The Long-Term Dynamical Evolution of Planetary Systems Melvyn B. Davies1, Fred C. Adams2, Philip Armitage3, John Chambers4, Eric Ford5, Alessandro Morbidelli6, Sean N. Raymond7, Dimitri Veras8 1 Lund University, Sweden 2 University of Michigan, USA 3 University of Colorado, Boulder, USA 4 Carnegie Institution of Washington, USA 5 The Pennsylvania State University, University of Florida, USA 6 University of Nice, France 7 University of Bordeaux, France 8 University of Cambridge, UK E-mail contact: mbd at astro.lu.se This chapter concerns the long-term dynamical evolution of planetary systems from both theoretical and observational perspectives. We begin by discussing the planet-planet interactions that take place within our own Solar System. We then describe such interactions in more tightly-packed planetary systems. As planet-planet interactions build up, some systems become dynamically unstable, leading to strong encounters and ultimately either ejections or collisions of planets. After discussing the basic physical processes involved, we consider how these interactions apply to extrasolar planetary systems and explore the constraints provided by observed systems. The presence of a residual planetesimal disc can lead to planetary migration and hence cause instabilities induced by resonance crossing; however, such discs can also stabilise planetary systems. The crowded birth environment of a planetary system can have a signiﬁcant impact: close encounters and binary companions can act to destabilise systems, or sculpt their properties. In the case of binaries, the Kozai mechanism can place planets on extremely eccentric orbits which may later circularise to produce hot Jupiters. Accepted by Protostars and Planets VI http://arxiv.org/pdf/1311.6816

41 Giant Planet Formation, Evolution, and Internal Structure Ravit Helled1, Peter Bodenheimer2, Morris Podolak1, Aaron Boley3, Farzana Meru4, Sergei Nayakshin5, Jonathan J. Fortney2, Lucio Mayer6, Yann Alibert7, Alan P. Boss8 1 Tel-Aviv University, Israel 2 University of California, Santa Cruz, USA 3 University of Florida, USA & The University of British Columbia, Canada 4 ETH Zürich, Switzerland 5 University of Leicester, UK 6 University of Zürich, Switzerland 7 University of Bern, Switzerland 8 Carnegie Institution, USA E-mail contact: r.helled at gmail.com The large number of detected giant exoplanets offers the opportunity to improve our understanding of the formation mechanism, evolution, and interior structure of gas giant planets. The two main models for giant planet formation are core accretion and disk instability. There are substantial differences between these formation models, including formation timescale, favorable formation location, ideal disk properties for planetary formation, early evolution, planetary composition, etc. First, we summarize the two models including their substantial differences, advantages, and disadvantages, and suggest how theoretical models should be connected to available (and future) data. We next summarize current knowledge of the internal structures of solar- and extrasolar- giant planets. Finally, we suggest the next steps to be taken in giant planet exploration. Accepted by Protostars and Planets VI http://arxiv.org/pdf/1311.1142

42 Dissertation Abstracts

Accretion Variability in Young Stellar Objects

Grainne Costigan

European Southern Observatory, Dublin Institute of Advanced Studies (DIAS), Armagh Observatory, Queen’s Univeristy Belfast Electronic mail: gcostigan at cp.dias.ie Ph.D dissertation directed by: Aleks Scholz, Jorick Vink, Leonardo Testi, Tom Ray Ph.D degree awarded: October 2013

Accretion is one of the dominant sources of radiation from a low mass young stellar object for the first few million years. This process regulates the flow of material and angular momentum from the surroundings to the central object, and is thought to play an important role in the definition of the long term stellar properties. Variability is a well documented attribute of accretion, and has been observed on time-scales ranging from days to years. However it is not clear where these variations come. The current model for accretion is magnetospheric accretion, where the stellar magnetic field truncates the disc, allowing the matter to flow from the disc onto the surface of the star. This model allows for variations in the accretion rate to come from many different sources, such as the magnetic field, the circumstellar disc or the interaction of the different parts of the system. This thesis sets out to use the intrinsic accretion variability to probe the inner regions of these systems. Two spectroscopic surveys were utilised that concentrated on the Hα emission line, which is known to be closely connected to the accretion process. Together, these surveys covered 24 object including low mass T Tauri, intermediate mass T Tauri stars and Herbig Ae stars, on time-scales of minutes, days, weeks, months to years. These two studies found the accretion variations to be less than 1 M⊙/yr and dominated by time-scales close to the rotation period. A further photometric monitoring campaign was undertaken to confirm the short term variations found in the low mass sample. The results from all three of these works are in agreement with each other, and they suggest that the majority of the variations in typical accreting objects are the result of an asymmetric accretion flow. http://homepages.dias.ie/~gcostigan/GCostigan_thesis.pdf

43 New Jobs

Postdoctoral Positions in Astrochemistry and Star/Planet Formation

The Max-Planck-Institute for Extraterrestrial Physics in Garching (near Munich), Germany, invites applications for postdoctoral positions in astrochemistry and observational/theoretical star and planet formation. The aim of the project is to study the formation and earliest phases of pre-stellar cloud cores, their dynamical evolution toward the formation of accretion disks, with links to later stages of protoplanetary disk evolution, planet formation and our Solar System. This will be done by merging astrochemical, magneto-hydrodynamical and radiative transfer models, and constraining them with high sensitivity and high spatial/spectral resolution observations. Researchers with experience in theory and/or observations of star and planet forming regions are encouraged to apply. We also encourage applications from experts in theoretical and/or experimental molecular spectroscopy. The flexible starting date could be as early as Summer 2014, for 2 years guaranteed with the possibility of extension and career development within the Max Planck Institute for Extraterrestrial Physics. Applicants should have a PhD in astronomy or related field before starting. The posts come with a generous travel allowance. Please send a letter of application, a brief description of research interests, a curriculum vitae including bibliography, and three letters of reference by January 31st, 2014 to: Christa Ingram [email protected] Later applications may also be considered in case the posts are not filled until February 2014. The Max-Planck Society is an equal opportunity employer, yet specifically aims to increase the number of female employees.

IGRINS Postdoctoral Fellow

The University of Texas Astronomy Department and McDonald Observatory seek a Postdoctoral Fellow to be the UT lead for the commissioning and early science operations of the Immersion Grating Infrared Spectrograph. IGRINS is a high-resolution spectrograph for the near-IR. It covers all of the H and K atmospheric windows in a single exposure at R=40,000. IGRINS is a joint project of UT and the Korea Astronomy and Space Science Institute. The instrument will reside initially at the McDonald Harlan J. Smith 2.7m telescope but may also used on larger national facilities. Science goals include studies of young stellar objects, late-type stars, solar system objects, and the ISM to be carried out both as key projects and as individual investigations. Commissioning is planned for early 2014 with early science to begin in mid-2014. The postdoc will be actively involved in the planning, execution, and analysis of science programs with the instrument and should lead a major IGRINS observational project. Desired qualifications include one or more of the following: hands-on experience with instrumentation, extensive observing experience, experience developing data reduction software, familiarity with data analysis for high resolution spectroscopy, a track record of astronomical research in an area relevant to IGRINS. Information on research and facilities is available at http://www.as.utexas.edu/ and http://www.as.utexas.edu/astronomy/people/jaffe/jaffe.html Candidates should hold a Ph.D. upon arrival and will reside in Austin. The position has an initial term of one year with expected duration of at least two years, starting July 1, 2014. Applicants should submit a resum, description of research interests, and letters of recommendation from three scientists familiar with the applicant’s experience and research by January 15, 2014 to [email protected]

44 Post-doctoral position in Theoretical Astrophysics

The Theoretical Astrophysics Group at the University of Leicester invites applications for a Post-doctoral Research Associate position in Theoretical Astrophysics. The successful applicant will be expected to carry out independent and collaborative research related to the group’s existing research programme, which covers a broad range of inter- linked areas of contemporary astrophysics (including star and planet formation, AGN physics, accretion discs, galactic dynamics & dark matter). We are particularly interested in candidates with expertise in protoplanetary discs, planet formation or numerical hydrodynamics, but all applicants with a strong background in theoretical astrophysics are encouraged to apply. Applicants must have a PhD in astrophysics (or a related discipline), or expect to be awarded a PhD before taking up the position. The position is available from 1st October 2014 for two years. The salary scale is £31,331–£36,298, depending on experience. The successful applicant will have access to substantial expenses for relocation, travel and computing equipment, as well as extensive access to high-performance computing facilities. Applications should be submitted electronically, via http://www2.le.ac.uk/offices/jobs. Informal enquiries should be directed to Dr Richard Alexander ([email protected]). All applications received by 31st Jan- uary 2014 will be given full consideration.

The 3D Galaxy

The LAM (laboratoire d’astrophysique de Marseille) invites application for a postdoctoral position to work on the 3D distribution of dust and gas in the Milky Way plane. The position is funded through a european FP7-SPACE project named VIALACTEA involving 9 institutes in 7 countries. The applicant will work in close collaboration with Dr. C. Brunt (UNEXE) and Prof. Y. Fukui (UON) to merge and ingest in a large VO-compatible database the spectroscopic galactic plane molecular cubes (mainly UNEXE, UON- NANTEN and NANTEN2 CO survey, plus HOPS, MALT90, and ThrUMMSS/CHaMP data-cubes). A tool will be built and delivered to extract, for a given position, the available spectroscopic information and a distance estimate. Mosaicing of maps will be also produced to derive velocity map on large fields. The final goal is to combine all available data (lines, extinction maps ...) to produce an automated tool for distance estimates and 3D visualization of the Milky Way. Applicant should have a PhD in astrophysics and experience in the field of insterstellar medium with molecular line data-cubes managing and distance determination methods. The application should consist of two reference letters, a curriculum vitae, a publication list and a description of research accomplishments (2 pages). The deadline for applications is December 22, 2013. The position is expected to start in January 2014 for 3 years. Questions and applications should be directed to Delphine Russeil: [email protected]

Triggered star formation in the Galaxy

The Laboratoire d’Astrophysique de Marseille invites application for a postdoctoral position to work on star formation in the Milky Way. The position is funded through the European FP7-SPACE project named VIALACTEA involving 9 institutes in 7 countries. The successful applicant will work on multi wavelength data (images, spectroscopy) to study star formation observed at the edges of Galactic ionized (HII) regions. Observations will be confronted to dedicated models. The aims of this research program is to better understand the role and importance of ionized regions in Galactic star formation. Applicants should have a PhD in astrophysics and experience in the ﬁeld of insterstellar medium, star formation and with infrared to submillimiter data. Application consists of three reference letters, a curriculum vitae, a publication list and a description of research accomplishments (2 pages). The deadline for applications is December 22, 2013. The position is expected to start in January 2014 for 2 years with a possible extension until the completion of the VIALACTEA project in October 2016. Questions and applications should be directed to Annie Zavagno: [email protected]

45 Meetings

First announcement The 2014 STScI Spring Symposium Habitable Worlds Across Time and Space

Space Telescope Science Institute, Baltimore MD (USA) April 28-May 1, 2014

Within a matter of years, humanity will know for the ﬁrst time the frequency of terrestrial planets in orbit around other stars. This knowledge will pave the way for joining research from astronomy, Earth science, and biology to understand the past, present, and future of the Earth within its larger context as one of many habitable worlds throughout the Galaxy. Such work seeks to understand the formation and fate of the Earth as well as predict where and when diﬀerent bodies will be suitable for both simple and complex forms of life.

In this four-day symposium, scientists from diverse ﬁelds will discuss the formation and long-term evolution of terrestrial bodies throughout the various phases of stellar and Galactic evolution. A particular focus will be in how the speciﬁc conditions and challenges for habitability on Earth extend to other bodies in the Solar System and beyond. This symposium will include discussions about sites for Galactic habitability that have not yet been given much attention, such as around post-main sequence stars. The existence of these overlooked environments may provide motivation for novel astronomical observations with existing and next generation ground and space-based observatories.

Invited speakers will cover the following topics:

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

Important information: Abstract submission deadline: February 28, 2014 On-line registration deadline: March 28, 2014 A second announcement containing the procedures for abstract submission and on-line registration will be issued in early January 2014.

For more information on the Symposium and a list of conﬁrmed speakers, please check the website: http://www.stsci.edu/institute/conference/habitable-worlds Please feel free to contact us with an email message to: [email protected].

46 The Interaction of Stars with the Interstellar Medium of Galaxies

Les Houches Physics School 20–25 of April 2014

http://ism2014.strw.leidenuniv.nl

The objective of this school is to provide a comprehensive view of the diﬀerent physical and chemical processes acting in Hii regions, photodissociation regions (PDRs) and shocks in the interstellar medium, as well as the resulting observational characteristics. The school will be complemented with practical activities involving analysis and interpretation of observational data and theoretical models. The lecturers are:

• John Bally (University of Colorado at Boulder, USA) • Jacques Le Bourlot (Universit´eParis-Diderot and Observatoire de Paris, France) • Romano Corradi (Instituto de Astrof´ısica de Canarias, Spain) • Gary Ferland (University of Kentucky, USA) • David Flower (Durham University, UK) • Pierre Hily-Blant (Universit´eJoseph Fourier, France) • Margaret Meixner (Space Telescope Science Institute, USA)

The school will be held at Les Houches Physics School (http://houches.ujf-grenoble.fr), in the village of Les Houches. Les Houches is a village located in Chamonix valley, in the French Alps. Established in 1951, the Physics School is situated at 1150 m above sea level in natural surroundings, with breathtaking views on the Mont-Blanc mountain range. The school is addressed to postgraduate students and postdocs in Astrophysics. The participation is limited to 50 individuals. The registration for the school is now open and the deadline is 15th December 2013, 12:00 pm CET. There will be no registration fee. All participants will be staying at Les Houches School of Physics. The costs of accommodation (individual bedrooms in ’chalets’) and meals during the school (from Sunday 20th night to Friday 25th morning) is 375 euros. The participants are expected to cover their own travel expenses. There are however very limited funds available to cover partially the expenses of some participants. See the website for more information. Information on how to register, as well as more details about the school, can be found on the website: http:// ism2014.strw.leidenuniv.nl

Organizing Committee: Isabel Aleman (Leiden Observatory) Alessandra Candian (Leiden Observatory) Jacques Le Bourlot (Observatoire de Paris) Xander Tielens (Leiden Observatory)

47 Workshop: The Formation of the Solar System 13-15 May 2014 Max Planck Institute of Radioastronomy

With more than 900 confirmed exoplanets, it is becoming clear that there are many planetary systems with rather different properties to that of the Solar System. This poses the question how our own Solar System formed. The answer to this question is not straight forward, because it is based on hints from the current state on what happened in the past. It turns out that this is an interdisciplinary endeavour, requiring knowledge of supernovae explosions, meteorites, cosmochemistry, structure and evolution of circumstellar discs, star cluster dynamics, and the early dynamical evolution of planetary systems. The goal of this workshop is to provide a platform for information exchange between these different disciplines, putting together the puzzle pieces of the Solar System formation history. The workshop focusses on:

• 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

Contributions from related ﬁelds are welcome. More information can be found at: https://indico.mpifr-bonn.mpg.de/theFormationOfTheSolarSystem The workshop will be limited to 40 participants, early registration is recommended. SOC: Melvyn Davies, Matthieu Gounelle, Michael Meyer, Susanne Pfalzner, Simon Portegies Zwart, Ingo Thies

From Galactic to Extragalactic Star Formation (GESF2014) September 8-12, 2014 Palais du Pharo, Marseille, France

Organized by A. Zavagno (LAM) and M. Rouzé(CNES) Scientific Advisory Committee - Frédérique Motte (CEA/AIM Paris-Saclay) (chair) - Frank Bigiel (Zentrum fr Astronomie Heidelberg) (co-chair) - Alberto Bolatto (University of Maryland) - Samuel Boissier (LAM Marseille) - Sylvain Bontemps (Universitéde Bordeaux) - Franoise Combes (Observatoire de Paris) - Clare Dobbs (University of Exeter) - Neal J. Evans II (University of Texas) - Ralf Klessen (Zentrum fr Astronomie Heidelberg) - Sergio Molinari (IAPS-INAF Rome) - Nicola Schneider (Universitéde Bordeaux)

48 Scientific Rationale The conference will focus on observational and computational star formation in the Milky Way and external galaxies, emphasizing the link between these fields. The first aim of this meeting is to bring together the Galactic and extragalactic communities to exchange new results and discuss the perspectives offered by rich existing and forthcoming facilities such as Herschel, Spitzer, Sofia, JWST, as well as radio-telescopes and interferometers such as ALMA, EVLA and the future NOEMA and SKA. The second aim of the conference is to confront the latest results regarding analytical models and simulations to detailed observations of clouds and star formation in the Milky Way and other galaxies. Comprehensive Herschel and Spitzer surveys combined with high-resolution interferometric observations at millimeter wavelengths provide a new, remarkably unified, view of star formation over all cosmic ages. Galactic evolution and star formation rates are now believed to be driven by normal star formation in galactic disks. In the meantime, the origin of the so-called Schmidt-Kennicutt relation is about to be fully understood by means of recent studies in the Milky Way. Besides, cooling lines in the far-infrared with Herschel and Sofia and molecular lines in the (sub)millimeter in particular with ALMA offer exciting opportunities to model cloud kinematics and study ISM chemistry. One can now investigate important parameters of individual star-forming regions such as the efficiency of star formation, the IMF, and the detailed properties of clouds like density structure, turbulence forcing, and Galactic shear. The new challenge we are facing is to fully connect the physical insights gained from detailed studies of Galactic star-forming regions to larger-scale observations and scaling relations found in other galaxies with the final goal of bridging the gap between the Milky Way and galaxies out to highest redshifts.

Preliminary program MW observations - Surveys of the Milky Way: MW structure, cloud scaling relations, variations of the core formation efficiency and star formation rate - Detailed studies of clouds and their formation: cloud density structure, turbulence level, kinematics, impact of OB star clusters, formation mechanisms - Detailed studies of stellar clusters and star formation: star formation efficiency, IMF, clustering and mass segregation, triggered star formation - Extreme environments: the Galactic Center and the tip of the Galactic Bar Extragalactic observations - Studies of star formation and the ISM on super-cloud scales: cloud and star formation in the arms, interarms, and bulge, local versus global regulation of star formation - Extreme environments: low-metallicity galaxies, starbursts regions/galaxies, AGNs, first stars - Scaling relations from nearby to high-z galaxies Modeling - Cloud formation in spiral galaxies and mergers - Cloud properties (structure, turbulence level and forcing) and implication for the star formation rate and IMF - Regulation of star formation: local versus global regulation, clouds under the influence of external pressure, ionization, and shear - Chemistry evolution by dynamical processes such as cloud and star formation http://gesf2014.lam.fr

49 Summary of Upcoming Meetings

Exoplanet Observations with the E-ELT 3 - 6 February 2014 Garching, Germany http://www.eso.org/sci/meetings/2014/exoelt2014.html Herbig Ae/Be stars: The missing link in star formation 7 - 11 April 2014 Santiago, Chile http://www.eso.org/haebe2014.html The Interaction of Stars with the Interstellar Medium of Galaxies 20 - 25 April 2014 Les Houches, France http://ism2014.strw.leidenuniv.nl Habitable Worlds Across Time and Space 28 April - 1 May 2014 Baltimore, USA http://www.stsci.edu/institute/conference/habitable-worlds The Formation of the Solar System 13 - 15 May 2014 MPIfR, Bonn, Germany https://indico.mpifr-bonn.mpg.de/theFormationOfTheSolarSystem The Olympian Symposium on Star Formation 26 - 30 May 2014 Paralia Katerini’s, Mount Olympus, Greece http://zuserver2.star.ucl.ac.uk/~ossf14/ EPoS2014 The Early Phase of Star Formation 1 - 6 June 2014 Ringberg Castle, Tegernsee, Germany http://www.mpia-hd.mpg.de/homes/stein/EPoS/epos.php The Dance of Stars: Dense Stellar Systems from Infant to Old 2 - 6 June 2014 Bad Honnef, Germany http://www.astro.uni-bonn.de/$\sim$sambaran/DS2014/index.html The 18th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun 9 - 13 June 2014 Flagstaﬀ, Arizona, USA http://www2.lowell.edu/workshops/coolstars18/ Summer School on Protoplanetary Disks: Theory and Modeling meet Observations 16 - 20 June 2014 Groningen, The Netherlands http://www.diana-project.com/summer-school Characterizing Planetary Systems Across the HR Diagram 28 July - 1 August 2014 Inst. for Astronomy, Cambridge, USA http://www.ast.cam.ac.uk/meetings/2013/AcrossHR Planet Formation and Evolution 2014 8 - 10 September 2014 Kiel, Germany http://www.astrophysik.uni-kiel.de/kiel2014 Living Together: Planets, Stellar Binaries and Stars with Planets 8 - 12 September 2014 Litomysl Castle, Litomysl, Czech Republic http://astro.physics.muni.cz/kopal2014/ From Galactic to Extragalactic Star Formation 8 - 12 September 2014 Marseille, France http://gesf2014.lam.fr

50 Towards Other Earths II. The Star-Planet Connection 15 - 19 September 2014 Portugal http://www.astro.up.pt/toe2014

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

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51 Obituary

Paola D’Alessio

Paola D’Alessio, our long-time collaborator and close friend, passed away after a long battle with cancer on 14 November 2013. Paola was the world’s leading expert on constructing physically self-consistent accretion disk models for T Tauri stars. These were the first (and perhaps still the only) such models which incorporate the assumption of steady accretion and viscous dissipation as well as iteration to solve the detailed vertical hydrostatic disk structure with irradiation from the central star and accretion shock. Among Paola’s most important papers are those which addressed the issue of dust growth and mixing in T Tauri disks. In D’Alessio et al.1999 (ApJ, 527, 893) she showed that disk models with well-mixed dust with properties like that of the diffuse interstellar medium produced disks that were too vertically thick and produced too much infrared excess, while lacking sufficient mm-wave fluxes. In the second paper of the series (D’Alessio et al.2001, ApJ, 553, 321) Paola and collaborators showed that models with power-law size distributions of dust with maximum sizes around 1 mm produced much better agreement with the mm and infrared emission of most T Tauri disks, but failed to exhibit the 10 micron silicate emission feature usually seen, leading to the conclusion that the large grains must have settled closer to the midplane while leaving a population of small dust suspended in the upper disk atmosphere. This paper provided the first clear empirical evidence for the expected evolution of dust as a step in growing larger bodies in protoplanetary disks. Another important result was the demonstration that once grain growth proceeds past sizes comparable to the wavelengths of observation, the spectral index of the disk emission is determined only by the size distribution of the dust, not its maximum. Along with quantitative calculations of dust properties, the results imply that the typical opacities used to estimate dust masses will generally lead to underestimates of the total solid mass present, a point that is frequently forgotten or ignored. In the third paper of this series (D’Alessio et al.2006, ApJ 638, 314) Paola and her collaborators developed models which incorporated a thin central layer of large dust along with depleted upper disk layers containing small dust. The code which developed these models has been used in over 30 papers to compare with observations, especially those from the Infrared Spectrograph (IRS) (Furlan et al.2005, ApJ, 628, L65; 2006, ApJS, 165, 568; McClure et al. 2010, ApJS 188, 759) as well as the IRAC camera (Allen et al.2004, ApJS, 154, 363) on board the Spitzer Space Telescope, and more recently from PACS on board the Herschel Space Telescope (McClure et al. 2012, ApJ, 759, L10), and from the SMA (Qi. et al. 2011, ApJ 740, 84; 2013, Science 341, 630). Paola’s models also played a crucial role in the recognition of transitional and pre-transitional T Tauri disks, which have substantial, optically-thick outer disks but have inner optically-thin holes or gaps (e.g., Calvet et al.2002, ApJ, 568, 1008; D’Alessio et al.2005, ApJ, 621, 461; Espaillat et al.2007, ApJ, 670, L135; 2010, ApJ 717, 441). In many

52 cases, particularly those of the pre-transitional disks, finding evidence for an inner hole or gap from the spectral energy distribution depends upon careful and detailed modeling. The inference of gaps and holes from the SEDs is now being increasingly confirmed directly by mm- and sub-mm imaging (e.g., Hughes et al.2009), showing reasonable agreement in most cases with the hole sizes predicted by the models. Combining imaging with SED modeling in the future will place additional constraints on the properties of dust in protoplanetary disks. Paola’s influence in the community extended well beyond her direct contributions to the literature in over 100 refereed papers. She provided disk models for many other researchers as well as detailed dust opacities. The insight provided by her calculations informed many other investigations, as studies of X-ray heating of protoplanetary disk atmospheres (Glassgold et al. 2004, ApJ, 615, 808; 2007, ApJ 656, 515; 2009, ApJ 701, 142), of the chemical structure of protoplanetary disks and propagation of high energy radiation (Fogel et al. 2011, ApJ 726; Bethell and Bergin 2011, ApJ 740, 7, 29) and of the photoevaporation of protoplanetary disks (Ercolano et al 2008, ApJ 688, 398). Paola’s passing is a great loss to the star formation community, but we remain grateful for her contributions to our field.

Nuria Calvet Lee Hartmann