THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 248 — 11 August 2013 Editor: Bo Reipurth ([email protected]) List of Contents

The Star Formation Newsletter Interview ...... 3 My Favorite Object ...... 6 Editor: Bo Reipurth [email protected] Abstracts of Newly Accepted Papers ...... 10

Technical Editor: Eli Bressert Dissertation Abstracts ...... 44 [email protected] Meetings ...... 45 Technical Assistant: Hsi-Wei Yen Meetings of Possible Interest ...... 47 [email protected]

Editorial Board

Joao Alves Alan Boss Cover Picture Jerome Bouvier Lee Hartmann The image, obtained with the Hubble Space Tele- Thomas Henning scope, shows photoevaporating globules embedded Paul Ho in the Carina Nebula. Jes Jorgensen Charles J. Lada Image courtesy NASA, ESA, N. Smith (University Thijs Kouwenhoven of California, Berkeley), and The Hubble Heritage Michael R. Meyer Team (STScI/AURA) Ralph Pudritz Luis Felipe Rodr´ıguez Ewine van Dishoeck Hans Zinnecker

The Star Formation Newsletter is a vehicle for Submitting your abstracts fast distribution of information of interest for as- tronomers working on star and planet formation Latex macros for submitting abstracts and molecular clouds. You can submit material and dissertation abstracts (by e-mail to for the following sections: Abstracts of recently [email protected]) are appended to each accepted papers (only for papers sent to refereed Call for Abstracts. You can also submit via the journals), Abstracts of recently accepted major re- Newsletter web interface at http://www2.ifa. views (not standard conference contributions), Dis- hawaii.edu/star-formation/index.cfm sertation Abstracts (presenting abstracts of new Ph.D dissertations), Meetings (announcing meet- ings broadly of interest to the star and planet for- mation 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- quest information from the community). Addition- ally, the Newsletter brings short overview articles on objects of special interest, physical processes or theoretical results, the early solar system, as well as occasional interviews. Newsletter Archive www.ifa.hawaii.edu/users/reipurth/newsletter.htm

2 ficult, was to give up my tenure track position and go to the University of California at Berkeley on a second post- David Hollenbach doc, essentially, to pursue research. I loved the people in in conversation with Bo Reipurth the astronomy department there, and they were incredi- bly supportive to me, especially Chris McKee, with whom I have had a lifelong collaboration and friendship. Even- tually, in 1980, I got my permanent position at NASA Ames, but maintained ties to UC Berkeley. My teaching experience actually gave me a much better foundation on which to do research, and I found that I loved research and working one on one with graduate students and postdocs, rather than teaching large classes. I might say, also, that a 1977 workshop in Erice, Italy on infrared astronomy had a profound influence on my career. I left really feeling that infrared astronomy was going to be very exciting in the coming decades, and decided to focus my research on areas relevant to infrared astronomy. That ultimately led to my being hired at NASA Ames, since IR astronomy was one of its key areas with the Kuiper Air- borne Observatory, and its involvement in IRAS, SIRTF Q: You had a slow start to your research career? Was that (Spitzer), and LDR (this idea eventually ended up as Her- circumstances or choice? schel). I also met a graduate student, Xander Tielens, in A: It was a combination of the two. The circumstances Erice, and he became my first postdoc at NASA Ames af- were these. I was from a small, conservative town in west- ter he graduated from Leiden. It was, as you say, a slow ern Michigan, and left that area to do my PhD at Cornell start, filled with much anxiety, but very interesting and in 1964. I then left Cornell to do a postdoc at Harvard rewarding. Luck and relationships had a lot to do with it. in 1968. For those too young to experience those years, Q: Your two first papers, from 1971, dealt with the role of let me say they were intense and, for me, life changing grains in the formation of molecular hydrogen, and they and mind changing. There was ”the War”, civil rights and have had a major influence on the subject. How have your black power, women’s liberation, and major changes in the results held up 40+ years hence? way you thought about relationships, religion, politics, the environment, music, drugs, dress and work. By the time A: Of course, I am prejudiced, but I think they have held I got to Harvard, I was very alienated from the status up quite well. One of the key issues then and now is that, quo. It seemed that academia was a competitive game on a pure surface with weak van der Waal forces dominat- compared to the issues of the military industrial complex, ing and no enhanced binding sites, the hydrogen atoms the devastation of the environment, the oppression of mi- would evaporate (sublimate) before finding each other to norities and women, the complicity of the media, and the form a molecule if the grain temperature was more than isolation of the individual consumer in ”established” soci- about 10-20 K. Such results were found in the laboratory ety. So I wasted two years at Harvard, and worked mainly in the 80’s and 90’s by Vidali, Pirronello and their cowork- with a group of folks starting one of the first organic food ers. However, there could be sites where at least partial stores and restaurants in Cambridge. My wife and I then chemical bonds held the atomic hydrogen, so that it would left to join the commune which provided much of the or- not evaporate from the surface. In our 1971 paper, we al- ganic food on a farm in Vermont. lowed for this by having what we called ”impurity sites”, although the number of them was a free parameter. The choices were these. I had an epiphany in Vermont. My wife and I were starved for intellectual stimulation. On the theoretical front, there has been much elaboration The thought came to me that one should make the most lately of this idea, by Cazaux and Tielens, and by Cuppen of one’s abilities in the world. So I chose to return to et al. These studies indicate that even at grain tempera- academia, and was lucky (jobs were very scarce then, as tures as high as 100 K, the formation rates of molecular they are now) to get physics and astronomy teaching jobs hydrogen may only be down roughly an order of magni- in Colorado from 1971 to 1975. I had gone to graduate tude from their low temperature rates. school thinking I would be a college teacher, like my fa- On the observational front, it is clear that in PDRs with ther, so I returned to that vision. However, I discovered nearby massive stars the grains are heated to at least 50 K that I had too much ”stage fright” to be in front of class and still the molecular hydrogen is forming quite efficiently after class. So my second choice, which was even more dif-

3 on their surfaces (Habart et al had a nice paper on this faces, and potential chemical reactions of these elements in 2004). Interstellar grain surfaces are likely so complex on the grain surfaces. My own group has been working that, at this point, I favor this approach of observing PDRs hard on this problem, and so have a number of PDR mod- and inferring the rates of molecular hydrogen formation as elers in Europe and the US. Observationally, one of the a function of grain temperature by matching observations key stimulants to this work has been the observed low with PDR models. abundance of gas phase water and molecular oxygen (seen by SWAS, Odin and Herschel, for example), as well as re- Q: Your most cited work is the series of papers on molecule + + cent observations of molecular ions like OH , H2O , and formation and infrared emission in fast interstellar shocks + together with Chris McKee. When you worked on this, did H3O . you realize that this would have such a profound impact in Another thing that comes to mind is the possible role of the community? turbulence in PDRs, stressed especially by Falgarone and A: I got interested in shock waves through my friend Dick her collaborators, in heating the gas and modifying the McCray, who had worked on the expansion of wind-driven chemistry. PDR models sometimes seem to lack sufficient bubbles in the ISM. He called the ISM ”violent”, and that heating to explain the observations of, for example, mid J impressed me. When I got to Berkeley, there had been CO transitions or pure rotational H2 transitions. In a way, some observations of vibrational emission of molecular hy- this is like a model which combines shocks and PDRs. drogen in Orion by Treffers, Gautier and Larson, and Steve Q: Your latest paper is on interstellar H2O masers. How Beckwith and coworkers also observed it around this time. have your thoughts on such masers evolved since you first Mike Shull was visiting Berkeley and he and I worked on began work on this 20 years ago? shock models of this emission. That was the start. Then, I A: There have been considerably more observations in the started working with Chris and we went much more deeply past 20 years that give evidence that water masers are into shocks, expanding the velocity range of the shocks often connected with shocks, especially shocks driven by and the postshock chemistry and infrared emission. From jets and outflows around young stars into the very dense Dick’s comments on the violent interstellar medium, I did medium that surrounds these objects. So even though I think that theoretical models of shocks would have a big was convinced by our maser shock models of 1989-1992, I impact. We could see observationally that the ISM was am even more convinced now. shaped by expanding HII regions, winds, and supernovae- driven shocks. I will confess one thing, however. With One thing I have struggled with, and we address in our re- the exception of my work on masers, shocks were a little cent paper, is the question of whether C shocks or J shocks disappointing to me. The reason is that I love it when are the dominant maser excitation mechanism. Kaufman theory matches well with observation, that is so satisfy- and Neufeld theoretically examined C shock masers, and ing! However, the problem with shocks then was that the Melnick and collaborators observed water masers from dif- telescopes had too poor angular resolution, so that the ferent levels, and they showed that there are water masers shock regions were a mix of shocks of various speeds and that are likely to be excited in C shocks, which can pro- preshock densities, so that to match, say, 4 infrared lines, duce a hotter masing region than the J shock that we mod- you needed 4 shocks of various speeds! I am exaggerating, eled. In these sources, the higher lying maser lines were but I do remember frustration. relatively strong compared to the lower lying 22 GHz line which is typically observed. However, our analysis sug- Q: Your Annual Reviews article with Xander Tielens on gests that J shocks are likely a very significant source of Dense Photodissoctaion Regions summarized our under- water maser emission in general, especially in the large standing of these regions at the time. Since then, have we number of water masers where the 22 GHz line is observed, gained any observational or theoretical understanding that but the higher lines are not. has changed the way we see PDRs? The interesting thing that connects this question with A: I think the big change since those reviews has been in a previous one, is that the J shock masers rely on the understanding that grain surface chemistry has a big im- reformation of molecular hydrogen (the J shocks destroy pact on the chemical structure of PDRs and of molecular pre-existing H2 and other molecules) on relatively warm clouds. As a footnote, I would say it is getting increas- grain surfaces. The shocks that produce masers have high ingly difficult to say where a PDR ends, and an opaque preshock hydrogen densities of greater than 106 cm−3 and, molecular core begins. Even at depths of AV ∼ 10 into a as a result, heat the postshock grains to temperatures of cloud, the effects of FUV radiation can be important not 50-100 K. So we must rely on molecular hydrogen forma- only dissociating molecules, but in photodesorbing them tion at these fairly high grain temperatures. Once the H2 off the grain surfaces. By grain surface chemistry I do not reforms, rapid chemical reactions convert all the oxygen mean the formation of molecular hydrogen here, but the not in CO into H2O and the warm H2O is collisionally freezing out of species like oxygen and carbon on grain sur-

4 excited to produce the maser transitions. subject had Frank as a co-author. This work remains to Q: You did early work on the dispersal of disks around this day as my favorite research topic. young stars, summarized in your Protostars and Planets Q: You moved into the Sierra Mountains when you retired. IV review. Is this subject at the moment driven by obser- How has that change in your life been? vations or by theory? A: That is a very long story, but I will be brief. In a A: My sense is that the theoretical models have become way, this move was a return to “unfinished business” from very detailed, with considerable chemistry, heating and the days of Vermont. My wife and I just had not gotten cooling, radiative transfer, hydrodynamics, and consider- enough of the country life, and had grown tired of the ation of the effects of both viscous evolution and photo- urban life. We love nature, backpacking, hiking, cross evaporation. The observations of gas lines are difficult country skiing, growing our own vegetables and fruit, even as the lines are weak and the grain continuum strong. raising cows now (although they are ”pets” and mobile Many of the observations have been of grain continuum lawnmowers on our 50 acres, and not for slaughter). Like spectra (SEDs). In addition, to make better progress we Vermont, we have a sort of communal situation. However, need spectrally resolved data, or resolving powers of a few there is no lack of intellectual stimulation here, as there km/s in the IR and sub-km/s at the submillimeter and mil- was in Vermont. For example, there are 4 other couples limeter wavelengths that probe the outer disk. Resolving up here who have retired or semi-retired from astronomy the disks spatially would also help, but that requires sub- research, and there are a number of artists, journalists, arcsecond resolution. So I think observations (especially K-12 teachers, etc. Some are starting wineries, which we of the gas) lag theory a bit, even though we theorists have highly encourage! Oddly enough, there is more social life been greatly stimulated by those available. ALMA should than my wife and I experienced in Berkeley, where we really help the situation. I look forward to seeing ALMA lived for 30 years. In the city, our friends were always data as it comes in, and to heterodyne receivers on SOFIA so busy and hassled! And traffic and parking! Both my that can observe the [OI] 63 um line. wife and I continue to work, thanks to the marvel of high Q: Who would you say have had the most important in- speed internet, and visits to talk with colleagues in the fluence on your scientific career? Bay area. One difference for me is that I get to work on just the things I am most interested in. A: The first important influence was Ed Salpeter, my PhD advisor at Cornell. He was an inspiration to me as a per- Q: What are the scientific issues that currently most in- son and as a great scientist. Then, Dick McCray, who terest you? became my friend in Cambridge (actually housed me and A: My big interest right now is trying to understand the my wife as we retreated from Vermont), and then later evolution of protoplanetary disks. I have the good for- inspired me to get back into research. My first research tune to have a great collaborator, Uma Gorti, and she and paper after Harvard was with Dick, a collaboration where I are making models of the evolution of disks, including I commuted to Boulder to work with him during my last photoevaporation, winds, viscous evolution, planet forma- two years teaching in Colorado Springs. Chris McKee gave tion and its effect on disks, grain evolution, etc. We are me a second chance, perhaps risky on his part given my hoping to get funding to construct comprehensive models sketchy history, by awarding me a 3-year postdoc in 1977. that follow evolution for millions of years, and perhaps Since then, he has been a constant influence and inspira- even understand why Kepler has seen so many Neptunes, tion. When I got to NASA Ames in 1979, Ed Erickson compared with Jupiters. became a strong influence and introduced me to the in- The second big interest is in mapping [CII] 158um emis- tricacies of IR spectroscopic observations and instrumen- sion in the Galaxy with km/s resolution and combining tation. Xander Tielens came to Ames in about 1982 as these observations with those of atomic H 21 cm, [CI] fine my first postdoc, and remained a long-time collaborator, structure, and CO rotational emission to try to understand friend, and influence. Finally, Frank Shu, who was such a how giant molecular clouds form and dissipate. This is a strong influence on the Center for Star Formation Studies, big effort with a large group including Chris Walker, Paul which I ran from 1985 to about 2005. This Center was a Goldsmith, Juergen Stutzki, and a host of others and we collaboration of theorists at NASA Ames, UC Berkeley, are hopeful of getting a second flight of our STO (Strato- and UC Santa Cruz, and had a strong influence, I think, spheric Terahertz Observatory) balloon mission for this on all who attended our monthly meetings and summer purpose. workshops. The discussions were lively, and Frank was of- ten at the center of them. An example I can give of the stimulating effect of such a group interaction was that my own interest in disk dispersal and photoevaporation grew from discussions at the Center, and my first papers on the

5 mag in the K band (Borgman et al. 1970). During the next decades a picture emerged that this was indeed a My Favorite Object young cluster with a large population of O/B supergiants Westerlund 1 and possibly M supergiants (Westerlund 1987). The youth led to the suggestion that the high reddening was directly by Morten Andersen associated with the cluster. The early studies were severely limited by spatial resolu- tion and the low sensitivity at near-infrared wavelengths. The next breakthrough was the advent of the near-infrared imaging arrays. It then became directly clear that West- erlund 1 indeed is a massive cluster. Fig. 1 shows a JHK color composite of the central 4′ ×4′ of Westerlund 1. The large contrast between the bright supergiants in the cluster and the fainter, much more numerous, low-mass stars is an observational challenge. Whereas the supergiants have magnitudes as bright as H=6, an 0.1 M⊙ 4 Myr pre-main sequence star will have an apparent magnitude of H=19 due to extinction and distance.

Most stars form in clusters and in clustered environments. Any complete theory of star formation thus have to be able to reproduce the observations of young clusters and clustered star formation. Although many low mass star forming regions have been observed in details, our knowl- 4 edge of very massive ones (more massive than 10 M⊙) is limited. The massive clusters provide us with a unique link to extragalactic astronomy since only massive star clusters can be detected as individual objects at cosmological dis- tances. However, they are either marginally resolved or unresolved outside the Local Group and their properties have to be obtained through their integrated properties. The embedded cluster mass function is, at least as found within 2 kpc, well represented by a power law with a slope of −2 in linear units (Lada & Lada 2003). Therefore, for statistical reasons, massive clusters are relatively rare and they are therefore also expected to be far away on average. This has proved to be the case in that clusters 4 more massive than some 10 M⊙ are located at 6 kpc or more (NGC 3603, the Arches and R 136 in the Large Magellanic Cloud). Fortunately, however, Westerlund 1 was realized to be the most massive young star cluster Figure 1: JHK image of Westerlund 1 as seen with the known in the Galaxy and only at a distance of 3-5 kpc. NTT/SOfI (from Brandner et al. 2005). The field-of-view The closer distance combined with a larger core radius is 4′ × 4′, corresponding to 4.8pc×4.8pc for a distance of than e.g. NGC 3603 makes it a much easier target to 4kpc. The faintest stars visible are around 3 M⊙. observe.

The importance of Westerlund 1 To determine the massive evolved stellar content of West- erlund 1, Clark et al. (2005) obtained additional spectra of Westerlund 1 is a unique object in the Galaxy. It has been some 50 objects in the cluster, found them all to be post- known since the early 60s when Bengt Westerlund noticed main sequence objects and suggested that the initial clus- a heavily reddened cluster (Westerlund 1961). Early in- ter mass, extrapolating the IMF to the full stellar regime, 5 frared photometry revealed a dozen stars brighter than 5 could be as high as 10 M⊙. This would be a comparable

6 mass to R136 in the 30 Dor region in the Large Magel- lanic Cloud. Later studies based on deeper photometric 3 data have revised this mass estimate to some 50·10 M⊙ (Brandner et al. 2008, Gennaro et al. 2011, Andersen et al. in prep). Nevertheless, Westerlund 1 is the most mas- sive young cluster known in the Galaxy and it thus offers a unique opportunity to study a supermassive star cluster in a detail impossible for the extragalactic analogues.

Evolved stars

The large population of evolved stars suggests that the cluster is at least 3-4 Myr old. Additional evidence of a slightly evolved cluster is the presence of a neutron star lo- cated only 1.6’ from the cluster center (Muno et al. 2006) which would be a remnant from a previous supernova. Westerlund 1 is an excellent laboratory to study the prop- erties of evolved stars. The rich population of evolved stars allows detailed studies of evolved stars that are all of similar ages. Clark et al. (2005) determined the age of the cluster from the massive star forming content to be 4-5 Myr. Through a thorough campaign identifying target objects through narrow band imaging and follow-up spec- troscopy they found that there is well over 100 stars in the cluster with an initial mass over 30 M⊙, a mass that was also estimated to be the cluster’s turn-off mass. The high mass content spans a large range of spectral classes from Figure 2: An example of the combination of radial veloc- over a dozen WR stars to 25 OB supergiants and 6 yel- low hypergiants. The presence of the hypergiants together ity curves light curves, in this case for the near-contact, double-lined system Wd13 (from Koumpia & Bananos with the red supergiants made Clark et al. (2010) suggest 2012). The current-day masses for the primary and sec- that the transition between the most massive stars and the . . . . less massive stars in the “Conti scheme” (where the high ondary are 32 9 ± 1 9 and 21 1 ± 1 1 M⊙, respectively. mass stars do not evolve through a cool red super-giant phase, see Clark et al. 2010) is above 40 M⊙. The large number of massive stars within a small area Main sequence stars of the sky further allows for more effective studies of the binary properties of massive stars. Photometric variabil- Main sequence stars are much better understood than the ity studies have identified several eclipsing binaries in the bright evolved stars in the cluster, they are still relatively cluster (Bonanos 2007) in addition to many variable stars, easy to observe, and they are rather numerous in Wester- including WR stars and red supergiants. Mass ratios have lund 1. They are therefore well suited to determine the further been determined for the eclipsing binary systems. cluster parameters. Brandner et al. (2008) obtained near- Further studies of the multiplicity among the massive stars infrared imaging and derived photometry of stars from the are carried out with the VLT/FLAMES Westerlund 1 sur- main sequence turn-off down to below 3.4 M⊙ which was vey. Many spectroscopic binaries are discovered in the sur- the completeness limit of the data. Lower mass objects vey which provide strong constraints on the binary prop- were detected but due to crowding only a small fraction erties of massive stars. For example, as shown in Fig. 2, of the cluster members expected to be there were resolved the combination of a radial velocity curve and eclipse mea- and detected. The effect of crowding and the loss of stars surements for the star Wd13 have provided an initial mass were confirmed with artificial star experiments. The study determined the intermediate mass Initial Mass Function of of 40 M⊙ which then sets a lower limit on the origin star of the pulsar in the cluster (Koumpia & Bonanos 2012, the cluster which was found to be well represented by a Richie et al 2010). power-law with a slope close to the Salpeter value. They further found that the cluster is elongated with an eccen- tricity of around 0.2 Gennaro et al. (2011) extended on the work of Brandner

7 et al. and provided more detailed completeness corrections to compensate for crowding while taking the non-spherical shape of Westerlund 1 into account and employing a more elaborate field star subtraction. They found the cluster to be more elongated with an axis ratio of 3 : 2, with the lower-mass objects showing a higher ellipticity than the high mass stars. The origin of the elongation is not clear. The cluster is elongated almost along the Galactic plane, but this may be a coincidence. One possibility could be a merger of two clusters. However, as discussed below, there is no evidence for a large age spread within the cluster, which places rather strict limits on the formation scenarios for such two clusters in that their age difference must have been a Myr or less. The size of Westerlund 1 has been estimated by Lim et al. (2013). Using a larger field of view than the observations Figure 3: J-H color-magnitude diagram of Westerlund in Brandner et al. they estimated a radius of the cluster based on deep J and H band HST data (Andersen et al. in of 2.5’, corresponding to 2.8kpc. prep). The color coding indicate membership probability of each star. Overplotted is a Baraffe et al. (1998) 4 Myr Pre-main sequence stars isochrone shifted to the distance of Westerlund 1 and red- dened by Av = 10.3. The highest mass available for the Based on the age of the cluster it is expected that stars Baraffe et al. isochrone is 1.4 M⊙. The cluster sequence below about 2-3 M⊙ are still in their pre-main sequence continues to higher masses. The red, formally high prob- phase. Reaching these objects is difficult since they are rel- ability, objects at J − H ∼ 2 and H 15 are unrelated field atively faint once both extinction and distance are taken red giants along the line og sight. into account. Further, a combination of the high stel- lar density within the cluster and the presence of the ex- tremely bright supergiants in the cluster precludes identi- tion selected sample of the cluster where the field star con- fication of individual objects with standard ground based tamination is reduced compared to single epoch imaging. observations. Although it was clear from previous ground- They examined whether there is an age spread within the based work that there is a main sequence population, the cluster for the low-mass content. Based on objects close sensitivity and resolution were not sufficient to probe be- to the main sequence/pre-main sequence transition they low around a solar mass, and the completeness of the data deduced that the data were consistent with a rather small was around 3 M⊙. High spatial resolution is necessary, age spread of some 0.4 Myr or less. either with adaptive optics from the ground or with the HST from space. Several current programs are targeting Mass segregation within Westerlund 1 the low-mass content in the cluster. Andersen et al. (in prep) have imaged the cluster with HST/WFC3 over a It was already suspected from the work on the most mas- 4’×4’ (4.8 × 4.8 pc) in order to characterize the Initial sive stars that the cluster is mass segregated, i.e. the mas- Mass function of the cluster down to 0.1 M⊙ outside the sive stars are more centrally concentrated than the aver- most crowded central region. For the first time this al- age stars. The imaging survey by Brandner et al. (2008) lows the peak of the IMF to be identified in a massive star showed that this is true for the stellar population between cluster. The data shows a rich population of pre-main 3.4 and 27 M⊙, the lower mass limit being the complete- sequence stars as shown in Fig. 3. ness limit of their observations. Within the central 0.75 By adopting pre-main sequence evolutionary tracks they pc the slope of the derived mass function was found to be have shown that the IMF in the cluster is close to the field −0.6 compared to a Salpeter slope of −1.35. Conversely, star IMF and the IMF in other star forming regions. This a steeper slope of −1.7 was found between 2.1 and 3.3 places strong constraints on any cluster formation model pc. This was confirmed by Lim et al. (2013) using large that predicts IMF variations as a function of cluster mass. scale optical imaging together with near-infrared imaging. There does not appear to be any discernable mass segre- Kudryavtseva et al. (2012) utilized VLT NAOS/CONICA gation in the lower mass (down to 1 M⊙) stellar content at adaptive optics imaging over a 20” field of view. Together least outside a radius of 0.75 pc. Detecting and obtaining with the later epoch HST data they obtained a proper mo- photometry of low-mass objects within this radius is dif-

8 ficult due to crowding and bright stars. This is a similar stars, particularly at larger radii where the contamination picture of mass segregation as the younger Orion Nebula is substantial. This is especially true for the low-mass star Cluster where the massive stars are mass segregated but and brown dwarf content where field stars are confusing not the low-mass stars. in the color-magnitude diagrams. In addition to provide Gennaro et al. (2011) argue that based on the age and much cleaner samples of cluster members, the proper mo- density of the cluster, the mass segregation of the massive tion samples can be used to derive the velocity dispersion stars can have a dynamical origin and it is not necessary of the cluster members. So far, the optical radial veloc- for the mass segregation to be primordial. ity surveys have been restricted to the high mass content whereas with the proper motion data the low-mass con- The fate of Westerlund 1 tent can be obtained as well. The velocity dispersion for different mass ranges will be a powerful diagnostic of mass Is Westerlund 1 a bound or unbound entity? Due to its segregation in the cluster. mass it could potentially evolve into a low-mass globu- Studies of spectroscopic binaries and variable stars can lar cluster if it is not destroyed due to interactions in the be pushed even further. Near-infrared monitoring provide Galactic disk. Although the three dimensional structure the possibility to identify low-mass eclipsing binaries. The is not currently available, it is possible to determine the large number of pre-main sequence stars in the cluster radial velocity dispersion of the cluster. A single epoch makes it almost guaranteed that many will be present. near-infrared long slit spectroscopy scan of the cluster This will in turn allow dynamical mass ratio estimates of was used for the first attempts to determine the radial binaries within a single cluster over more than an order of velocity dispersion (Mengel et al. 2007). The velocity magnitude in mass within a single cluster, and assuming dispersion based on 4 stars with clear CO band head ab- a single age for the cluster will allow tests of post- and sorption in the K-band was found to be relatively low, pre-main sequence objects at the same time. 5.8 ± 2.1kms−1. Later multi-epoch optical spectroscopy of Finally, the brown-dwarf initial mass function is essentially a sample of bright stars were obtained to place firmer lim- unexplored. Although the present deep HST observations its on the velocity dispersion. One important limitation have discovered brown dwarfs in Westerlund 1, the crowd- of single epoch observations of massive stars in particular ing and contrast precluded any good estimates of their is the high frequency of multiple systems. The relative number density. This will change in the coming years and motion around a binary center of gravity can severely in- for example JWST will easily be able to both image the crease the observed radial velocity dispersion. Cottaar et brown dwarf content and to obtain spectra of individual al. (2012) showed with a sub-set of stars that indeed the objects to ensure they are members and not reddened field velocity dispersion was lower, 2.1+3.3kms−1. For the most −2.1 stars. recent photometric cluster mass estimates they deduced References: that the cluster is sub-virial at the 90% level and they could rule out that the cluster is super-virial at the 97% Andersen, M. et al. in prep. Baraffe, I. et al. 1998, A&A, 337, 403 level. The cluster is therefore expected to be able to sur- Borgman, J., Koornneef, J., & Slingerland, J. 1970, A&A, 4, 248 vive for a long time and could in principle evolve into a Bonanos, A. Z. 2007, AJ, 133, 2696 low-mass globular cluster over time. However, due to its Brandner, W., Clark, J. S., Stolte, A., Waters, R., Negueruela, I., & location in the Galactic plane, it is likely to be dispersed. Goodwin, S. P. 2008, A&A, 478, 137 Brandner, W., Clark, J. S., Stolte, A., et al. 2008, A&A, 478, 137 Encounters with other star clusters and giant molecular Clark, J. S. et al. 2005, A&A, 434, 949 clouds can heat the cluster and it can then easier disperse Clark, J. S., Negueruela, I., Ritchie, B., Crowther, P., & Dougherty, and become a part of the field star population. S. 2010, The Messenger, 142, 31 Clarkson, W. I. et al. 2012, ApJ, 751, 132 Cottaar, M., Meyer, M. R., Andersen, M., & Espinoza, P. 2012, Future studies of Westerlund 1 A&A, 539, A5 Gennaro, M., Brandner, W., Stolte, A., & Henning, T. 2011, MN- Although much has already been learned about Wester- RAS, 412, 2469 lund 1 in the last decade it still holds many secrets that Koumpia, E., & Bonanos, A. Z. 2012, A&A, 547, A30 Kudryavtseva, N. et al. 2012, ApJL, 750, L44 will be revealed in the future. In the coming years it will be Lada, C. J., & Lada, E. A. 2003, ARA&A, 41, 57 possible to obtain proper motions of the individual stars Lim, B., Chun, M.-Y., Sung, H., et al. 2013, AJ, 145, 46 in the cluster in a similar manner to what has been done Mengel, S., & Tacconi-Garman, L. E. 2007, A&A, 466, 151 for NGC 3603 (Rochau et al. 2010) and the Arches clus- Muno, M. P. et al. 2006, ApJL, 636, L41 Ritchie, B. W. et al. 2010, A&A, 520, A48 ter (Clarkson et al. 2011). Unlike the previous study Rochau, B., Brandner, W., Stolte, A., et al. 2010, ApJL, 716, L90 by Kudryavtseva et al., this can now be done for the full Stolte, A., Ghez, A. M., Morris, M., et al. 2008, ApJ, 675, 1278 cluster with the HST. A proper motion selected sample Westerlund, B. 1961, AJ, 66, 57 will help resolve the confusion between cluster and field Westerlund, B. E. 1987, A&AS, 70, 311

9 Abstracts of recently accepted papers

Viscous Evolution and Photoevaporation of Circumstellar Disks due to External FUV Radiation Fields Kassandra R. Anderson1,2, Fred C. Adams1,2 and Nuria Calvet2 1 Physics Department, University of Michigan, Ann Arbor, MI 48109, USA 2 Astronomy Department, University of Michigan, Ann Arbor, MI 48109, USA E-mail contact: kassand at umich.edu This paper explores the effects of FUV radiation fields from external stars on circumstellar disk evolution. Disks residing in young clusters can be exposed to extreme levels of FUV flux from nearby OB stars, and observations show that disks in such environments are being actively photoevaporated. Typical FUV flux levels can be factors of ∼ 102 − 104 higher than the interstellar value. These fields are effective in driving mass loss from circumstellar disks because they act at large radial distance from the host star, i.e., where most of the disk mass is located, and where the gravitational potential well is shallow. We combine viscous evolution (an α-disk model) with an existing FUV photoevaporation model to derive constraints on disk lifetimes, and to determine disk properties as functions of time, including mass loss rates, disk masses, and radii. We also consider the effects of X-ray photoevaporation from the host star using an existing model, and show that for disks around solar-mass stars, externally-generated FUV fields are often the dominant mechanism in depleting disk material. For sufficiently large viscosities, FUV fields can efficiently photoevaporate disks over the entire range of parameter space. Disks with viscosity parameter α = 10−3 are effectively dispersed within 1-3 Myr; for higher viscosities (α = 10−2) disks are dispersed within ∼ 0.25 − 0.5 Myr. Furthermore, disk radii are truncated to less than ∼ 100 AU, which can possibly affect the formation of planets. Our model predictions are consistent with the range of observed masses and radii of proplyds in the Orion Nebula Cluster. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1307.4368v1.pdf

Long-term Evolution of Photoevaporating Protoplanetary Disks Jaehan Bae1, Lee Hartmann1, Zhaohuan Zhu2 and Charles Gammie3,4 1 Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI 48105, USA 2 Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Peyton Hall, Princeton, NJ 08544, USA 3 Department of Astronomy, University of Illinois Urbana-Champaign, 1002 W. Green St., Urbana, IL 61801, USA 4 Department of Physics, University of Illinois Urbana-Champaign, 1110 W. Green St., Urbana, IL 61801, USA E-mail contact: jaehbae at umich.edu We perform calculations of our one-dimensional, two-zone disk model to study the long-term evolution of the circumstel- lar disk. In particular, we adopt published photoevaporation prescriptions and examine whether the photoevaporative loss alone, coupled with a range of initial angular momenta of the protostellar cloud, can explain the observed decline of the frequency of optically-thick dusty disks with increasing age. In the parameter space we explore, disks have < accreting and/or non-accreting transitional phases lasting of ∼20 % of their lifetime, which is in reasonable agreement with observed statistics. Assuming that photoevaporation controls disk clearing, we find that initial angular momen- tum distribution of clouds needs to be weighted in favor of slowly rotating protostellar cloud cores. Again, assuming inner disk dispersal by photoevaporation, we conjecture that this skewed angular momentum distribution is a result of fragmentation into binary or multiple stellar systems in rapidly-rotating cores. Accreting and non-accreting transi- tional disks show different evolutionary paths on the M˙ − Rwall plane, which possibly explains the different observed properties between the two populations. However, we further find that scaling the photoevaporation rates downward by a factor of 10 makes it difficult to clear the disks on the observed timescales, showing that the precise value of the photoevaporative loss is crucial to setting the clearing times. While our results apply only to pure photoevaporative

10 loss (plus disk accretion), there may be implications for models in which planets clear disks preferentially at radii of order 10 AU. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1307.2585

A non-LTE radiative transfer model to study ionized outflows and disks. The case of MWC349A A. B´aez-Rubio1, J. Mart´ın-Pintado1, C. Thum2, and P. Planesas3 1 Centro de Astrobiolog´ıa(CSIC-INTA), Ctra de Torrej´on a Ajalvir, km 4, 28850 Torrej´on de Ardoz, Madrid, Spain 2 Instituto de Radio Astronom´ıaMilim´etrica (IRAM), Avenida Divina Pastora, 7, N´ıucleo Central, E 18012 Granada, Spain 3 Observatorio Astronomico Nacional (IGN), Alfonso XII 3, E-28014 Madrid, Spain E-mail contact: baezra at cab.inta-csic.es Context. The best example of a massive star with an ionized outflow launched from its photoevaporating disk is MWC349A. The large amount of reported radio-continuum and radio-recombination line observations toward this galactic UC-HII region offers a unique possibility to build a model of the ionized envelope of this source. Aims. To understand the physical conditions and kinematics of the ionized region of the circumstellar disk and also of the outflow of MWC349A. Methods. We compared the bulk of radio-continuum maps, radio-recombination line profiles, and the H30α centroid map published to date with the predictions of our non-LTE 3D radiative transfer model, MORELI (MOdel for RE- combination LInes), which we describe here in detail. Results. Our non-LTE 3D radiative transfer model provides new evidence that the UC-HII region of MWC349A is composed of an ionized circumstellar disk rotating in Keplerian fashion around a star of 38 M⊙, and an ionized outflow expanding with a terminal velocity of 60 km s−1 and rotating in the same sense as the disk. The model shows that while maser amplification is the dominant process involved for Hnα radio-recombination line (RRL) emission with quantum numbers n< 41, stimulated emission is relevant for the emission of RRLs with n> 41 up at least the H76α line. Conclusions. For the first time, we present a model of MWC349A which satisfactorily explains the vast amount of reported observational data for a very wide range of frequencies and angular resolutions. Accepted by A&A http://arxiv.org/pdf/1307.3896

Young stellar clusters in the Rosette molecular cloud. Arguments against triggered star formation L. Cambr´esy1, G. Marton2, O. Feher3, L.V. T´oth3, and N. Schneider4 1 Observatoire astronomique de Strasbourg, Universit´ede Strasbourg, CNRS, UMR 7550, 11 rue de l’Universit´e, 67000 Strasbourg, France 2 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Konkoly Thege 15-17, H-1121 Budapest, Hungary 3 E¨otv¨os Lor´and University, Department of Astronomy, P´azm´any P´eter s´et´any 1/A, 1117 Budapest, Hungary 4 Laboratoire d’Astrophysique de Bordeaux, CNRS/INSU, Universit´ede Bordeaux, BP 89, 33271 Floirac cedex, France E-mail contact: cambresy at astro.unistra.fr The Rosette complex is a well studied region of the galactic plane which presents the apparent characteristics of a triggered star forming region. This is however still debated as no strong evidence corroborates this statement. We focus on characterizing the young stellar population in the Rosette complex to improve our understanding of the processes that regulate the star formation in this region. We propose an original method that relies on the joint analysis of the star color and density in the near-infrared. It leads to mapping the molecular cloud spatial distribution and detecting the embedded clusters with their characterization in terms of member number and age estimation. We have identified 13 clusters, 2 of which are new discoveries, and we estimate that the total number of young stellar

11 objects in the Rosette ranges between 4000 and 8000 members. We find that the age distribution of the young clusters is not consistent with a general triggered scenario for the star formation in this molecular cloud. This study proves that the Rosette complex evolution is not governed by the influence of its OB star population. It suggests that the simple morphological appearance of an active region is not sufficient to conclude much about the triggering role in the star formation process. Our method of constraining the cluster properties using UKIDSS and WISE data has proven efficient, and studies of other regions of the galactic plane would definitely benefit from this approach. Accepted by A&A http://arxiv.org/pdf/1307.4756

CEN34 – High-Mass YSO in M17 or Background Post-AGB Star? Zhiwei Chen1,2,3, Dieter N¨urnberger2, Rolf Chini2,4, Yao Liu1, Min Fang1, and Zhibo Jiang1 1 Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, 210008 Nanjing, China 2 Astronomisches Institut, RuhrUniversit¨at Bochum, Universit¨atsstrasse 150, 44801 Bochum, Germany 3 University of Chinese Academy of Sciences, 100039 Beijing, China 4 Instituto de Astronom´ıa, Universidad Cat´olica del Norte, Avenida Angamos 0610, Casilla 1280 Antofagasta, Chile E-mail contact: zwchen at pmo.ac.cn We investigate the proposed high-mass young stellar object (YSO) candidate CEN34, thought to be associated with the star forming region M17. Its optical to near-infrared (550–2500 nm) spectrum reveals several photospheric absorption features, such as Hα, Ca triplet and CO bandheads but lacks any emission lines. The spectral features in the range 8375–8770 A˚ are used to constrain an effective temperature of 5250±250 (early-/mid-G) and a surface gravity of 2.0±0.3 (supergiant). The spectral energy distribution of CEN34 resembles the SED of a high-mass YSO or an evolved star. Moreover, the observed temperature and surface gravity are identical for high-mass YSOs and evolved stars. The radial velocity relative to LSR (VLSR) of CEN34 as obtained from various photospheric lines is of the order of −60 km s−1 and thus distinct from the +25 km s−1 found for several OB stars in the cluster and for the −4 associated molecular cloud. The SED modeling yields ∼ 10 M⊙ of circumstellar material which contributes only a tiny fraction to the total visual extinction (11 mag). In the case of a YSO, a dynamical ejection process is proposed to explain the VLSR difference between CEN34 and M17. Additionally, to match the temperature and luminosity, we −3 −1 speculate that CEN34 had accumulated the bulk of its mass with accretion rate > 4 × 10 M⊙ yr in a very short time span (∼103 yrs), and currently undergoes a phase of gravitational contraction without any further mass gain. However, all the aforementioned characteristics of CEN34 are compatible with an evolved star of 5–7 M⊙ and an age of 50–100 Myrs, most likely a background post-AGB star with a distance between 2.0 kpc and 4.5 kpc. We consider the latter classification as the more likely interpretation. Further discrimination between the two possible scenarios should come from the more strict confinement of CEN34’s distance. Accepted by A&A http://arxiv.org/pdf/1307.3128

Stellar and circumstellar properties of visual binaries in the Orion Nebula Cluster S. Correia1,2, G. Duchˆene3,4, B. Reipurth5,6, H. Zinnecker1,7,8, S. Daemgen9,10, M. G. Petr-Gotzens9, R. K¨ohler11,12, Th. Ratzka13, C. Aspin5, Q. M. Konopacky14 and A. M. Ghez15,16 1 Leibniz-Institut f¨ur Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany 2 Institute for Astronomy, University of Hawaii, 34 Ohia Ku Street, Pukalani, HI 96768, USA 3 Astronomy Department, University of California, Berkeley, CA 94720-3411, USA 4 UJF-Grenoble 1/CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble UMR 5274, 38041 Grenoble, France 5 Institute for Astronomy, University of Hawaii, 640 N. Aohoku Place, Hilo, HI 96720, USA 6 NASA Astrobiology Institute 7 Deutsches SOFIA Institut, Universit¨at Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart, Germany 8 SOFIA Science Center, NASA-Ames Research Center, MS 232-12, Moffett Field, CA 94035, USA 9 European Southern Observatory, Karl Schwartzschild Str. 2, 85748 Garching bei M¨unchen, Germany

12 10 Department of Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada 11 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69117 Heidelberg, Germany 12 Landessternwarte, Zentrum f¨ur Astronomie der Universit¨at Heidelberg, K¨onigstuhl, 69117 Heidelberg, Germany 13 Universit¨ats-Sternwarte M¨unchen, Ludwig-Maximilians-Universit¨at, Scheinerstr. 1, 81679 M¨unchen, Germany 14 Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto M5S 3H4, Ontario, Canada 15 Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547, USA 16 Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, CA 90095-1565, USA E-mail contact: sergeco at gmail.com Our general understanding of multiple star and planet formation is primarily based on observations of young multiple systems in low density regions like Tau-Aur and Oph. Since many, if not most, of the stars are born in clusters, observational constraints from young binaries in those environments are fundamental for understanding both the formation of multiple systems and planets in multiple systems throughout the Galaxy. We build upon the largest survey for young binaries in the Orion Nebula Cluster (ONC) which is based on Hubble Space Telescope observations to derive both stellar and circumstellar properties of newborn binary systems in this cluster environment. We present Adaptive Optics spatially-resolved JHKL’-band photometry and K-band R∼ 5000 spectra for a sample of 8 ONC binary systems from this database. We characterize the stellar properties of binary components and obtain a census of protoplanetary disks through K-L’ color excess. For a combined sample of ONC binaries including 7 additional systems with NIR spectroscopy from the literature, we derive mass ratio and relative age distributions. We compare the stellar and circumstellar properties of binaries in ONC with those in Tau-Aur and Oph from samples of binaries with stellar properties derived for each component from spectra and/or visual photometry and with a disk census obtained through K-L color excess. The mass ratio distribution of ONC binaries is found to be indistinguishable from that of Tau-Aur and, to some extent, to that of Oph in the separation range 85-560AU and for primary mass in the range 0.15 to 0.8 M⊙. A trend toward a lower mass ratio with larger separation is suggested in ONC binaries which is not seen in Tau-Aur binaries. The components of ONC binaries are found to be significantly more coeval than the overall ONC population and as coeval as components of binaries in Tau-Aur and Oph. There is a hint of a larger fraction of mixed pairs, i.e. systems with a disk around only one component, in wide ONC binaries in comparison to wide binaries in Tau-Aur and Oph within the same primary mass range that could be caused by hierarchical triples. The mass ratio distributions of mixed and unmixed pairs in the overall population of T Tauri binaries are shown to be different. Some of these trends require confirmation with observations of a larger sample of binary systems. Accepted by A&A http://arxiv.org/pdf/1307.2299v1.pdf

Berkeley 94 and Berkeley 96: Two Young Clusters with Different Dynamical Evolution A.J. Delgado1, A.A Djupvik2, M.T. Costado1 and E.J. Alfaro1 1 Instituto de Astrof´ısica de Andaluc´ıa(IAA-CSIC), Glorieta de la Astronom´ıa, 18008-Granada, Spain 2 Nordic Optical Telescope (NOT), Apdo. 474, 38700 Santa Cruz de La Palma, Spain. E-mail contact: delgado at iaa.es We have performed multiband UBVRcIcJHKs photometry of two young clusters located at large Galactocentric distances in the direction of the Perseus spiral arm. The obtained distances and colour excesses amount to 3.9±0.11 kpc, E(B − V )=0.62±0.05 for Berkeley 94, and 4.3±0.15 kpc, E(B − V )=0.58±0.06 for Berkeley 96. The respective ages, as measured from the comparison of the upper colour-magnitude diagrams to model isochrones, amount to log10Age(yr)=7.5±0.07, and 7.0±0.07, respectively. A sequence of optical PMS members is proposed in both clusters. In addition, samples of objects showing (H − Ks) excess are found. Part of these are suggested to be PMS cluster members of lower mass than the optical candidates. The spatial distribution of these sources, the comparison to galactic models and to the expected number of contaminating distant red galaxies, and the spectral energy distribution in particular cases support this suggestion. According to the results from numerical simulations, the spatial distributions of members in different mass ranges are interpreted as suggesting different initial conditions and evolutionary dynamical paths for the clusters. Berkeley 94 would have formed under supervirial conditions, and followed the so-called warm collapse model in its evolution, whereas Berkeley 96 would have formed with a subvirial structure, and would have

13 evolved following a cold collapse path. Both processes would be able to reproduce the suggested degree of mass segregation and their spatial distribution by mass range. Finally, the mass distributions of the clusters, from the most massive stars down to PMS stars around 1.3 M⊙, are calculated. An acceptable general agreement with the Salpeter IMF slope is found. Accepted by MNRAS http://arxiv.org/pdf/1307.4290

Photometric determination of the mass accretion rates of pre-main sequence stars. IV. Recent star formation in NGC 602 Guido De Marchi1, Giacomo Beccari2 and Nino Panagia3,4,5 1 European Space Agency, Keplerlaan 1, 2200 AG Noordwijk, Netherlands 2 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany 3 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 4 INAF–NA, Osservatorio Astronomico di Capodimonte, Salita Moiariello, 16 80131 Naples, Italy 5 Supernova Limited, OYV #131, Northsound Rd., Virgin Gorda, British Virgin Islands, VG 1155 E-mail contact: gdemarchi at rssd.esa.int We have studied the young stellar populations in NGC 602, in the Small Magellanic Cloud, using a novel method that we have developed to combine Hubble Space Telescope photometry in the V , I, and Hα bands. We have identified about 300 pre-main sequence (PMS) stars, all of which are still undergoing active mass accretion, and have determined their physical parameters (effective temperature, luminosity, age, mass and mass accretion rate). Our analysis shows that star formation has been present in this field over the last 60 Myr. In addition, we can recognise at least two clear, distinct, and prominent episodes in the recent past: one about 2 Myr ago, but still ongoing in regions of higher nebulosity, and one (or more) older than 30 Myr, encompassing both stars dispersed in the field and two smaller clusters located about 100 arcsec north of the centre of NGC602. The relative locations of younger and older PMS stars do not imply a causal effect or triggering of one generation on the other. The strength of the two episodes appears to be comparable, but the episode occurring more than 30 Myr ago might have been even stronger than the current one. We have investigated the evolution of the mass accretion rate M˙ acc as a function of the stellar parameters finding that log M˙ acc ≃−0.6 log t + log m + c, where t is the age of the star, m its mass and c is a decreasing function of the metallicity. Accepted by Astrophys. J. http://arxiv.org/pdf/1307.8445

Pre-main sequence stars older than 8 Myr in the Eagle Nebula Guido De Marchi1, Nino Panagia2,3,4, M. G. Guarcello5 and Rosaria Bonito6 1 European Space Agency, Keplerlaan 1, 2200 AG Noordwijk, 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, British Virgin Islands, VG 1155 5 Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA 6 Dipartimento di Fisica e Chimica, Universit`adi Palermo and INAF–PA, Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy E-mail contact: gdemarchi at rssd.esa.int Attention is given to a population of 110 stars in the NGC 6611 cluster of the Eagle Nebula that have prominent near-infrared (NIR) excess and optical colours typical of pre-main sequence (PMS) stars older than 8Myr. At least half of those for which spectroscopy exists have a Hα emission line profile revealing active accretion. In principle, the V − I colours of all these stars would be consistent with those of young PMS objects (< 1 Myr) whose radiation is heavily obscured by a circumstellar disc seen at high inclination and in small part scattered towards the observer by the back side of the disc. However, using theoretical models it is shown here that objects of this type can only account for a few percent of this population. In fact, the spatial distribution of these objects, their X-ray luminosities,

14 their optical brightness, their positions in the colour–magnitude diagram and the weak Li absorption lines of the stars studied spectroscopically suggest that most of them are at least 8 times older than the ∼ 1Myr-old PMS stars already known in this cluster and could be as old as ∼ 30 Myr. This is the largest homogeneous sample to date of Galactic PMS stars considerably older than 8 Myr that are still actively accreting from a circumstellar disc and it allows us to set a lower limit of 7 % to the disc frequency at ∼ 16 Myr in NGC 6611. These values imply a characteristic exponential lifetime of ∼ 6 Myr for disc dissipation. Accepted by MNRAS http://arxiv.org/pdf/1307.8446

DIGIT: Herschel and Spitzer spectro-imaging of SMM3 and SMM4 in Serpens O. Dionatos1,2,3, J. K. Jørgensen 2,1, J. D. Green4, G. J. Herczeg5, N. J. Evans II 4, L. E. Kristensen6, J. E. Lindberg1,2 and E. F. van Dishoeck 6,7 1 Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5 – 7, DK-1350 Copenhagen K. Denmark 2 Niels Bohr Institute, University of Copenhagen. Juliane Maries Vej 30, DK-2100 Copenhagen Ø. Denmark 3 University of Vienna, Department of Astronomy, T¨urkenschanzstrasse 17, A-1180, Vienna, Austria 4 University of Texas at Austin, Department of Astronomy, 2515 Speedway, Stop C1400, Austin, TX 78712-1205, USA 5 Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, 100871, PR China 6 Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden, The Netherlands 7 Max Planck Institut f¨ur Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching, Germany E-mail contact: odysseas at nbi.ku.dk We report on spectro-imaging observations employing Spitzer/IRS and Herschel/PACS, aiming to constrain the phys- ical conditions around SMM3 and SMM4 in Serpens. The combined power of both instruments provides an almost complete wavelength coverage between 5 and 200 µm at an angular resolution of 10”. We detect line emission from all major molecular (H2, CO, H2O and OH) and many atomic ([OI], [CII], [FeII], [SiII] and [SI]) coolants. Line emission tends to peak at distances of 10” - 20” from the protostellar sources, at positions of known outflow shocks. The only exception is [CII] which likely traces a PDR excited from the neighboring source SMM6. Excitation analysis indicates that H2 and CO originate from gas at two distinct rotational temperatures of 300 K and 1000 K, while H2O and OH emission corresponds to rotational temperatures of 100 - 200 K. The morphological and physical association between CO and H2 suggests a common excitation mechanism which allows direct comparisons between the two molecules. −5 −4 The CO/H2 abundance ratio varies from 10 in the warm gas up to 10 in the hotter regions. While both C- and J-shocks can account for the observed molecular emission, J-shocks are strongly advocated by the atomic emission and line ratio diagnostics that provide simpler and more homogeneous solutions for the excitation of CO and H2. C-shocks describe better the emission from H2O and OH. The variations in the CO/H2 abundance ratio for gas at different temperatures can be interpreted by their reformation rates in dissociative J-type shocks, or the simultaneous influence of both C and J shocks. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1307.2726

Planetesimal formation via sweep-up growth at the inner edge of dead zones Joanna Dra˙zkowska1,2, Fredrik Windmark1,2 and Cornelis P. Dullemond1 1 Heidelberg University, Center for Astronomy, Institute for Theoretical Astrophysics, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany 2 Member of the International Max Planck Research School for Astronomy and Astrophysics at the Heidelberg Uni- versity E-mail contact: drazkowska at uni-heidelberg.de The early stages of planet formation are still not well understood. Coagulation models have revealed numerous obstacles to the dust growth, such as the bouncing, fragmentation and radial drift barriers. We study the interplay between dust coagulation and drift in order to determine the conditions in protoplanetary disk that support the

15 formation of planetesimals. We focus on planetesimal formation via sweep-up and investigate whether it can take place in a realistic protoplanetary disk. We have developed a new numerical model that resolves spatial distribution of dust in the radial and vertical dimension. The model uses representative particles approach to follow the dust evolution in protoplanetary disk. The coagulation and fragmentation of solids is taken into account using Monte Carlo method. A collision model adopting the mass transfer effect, that can occur for different-sized dust aggregate collisions, is implemented. We focus on a protoplanetary disk including a pressure bump caused by a steep decline of turbulent viscosity around the snow line. Our results show that sufficient resolution of the vertical disk structure in dust coagulation codes is necessary to obtain adequately short growth timescales, especially in the case of a low turbulence region. We find that a sharp radial variation of the turbulence strength at the inner edge of dead zone promotes planetesimal formation in several ways. It provides a pressure bump that efficiently prevents the dust from drifting inwards. It also causes a radial variation in the size of aggregates at which growth barriers occur, favoring the growth of large aggregates via sweeping up of small particles. In our model, by employing an ad hoc alpha viscosity change near the snow line, it is possible to grow planetesimals by incremental growth on timescales of approximately 105 years. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1306.3412

The Gould’s Belt Very Large Array Survey I: The Ophiuchus complex Sergio Dzib1, Laurent Loinard1,2, Amy J. Mioduszewski3, Luis F. Rodr´ıguez1,4, Gisela N. Ortiz-Le´on1, Gerardo Pech1, Juana L. Rivera1, Rosa M. Torres5, Andrew F. Boden6, Lee Hartmann7, Neal J. Evans II8, Cesar Brice˜no9 and John Tobin10 1 Centro de Radioastronom´ıay Astrof´ısica, Universidad Nacional Aut´onoma de M´exico Apartado Postal 3-72, 58090, Morelia, Michoac´an, Mexico 2 Max Planck Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, 53121 Bonn, Germany 3 National Radio Astronomy Observatory, Domenici Science Operations Center, 1003 Lopezville Road, Socorro, NM 87801, USA 4 King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia 5 Paul Harris 9065, Las Condes, Santiago, Chile 6 Division of Physics, Math, and Astronomy, California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125, USA 7 Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105, USA 8 Department of Astronomy, The University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712, USA 9 Centro de Investigaciones de Astronom´ıa, M´erida 5101-A, Venezuela 10 National Radio Astronomy Observatory, Charlottesville, VA 22903 E-mail contact: s.dzib at crya.unam.mx We present large-scale (∼ 2000 square arcminutes), deep (∼ 20 µJy), high-resolution (∼ 1′′) radio observations of the Ophiuchus star-forming complex obtained with the Karl G. Jansky Very Large Array at λ = 4 and 6 cm. In total, 189 sources were detected, 56 of them associated with known young stellar sources, and 4 with known extragalactic objects; the other 129 remain unclassified, but most of them are most probably background quasars. The vast majority of the young stars detected at radio wavelengths have spectral types K or M, although we also detect 4 objects of A/F/B types and 2 brown dwarf candidates. At least half of these young stars are non-thermal (gyrosynchrotron) sources, with active coronas characterized by high levels of variability, negative spectral indices, and (in some cases) significant circular polarization. As expected, there is a clear tendency for the fraction of non-thermal sources to increase from the younger (Class 0/I or flat spectrum) to the more evolved (Class III or weak line T Tauri) stars. The young stars detected both in X-rays and at radio wavelengths broadly follow a G¨udel-Benz relation, but with a different normalization than the most radio-active types of stars. Finally, we detect a ∼ 70 mJy compact extragalactic source near the center of the Ophiuchus core, which should be used as gain calibrator for any future radio observations of this region. Accepted by ApJ http://arxiv.org/pdf/1307.5105

16 Herschel observations of the Sgr B2 cores: Hydrides, warm CO, and cold dust M. Etxaluze1, J.R. Goicoechea1, J. Cernicharo1, E.T. Polehampton2,3, A. Noriega-Crespo4, S. Molinari5, B.M. Swinyard2,6, R. Wu7 , and J. Bally8 1 Departamento de Astrof´ısica. Centro de Astrobiolog´ıa. CSIC-INTA. Torrej´on de Ardoz, 28850 Madrid, Spain 2 RAL Space, Rutherford Appleton Laboratory, Oxfordshire, OX11 0QX, UK 3 Institute for Space Imaging Science, Department of Physics & Astronomy, University of Lethbridge, Lethbridge, AB T1K3M4, Canada 4 Spitzer Science Center, 91125 Pasadena, USA 5 INAF-IFSI, I-00133 Roma, Italy 6 Dept. of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK 7 Commissariat A´ l’Energie´ Atomique, Service d’Astrophysique, Saclay, 91191 ‘ Gif-sur-Yvette, France 8 CASA, University of Colorado, Boulder, USA 80309 E-mail contact: etxaluzeam at cab.inta-csic.es Sagittarius B2 (Sgr B2) is one of the most massive and luminous star-forming regions in the Galaxy and shows chemical and physical conditions similar to those in distant extragalactic starbursts. We present large-scale far-IR/submm photometric images and spectroscopic maps taken with the PACS and SPIRE instruments onboard Herschel. The spectra towards the Sgr B2 star-forming cores, B2(M) and B2(N), are characterized by strong CO line emission, + emission lines from high-density tracers (HCN, HCO , and H2S), [N II] 205 µm emission from ionized gas, and + + + + absorption lines from hydride molecules (OH , H2O , H2O, CH , CH, SH , HF, NH, NH2, and NH3). The rotational population diagrams of CO suggest the presence of two gas temperature components: an extended warm component, which is associated with the extended envelope, and a hotter component, which is seen towards the B2(M) and B2(N) cores. As observed in other Galactic Center clouds, the gas temperatures are significantly higher than the dust temperatures inferred from photometric images. We determined far-IR and total dust masses in the cores. Non-local thermodynamic equilibrium models of the CO excitation were used to constrain the averaged gas density in the cores. A uniform luminosity ratio is measured along the extended envelope, suggesting that the same mechanism dominates the heating of the molecular gas at large scales. The detection of high-density molecular tracers and of strong [N II] 205 µm line emission towards the cores suggests that their morphology must be clumpy to allow UV radiation to escape from the inner HII regions. Together with shocks, the strong UV radiation field is likely responsible for the heating of the hot CO component. At larger scales, photodissociation regions models can explain both the observed CO line ratios and the uniform L(CO)/LFIR luminosity ratios. Accepted by A&A http://arxiv.org/pdf/1307.0335

Bipolar jets launched from accretion disks. II. Formation of asymmetric jets and counter jets Christian Fendt1 and Somayeh Sheikhnezami1 1 Max Planck Institute for Astronomy, Heidelberg, Germany E-mail contact: fendt at mpia.de We investigate the jet launching from accretion disks, in particular the formation of intrinsically asymmetric jet / counter-jet systems. We perform axisymmetric MHD simulations of the disk-jet structure on a bipolar computational domain covering both hemispheres. We apply various models such as: asymmetric disks with (initially) different scale height in each hemisphere; symmetric disks into which a local disturbance is injected; and jets launched into an asymmetric disk corona. We consider both a standard global magnetic diffusivity distribution and a novel local diffusivity model. Typical disk evolution first shows substantial disk warping and then results in asymmetric outflows with 10- 30% mass flux difference. We find that the magnetic diffusivity profile is essential for establishing a long- term outflow asymmetry. We conclude that bipolar asymmetry in protostellar and extra-galactic jets can indeed be generated intrinsically and maintained over long time by disk asymmetries and the standard jet launching mechanism. Accepted by ApJ

17 Diffuse Molecular Cloud Densities from UV Measurements of CO Absorption Paul Goldsmith1 1Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena CA 91109, USA E-mail contact: paul.f.goldsmith at jpl.nasa.gov We use UV measurements of interstellar CO towards nearby stars to calculate the density in the diffuse molecular clouds containing the molecules responsible for the observed absorption. Chemical models and recent calculations of the excitation rate coefficients indicate that the regions in which CO is found have hydrogen predominantly in molecular form. We carry out statistical equilibrium calculations using CO–H2 collision rates to solve for the H2 density in the observed sources without including effects of radiative trapping. We have assumed kinetic temperatures of 50 K and 100 K, finding this choice to make relatively little difference to the lowest transition. For the sources having ex −3 T10 only, for which we could determine upper and lower density limits, we find = 49 cm . While we can find a consistent density range for a good fraction of the sources having either two or three values of the excitation temperature, there is a suggestion that the higher–J transitions are sampling clouds or regions within diffuse molecular cloud material that have higher densities than the material sampled by the J = 1–0 transition. The assumed kinetic temperature and derived H2 density are anticorrelated when the J = 2–1 transition data, the J = 3–2 transition data, or both are included. For sources with either two or three values of the excitation temperature, we find average values of the midpoint of the density range that is consistent with all of the observations equal to 68 cm−3 for T k = 100 K and 92 cm−3 for T k = 50 K. The data for this set of sources imply that diffuse molecular clouds are characterized by an average thermal pressure between 4600 and 6800 Kcm−3. Accepted by The Astrophysical Journal

Do Giant Planets Survive Type II Migration? Yasuhiro Hasegawa1 and Shigeru Ida2 1 Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), Taipei 10641, Taiwan 2 Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, 152-8551, Japan E-mail contact: yasu at asiaa.sinica.edu.tw Planetary migration is one of the most serious problems to systematically understand the observations of exoplanets. We clarify that the theoretically predicted type II migration is too fast, as well as type I migration, by developing detailed analytical arguments in which the timescale of type II migration is compared with the disk lifetime. In the disk-dominated regime, the type II migration timescale is characterized by a local viscous diffusion timescale, while the disk lifetime characterized by a global diffusion timescale that is much longer than the local one. Even in the planet- dominated regime where the inertia of the planet mass reduces the migration speed, the timescale is still shorter than the disk lifetime except in the final disk evolution stage where the total disk mass decays below the planet mass. This suggests that most giant planets plunge into the central stars within the disk lifetime, and it contradicts the exoplanet > observations that gas giants are piled up at r∼1AU. We examine additional processes that may arise in protoplanetary disks: dead zones, photoevaporation of gas, and gas flow across a gap formed by a type II migrator. Although they make the type II migration timescale closer to the disk lifetime, we show that none of them can act as an effective barrier for rapid type II migration with the current knowledge of these processes. We point out that gas flow across a gap and the fraction of the flow accreted onto the planets are uncertain and they may have a potential to solve the problem. Much more detailed investigation for each process may be needed to explain the observed distribution of gas giants in extrasolar planetary systems. Accepted by ApJ http://arxiv.org/pdf/1307.4811

Survival of interstellar molecules to prestellar dense core collapse and early phases of disk formation Ugo Hincelin1, Valentine Wakelam2,3, Benoit Commercon4, Franck Hersant2,3 and Stephane Guilloteau2,3 1 Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA 2 Univ. Bordeaux, LAB, UMR 5804, F-33270, Floirac, France

18 3 CNRS, LAB, UMR 5804, F-33270, Floirac, France 4 Laboratoire de radioastronomie, LERMA, Observatoire de Paris, Ecole Normale Superieure (UMR 8112 CNRS), 24 rue Lhomond, 75231 Paris Cedex 05, France E-mail contact: ugo.hincelin at virginia.edu An outstanding question of astrobiology is the link between the chemical composition of planets, comets and other Solar System bodies and the molecules formed in the interstellar medium. Understanding the chemical and physical evolution of the matter leading to the formation of protoplanetary disks is an important step for this. We bring some new stones to this longstanding problem using three-dimensional chemical simulations of the early phases of disk formation: we interfaced the full gas-grain chemical model Nautilus with the radiation-magneto-hydrodynamic model RAMSES, for different configurations and intensities of magnetic field. Our results show that the chemical content (gas and ices) is globally conserved during the collapsing process, from the parent molecular cloud to the young disk surrounding the first Larson core. A qualitative comparison with cometary composition suggests that comets are constituted of different phases, some molecules being direct tracers of interstellar chemistry, while others, including complex molecules, seem to have been formed in disks, where higher densities and temperatures allow for an active grain surface chemistry. The latter phase, and its connection with the formation of the first Larson core, remains to be modelled. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1307.6868v1.pdf

The G305 star-forming complex: radio continuum and molecular line observations L. Hindson1,2,3, M.A. Thompson2, J.S. Urquhart3,7, A. Faimali2, M. Johnston-Hollitt1, J.S. Clark4, B. Davies5,6 1 School of Chemical and Physical Science, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand 2 Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, College Lane, Hateld, AL10 9AB, UK 3 ATNF, CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710, Australia 4 Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK 5 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK 6 School of Physics & Astronomy, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK 7 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, 53121 Bonn, Germany E-mail contact: l.hindson at herts.ac.uk We present 109-115 GHz (3 mm) wide-field spectral line observations of 12CO, 13CO and C18O J = 1–0 molecular emission and 5.5 and 8.8 GHz (6 and 3 cm) radio continuum emission towards the high-mass star forming complex known as G305. The morphology of G305 is dominated by a large evacuated cavity at the centre of the complex driven by clusters of O stars surrounded by molecular gas. Our goals are to determine the physical properties of the molecular environment and reveal the relationship between the molecular and ionised gas and star formation in G305. This is in an effort to characterise the star-forming environment and constrain the star formation history in an attempt to evaluate the impact of high-mass stars on the evolution of the G305 complex. Analysis of CO emission in G305 reveals 156 molecular clumps with the following physical characteristics. The 5.5 and 8.8GHz radio continuum emission reveals an extended low surface brightness ionised environment within which we identify 15 large-scale features with a further eight smaller sources projected within these features. By comparing to mid infrared emission and archival data, we identify nine HII regions, seven compact HII regions, one UC HII region, four extended regions. The total integrated flux of the radio continuum emission at 5.5 GHz is ∼180 Jy corresponding to a Lyman continuum output of 2.4 × 1050 photons s−1. We compare the ionised and molecular environment with optically identified high-mass stars and ongoing star formation, identified from the literature. Analysis of this dataset reveals a star formation rate of 0.008–0.016 and efficiency of 7–12%, allows us to probe the star formation history of the region and discuss the impact of high-mass stars on the evolution of G305. Accepted by MNRAS http://arxiv.org/pdf/1307.6904

19 ALMA Resolves 30 Doradus: Sub-parsec Molecular Cloud Structure Near the Closest Super-Star Cluster R´emy Indebetouw1,2, Crystal Brogan1, C.-H. Rosie Chen3, Adam Leroy1, Kelsey Johnson2, Erik Muller4, Suzanne Madden5, Diane Cormier6, Fr´ed´eric Galliano5, Annie Hughes7, Todd Hunter1, Akiko Kawamura4, Amanda Kepley1, Vianney Lebouteiller5, Margaret Meixner8, Joana M. Oliveira9, Toshikazu Onishi10, Tatiana Vasyunina11 1 National Radio Astronomy Observatory, 520 Edgemont Road Charlottesville, VA 22903, USA 2 Department of Astronomy, University of Virginia, P.O. Box 3818, Charlottesville, VA 22903-0818, USA 3 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, D-53121, Bonn, Germany 4 ALMA-J Project Office, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 5 Service dAstrophysique, Commissariat ´aLEnergie´ Atomique de Saclay, 91191 Gif-sur-Yvette, France 6 Institut f¨ur theoretische Astrophysik, Zentrum f¨ur Astronomie der Universit¨at Heidelberg, Albert-Ueberle Str. 2, D-69120 Heidelberg, Germany 7 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, D-69117, Heidelberg, Germany 8 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 9 School of Physical and Geographical Sciences, Lennard-Jones Laboratories, Keele University, Staordshire ST5 5BG, UK 10 Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan 11 Department of Chemistry, University of Virginia, Charlottesville, VA 22903, USA E-mail contact: rindebet at nrao.edu We present ALMA observations of 30 Doradus – the highest resolution view of molecular gas in an extragalactic star formation region to date (∼0.4pc × 0.6pc). The 30Dor-10 cloud north of R136 was mapped in 12CO 2–1, 13 18 12 CO 2–1, C O 2–1, 1.3mm continuum, the H30α recombination line, and two H2CO 3–2 transitions. Most CO emission is associated with small filaments and clumps (<1pc, ∼1000 M⊙ at the current resolution). Some clumps are associated with protostars, including ”pillars of creation” photoablated by intense radiation from R136. Emission from molecular clouds is often analyzed by decomposition into approximately beam-sized clumps. Such clumps in 30 Doradus follow similar trends in size, linewidth, and surface density to Milky Way clumps. The 30 Doradus clumps have somewhat larger linewidths for a given size than predicted by Larson’s scaling relation, consistent with pressure confinement. They extend to higher surface density at a given size and linewidth compared to clouds studied at 10pc resolution. These trends are also true of clumps in Galactic infrared-dark clouds; higher resolution observations of both environments are required. Consistency of clump masses calculated from dust continuum, CO, and the virial theorem reveals that the CO abundance in 30 Doradus clumps is not significantly different from the LMC mean, but the dust abundance may be reduced by ∼2. There are no strong trends in clump properties with distance from R136; dense clumps are not strongly affected by the external radiation field, but there is a modest trend towards lower dense clump filling fraction deeper in the cloud. Accepted by ApJ http://arxiv.org/pdf/1307.3680

An azimuthal asymmetry in the LkHα 330 disk Andrea Isella1, Laura M. P´erez2, John M. Carpenter3, Luca Ricci3, Sean Andrews4, and Katherine Rosenfeld4 1 Department of Astronomy, California Institute of Technology, MC 249-17, Pasadena, CA 91125, USA 2 Jansky fellow, NRAO, Socorro, NM, USA 3 Department of Astronomy, California Institute of Technology, MC 249-17, Pasadena, CA 91125, USA 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA E-mail contact: isella at astro.caltech.edu Theory predicts that giant planets and low mass stellar companions shape circumstellar disks by opening annular gaps in the gas and dust spatial distribution. For more than a decade it has been debated whether this is the dominant process that leads to the formation of transitional disks. In this paper, we present millimeter-wave interferometric

20 observations of the transitional disk around the young intermediate mass star LkHα 330. These observations reveal a lopsided ring in the 1.3 mm dust thermal emission characterized by a radius of about 100 AU and an azimuthal intensity variation of a factor of 2. By comparing the observations with a Gaussian parametric model, we find that the observed asymmetry is consistent with a circular arc, that extends azimuthally by about 90◦ and emits about 1/3 of the total continuum flux at 1.3 mm. Hydrodynamic simulations show that this structure is similar to the azimuthal asymmetries in the disk surface density that might be produced by the dynamical interaction with unseen low mass companions orbiting within 70 AU from the central star. We argue that such asymmetries might lead to azimuthal variations in the millimeter-wave dust opacity and in the dust temperature, which will also affect the millimeter- wave continuum emission. Alternative explanations for the observed asymmetry that do not require the presence of companions cannot be ruled out with the existing data. Further observations of both the dust and molecular gas emission are required to derive firm conclusions on the origin of the asymmetry observed in the LkHα 330 disk. Accepted by ApJ http://arxiv.org/pdf/1307.5848

A Multiplicity Census of Intermediate-Mass Stars in Scorpius-Centaurus Markus Janson1,8, David Lafreni´ere2, Ray Jayawardhana3 , Mariangela Bonavita3,4, Julien H. Girard5, Alexis Brandeker6, John E. Gizis7 1 Department of Astrophysical Sciences, Princeton University, Princeton, NJ, USA 2 Department of Physics, University of Montreal, Montreal, QC, Canada 3 Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON, Canada 4 Osservatorio Astronomico di Padova - INAF, Padova, Italy 5 European Southern Observatory, Santiago, Chile 6 Department of Astronomy, Stockholm University, Stockholm, Sweden 7 Department of Physics and Astronomy, University of Delaware, Newark, DE, USA 8 Hubble fellow E-mail contact: janson at astro.princeton.edu Stellar multiplicity properties have been studied for much of the range from the lowest to the highest stellar masses, but intermediate-mass stars from F-type to late A-type have received relatively little attention. Here we report on a Gemini/NICI snapshot imaging survey of 138 such stars in the young Scorpius-Centaurus (Sco-Cen) region, for the purpose of studying multiplicity with sensitivity down to planetary masses at wide separations. In addition to two brown dwarfs and a companion straddling the hydrogen burning limit we reported previously, here we present 26 new stellar companions and determine a multiplicity fraction within 0′′. 1–5′′. 0 of 21±4%. Depending on the adopted semi-major axis distribution, our results imply a total multiplicity in the range of ∼60–80%, which further supports the known trend of a smoothly continuous increase in the multiplicity fraction as a function of primary stellar mass. A surprising feature in the sample is a distinct lack of nearly equal-mass binaries, for which we discuss possible reasons. The survey yielded no additional companions below or near the deuterium-burning limit, implying that their frequency at >200 AU separations is not quite as high as might be inferred from previous detections of such objects within the Sco-Cen region. Accepted by ApJ http://arxiv.org/pdf/1307.2243

Modelling Carbon Radio Recombination Line observation towards the Ultra-Compact H ii region W48A S. Jeyakumar1,3 and D. Anish Roshi2 1 Departamento de Astronom´ıa, Universidad de Guanajuato, AP 144, Guanajuato CP 36000, Mexico 2 National Radio Astronomy Observatory, Charlottesville, VA 22903-4608, USA 3 Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore - 560 080, India E-mail contact: sjk at astro.ugto.mx We model Carbon Recombination Line (CRL) emission from the Photo Dissociation Region (PDR) surrounding the

21 Ultra-Compact (UC) H ii region W48A. Our modelling shows that the inner regions (AV ∼ 1) of the C ii layer in the PDR contribute significantly to the CRL emission. The dependence of line ratios of CRL emission with the density of the PDR and the far ultra-violet (FUV) radiation incident on the region is explored over a large range of these parameters that are typical for the environments of UCH ii regions. We find that by observing a suitable set of CRLs it is possible to constrain the density of the PDR. If the neutral density in the PDR is high (≥ 107 cm−3 ) CRL emission is bright at high frequencies (≥ 20 GHz), and absorption lines from such regions can be detected at low frequencies (≤ 10 GHz). Modelling CRL observations towards W48A shows that the UCH ii region is embedded in a molecular cloud of density of about 4 × 107 cm−3 . Accepted by MNRAS

Large-scale mapping of the massive star-forming region RCW38 in the [CII] and PAH emission H. Kaneda1, T. Nakagawa2, S.K. Ghosh3, D.K. Ojha3, D. Ishihara1, T. Kondo1, J.P. Ninan3,M. Tanabe1, Y. Fukui1, Y. Hattori1, T. Onaka4, K. Torii1, and M. Yamagishi1 1 Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan 2 Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252- 5210, Japan 3 Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India 4 Department of Astronomy, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan E-mail contact: kaneda at u.phys.nagoya-u.ac.jp We investigate the large-scale structure of the interstellar medium (ISM) around the massive star cluster RCW 38 in the [CII] 158 µm line and polycyclic aromatic hydrocarbon (PAH) emission. We carried out [CII] line mapping of an area of ∼30′ × 15′ for RCW 38 by a Fabry-Perot spectrometer on a 100 cm balloon-borne telescope with an angular resolution of ∼1.′5. We compared the [CII] intensity map with the PAH and dust emission maps obtained by the AKARI satellite. The [CII] emission shows a highly nonuniform distribution around the cluster, exhibiting the structure widely extended to the north and the east from the center. The [CII] intensity rapidly drops toward the southwest direction, where a CO cloud appears to dominate. We decompose the 3–160 µm spectral energy distributions of the surrounding ISM structure into PAH as well as warm and cool dust components with the help of 2.5–5 µm spectra. We find that the [CII] emission spatially corresponds to the PAH emission better than to the dust emission, confirming the relative importance of PAHs for photo-electric heating of gas in photo-dissociation regions. A naive interpretation based on our observational results indicates that molecular clouds associated with RCW38 are located both on the side of and behind the cluster. Accepted by A&A http://arxiv.org/pdf/1307.0263

Fluffy dust forms icy planetesimals by static compression Akimasa Kataoka1,2, Hidekazu Tanaka3, Satoshi Okuzumi4, and Koji Wada5 1 Department of Astronomical Science, School of Physical Sciences, Graduate University for Advanced Studies (SO- KENDAI), Mitaka, Tokyo 181-8588, Japan 2 National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan 3 Institute of Low Temperature Science, Hokkaido University, Kita, Sapporo 060-0819, Japan 4 Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan 5 Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, Chiba, 275-0016, Japan E-mail contact: akimasa.kataoka at nao.ac.jp Context: In planetesimal formation theory, several barriers have been proposed, which are bouncing, fragmentation, and radial drift problems. To understand the structure evolution of dust aggregates is a key in the planetesimal formation. Dust grains become fluffy by coagulation in protoplanetary disks. However, once they become fluffy, they are not sufficiently compressed by collisional compression to form compact planetesimals. Aims: We aim to reveal the pathway of the dust structure evolution from dust grains to compact planetesimals.

22 Methods: Using the compressive strength formula, we analytically investigate how fluffy dust aggregates are compressed by static compression due to ram pressure of the disk gas and self gravity of the aggregates in protoplanetary disks. Results: We reveal the pathway of the porosity evolution from dust grains via fluffy aggregates to form planetesimals, circumventing the barriers in planetesimal formation. The aggregates are compressed by the disk gas to the density of 10−3 g cm−3 in coagulation, which is more compact than the case with collisional compression. Then, they are compressed more by self gravity to 10−1 g cm−3 when the radius is 10 km. Although the gas compression decelerate the growth, they grow enough rapidly to avoid the radial drift barrier when the orbital radius is < 6 AU in a typical disk. Conclusions: We propose fluffy dust growth scenario from grains to planetesimals. It enables the icy planetesimal formation in a wide range beyond the snowline in protoplanetary disks. This result proposes a concrete initial condition of planetesimals for the later stages of the planet formation. Accepted by A&A letters http://arxiv.org/pdf/1307.7984

Observational evidence for dissociative shocks in the inner 100 AU of low-mass proto- stars using Herschel-HIFI L.E. Kristensen1,2, E.F. van Dishoeck1,3, A.O. Benz4, S. Bruderer3, R. Visser5, and S.F. Wamper6,7 1 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, the Netherlands 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 3 Max Planck Institut f¨ur Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany 4 Institute for Astronomy, ETH Zurich, 8093 Zurich, Switzerland 5 Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042, USA 6 Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark 7 Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark E-mail contact: lkristensen at cfa.harvard.edu

Herschel-HIFI spectra of H2O towards low-mass protostars show a distinct velocity component not seen in observations from the ground of CO or other species. The aim is to characterise this component in terms of excitation conditions −1 and physical origin. A velocity component with an offset of ∼10 km s detected in spectra of the H2O 110–101 557 GHz transition towards six low-mass protostars in the ’Water in star-forming regions with Herschel’ (WISH) programme is also seen in higher-excited H2O lines. The emission from this component is quantified and excitation conditions are inferred using 1D slab models. Data are compared to observations of hydrides (high-J CO, OH+, CH+, + C , OH) where the same component is uniquely detected. The velocity component is detected in all 6 targeted H2O transitions (Eup ∼ 50–250 K), and in CO 16–15 towards one source, Ser SMM1. Inferred excitation conditions imply 6 8 − that the emission arises in dense (n ∼ 5 × 10 –10 cm 3) and hot (T ∼ 750 K) gas. The H2O and CO column 16 18 −2 −2 densities are ∼10 and 10 cm , respectively, implying a low H2O abundance of 10 with respect to CO. The high column densities of ions such as OH+ and CH+ (both ∼1013 cm−2) indicate an origin close to the protostar where the UV field is strong enough that these species are abundant. The estimated radius of the emitting region is 100AU. This component likely arises in dissociative shocks close to the protostar, an interpretation corroborated by a comparison with models of such shocks. Furthermore, one of the sources, IRAS4A, shows temporal variability in the offset component over a period of two years which is expected from shocks in dense media. High-J CO gas detected with Herschel-PACS with Trot ∼ 700 K is identified as arising in the same component and traces the part of the shock where H2 reforms. Thus, H2O reveals new dynamical components, even on small spatial scales in low-mass protostars. Accepted by A&A http://arxiv.org/pdf/1307.1710

Configurations of Bounded and Free-floating Planets in Very Young Open Clusters Hui-Gen Liu, Hui Zhang, and Ji-Lin Zhou School of Astronomy and Space Science & Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University, Nanjing 2100093, China E-mail contact: huigen at nju.edu.cn

23 Open clusters (OCs) are usually young and suitable for studying the formation and evolution of planetary systems. Hitherto, only four planets have been found with radial velocity measurements in OCs. Meanwhile, a lot of free-floating planets (FFPs) have been detected. We utilize N-body simulations to investigate the evolution and final configurations of multi-planetary systems in very young open clusters with an age <10 Myr. After an evolution of 10 Myr, 61%– 72% of the planets remain bounded and more than 55% of the planetary systems will maintain their initial orbital configurations. For systems with one planet ejected, more than 25% of them have the surviving planets in misaligned orbits. In the clusters, the fraction of planetary systems with misalignment is > 6%, and only 1% have planets in retrograde orbits. We also obtain a positive correlation between the survival planet number and the distance from the cluster center r: planetary systems with a larger r tend to be more stable. Moreover, stars with a mass >2.5 M⊙ are likely unstable and lose their planets. These results are roughly consistent with current observations. Planetary 2 systems in binaries are less stable and we achieve a rough criterion: most of the binary systems with ab(1 − eb) >100 AU can keep all the initial planets survived. Finally, 80% of the FFPs are ejected out of the clusters, while the rest (∼20%) still stay in host clusters and most of them are concentrated in the center (<2 pc). Accepted by ApJ http://arxiv.org/pdf/1307.3908

Proper motions of young stars in Chamaeleon. II. New kinematical candidate members of Chamaeleon I and II Bel´en L´opez Mart´ı1, Francisco Jim´enez-Esteban1,2,3, Amelia Bayo4,5, David Barrado1,6, Enrique Solano1,2, Herv´eBouy1 and Carlos Rodrigo1,2 1 Centro de Astrobiolog´ıa(INTA-CSIC), Villanueva de la Ca˜nada, Spain 2 Spanish Virtual Observatory, Spain 3 Suffolk University, Madrid Campus, Madrid, Spain 4 European Southern Observatory, Santiago, Chile 5 Max-Planck-Institut f¨ur Astronomie, Heidelberg, Germany 6 Calar Alto Observatory -Centro Astron´omico Hispano-Alem´an, Almer´ıa, Spain E-mail contact: belen at cab.inta-csic.es Context: The Chamaeleon star-forming region has been extensively studied in the last decades. However, most studies have been confined to the densest parts of the clouds. In a previous paper, we analysed the kinematical properties of the spectroscopically confirmed population of the Chamaeleon I and II clouds. Aims: We want to search for new kinematical candidate members to the Chamaeleon I and II moving groups, extending the studied area beyond the clouds, and to characterize these new populations using available information from public databases and catalogues. We also want to check if the populations of the moving groups are confined to the present dark clouds. Methods: Kinematic candidate members were initially selected on the basis of proper motions and colours using the Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4). The SEDs of the objects were constructed using photometry retrieved from the Virtual Observatory and other resources, and fitted to models of stellar photospheres to derive effective temperatures, gravity values, and luminosities. Masses and ages were estimated by comparison < with theoretical evolutionary tracks in a Hertzprung-Russell diagram. Objects with ages ∼20 Myr were selected as probable members of the moving groups. Results: We have identified 51 and 14 candidate members to the Chamaeleon I and II moving groups, respectively, of which 17 and 1, respectively, are classified as probable young stars according to the SED analysis. Another object in Chamaeleon I located slightly above the 1 Myr isochrone is classified as a possible young star. All these objects are diskless stars with masses in the range 0.3-1.4M⊙ and ages consistent with those reported for the corresponding confirmed members. They tend to be located at the boundaries of or outside the dark clouds, preferably to the north-east and south-east in the case of Chamaeleon I, and to the north-east in the case of Chamaeleon II. Conclusions: The kinematical population of Chamaeleon I and II could be larger and spread over a larger area of the sky than suggested by previous studies. However, the results of this study should be confirmed with spectroscopic data and more precise kinematic information. Accepted by Astronomy and Astrophysics http://arxiv.org/pdf/1307.3414

24 Accurate determination of accretion and photospheric parameters in Young Stellar Ob- jects: the case of two candidate old disks in the Orion Nebula Cluster C.F. Manara1, G. Beccari1, N. Da Rio2, G. De Marchi2, A. Natta3,4, L. Ricci5, M. Robberto6 and L. Testi1,3,7 1 European Southern Observatory, Karl Schwarzschild Str. 2, 85748 Garching, Germany 2 European Space Agency, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands 3 INAF - Osservatorio Astrofisico di Arcetri, Largo E.Fermi 5, I-50125 Firenze, Italy 4 School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland 5 California Institute of Technology, 1200 East California Boulervard, 91125 Pasadena, CA, USA 6 Space Telescope Science Institute, 3700 San Martin Dr., Baltimore MD, 21218, USA 7 Excellence Cluster Universe, Boltzmannstr. 2, 85748 Garching, Germany E-mail contact: cmanara at eso.org Context. Current planet formation models are largely based on the observational constraint that protoplanetary disks have lifetime ∼3 Myr. Recent studies, however, report the existence of pre-Main-Sequence stars with signatures of accretion (strictly connected with the presence of circumstellar disks) and photometrically determined ages of 30 Myr, or more. Aims. Here we present a spectroscopic study of two major age outliers in the Orion Nebula Cluster. We use broad band, intermediate resolution VLT/X-Shooter spectra combined with an accurate method to determine the stellar parameters and the related age of the targets to confirm their peculiar age estimates and the presence of ongoing accretion. Methods. The analysis is based on a multi-component fitting technique, which derives simultaneously spectral type, extinction, and accretion properties of the objects. With this method we confirm and quantify the ongoing accretion. From the photospheric parameters of the stars we derive their position on the H-R Diagram, and the age given by evolutionary models. Together with other age indicators like the lithium equivalent width we estimate with high accuracy the age of the objects. Results. Our study shows that the two objects analyzed are not older than the typical population of the Orion Nebula Cluster. Our results show that, while photometric determination of the photospheric parameters are an accurate method to estimate the parameters of the bulk of young stellar populations, those of individual objects with high ac- cretion rates and extinction may be affected by large uncertainties. Broad band spectroscopic determinations should thus be used to confirm the nature of individual objects. Conclusions. The analysis carried out in this paper shows that this method allows us to obtain an accurate determina- tion of the photospheric parameters of accreting young stellar objects in any nearby star-forming region. We suggest that our detailed, broad- band spectroscopy method should be used to derive accurate properties of candidate old and accreting young stellar objects in star forming regions. We also discuss how a similarly accurate determination of stellar properties can be obtained through a combination of photometric and spectroscopic data. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1307.8118

Interferometric observations of nitrogen-bearing molecular species in the star-forming core ahead of HH 80N Josep M. Masqu´e1,2, Josep M. Girart3, Guillem Anglada2, Mayra Osorio2, Robert Estalella1 and Maria T. Beltr´an4 1 Departament d’Astronomia i Meteorologia, Universitat de Barcelona, Mart´ıi Franqu`es 1, 08028 Barcelona, Catalunya, Spain 2 Instituto de Astrof´ısica de Andaluc´ıa, CSIC, Camino Bajo de Hu´etor 50, E-18008 Granada, Spain 3 Institut de Ci`encies de l’Espai, (CSIC-IEEC), Campus UAB, Facultat de Ci`encies, Torre C5 - parell 2, 08193 Bel- laterra, Catalunya, Spain 4 INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy E-mail contact: j.masque at crya.unam.mx 13 We present VLA NH3 and PdBI NH2D and HN C observations of the star forming core ahead of HH 80N, the optically

25 obscured northern counterpart of the Herbig-Haro objects HH 80/81. The main goal is to determine the kinematical > 5 −3 information of the high density regions of the core (n ∼ 10 cm ), missed in previous works due to the depletion of the species observed (e.g. CS). The obtained maps show different kinematical signatures between the eastern and western parts of the core, suggesting a possible dynamical interaction of the core with the HH 80/81/80N outflow. The analysis of the Position-Velocity (PV) plots of these species rules out a previous interpretation of having a molecular ring-like structure of 6 × 104 AU of radius traced by CS infalling onto a central protostar found in the core (IRS1). High degree of NH3 deuteration, with respect to the central part of the core harboring IRS1, is derived in the eastern part, where a dust condensation (SE) is located. This deuteration trend of NH3 suggests that SE is in a prestellar evolutionary stage, earlier than that of the IRS1. Since SE is the closest condensation to the HH 80N/81/80N outflow, in case of having outflow-core dynamical interaction, it should be perturbed first and be the most evolved condensation in the core. Therefore, the derived evolutionary sequence for SE and IRS1 makes the outflow triggered star formation on IRS1 unlikely. Accepted by ApJ http://arxiv.org/pdf/1307.0761

ALMA imaging of the CO snowline of the HD 163296 disk with DCO+ G.S. Mathews1, P.D. Klaassen1, A. Juh´asz1, D. Harsono1,2, E. Chapillon3, E.F. van Dishoeck1,4, D. Espada5,6, I. de Gregorio-Monsalvo5,7, A. Hales8, M.R. Hogerheijde1, J.C. Mottram1, M.G. Rawlings9, S. Takahashi3, and L. Testi7,10 1 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 2 SRON Netherlands Institute for Space Research, PO Box 9700 AV, Groningen, The Netherlands 3 Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), P.O. Box 23-141, Taipei 10617, Taiwan 4 Max-Planck-Institut f¨ur Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany 5 National Astronomical Observatory of Japan (NAOJ), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 6 NAOJ Chile Observatory 7 European Southern Observatory, Karl Schwarzschild Str 2, D-85748 Garching bei M¨unchen, Germany 8 Joint ALMA Observatory (JAO), Alonso de Cordova 3107, Vitacura, Santiago, Chile 9 National Radio Astronomical Observatory (NRAO), 520 Edgemont Road, Charlottesville, VA 22903, USA 10 INAF - Osservatorio Astrosico di Arcetri, Largo E. Fermi 5, 50125,Firenze, Italy E-mail contact: gmathews at strw.leidenuniv.nl The high spatial and line sensitivity of ALMA opens the possibility of resolving emission from molecules in circumstellar disks. With an understanding of physical conditions under which molecules have high abundance, they can be used as direct tracers of distinct physical regions. In particular, DCO+ is expected to have an enhanced abundance within a few Kelvin of the CO freezeout temperature of 19 K, making it a useful probe of the cold disk midplane. We compare ALMA line observations of HD 163296 to a grid of models. We vary the upper- and lower-limit temperatures of the region in which DCO+ is present as well as the abundance of DCO+ in order to fit channel maps of the DCO+ J=5–4 line. To determine the abundance enhancement compared to the general interstellar medium, we carry out similar fitting to HCO+ J=4–3 and H13CO+ J=4–3 observations. ALMA images show centrally peaked extended emission from HCO+ and H13CO+. DCO+ emission lies in a resolved ring from ∼110 to 160 AU. The outer radius approximately corresponds to the size of the CO snowline as measured by previous lower resolution observations of CO lines in this disk. The ALMA DCO+ data now resolve and image the CO snowline directly. In the best fitting models, HCO+ exists in a region extending from the 19 K isotherm to the photodissociation layer with an abundance −10 + + of 3 × 10 relative to H2. DCO exists within the 19–21 K region of the disk with an abundance ratio [DCO ]/ [HCO+] = 0.3. This represents a factor of 104 enhancement of the DCO+ abundance within this narrow region of the HD 163296 disk. Such a high enhancement has only previously been seen in prestellar cores. The inferred abundances provide a lower limit to the ionization fraction in the midplane of the cold outer disk (approximately greater than −10 + + 4 × 10 ), and suggest the utility of DCO as a tracer of its parent molecule H2D . Abridged Accepted by A&A http://arxiv.org/pdf/1307.3420

26 YSO accretion shocks: magnetic, chromospheric or stochastic flow effects can suppress fluctuations of X-ray emission T. Matsakos1,2,3, J.-P. Chi´eze2, C. Stehl´e3, M. Gonz´alez4, L. Ibgui3, L. de S´a2,3, T. Lanz5, S. Orlando6, R. Bonito7,6, C. Argiroff7,6, F. Reale7,6and G. Peres7,6 1 CEA, IRAMIS, Service Photons, Atomes et Mol´ecules, 91191 Gif-sur-Yvette, France 2 Laboratoire AIM, CEA/DSM - CNRS - Universit´eParis Diderot, IRFU/Service dAstrophysique,´ CEA Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France 3 LERMA, Observatoire de Paris, Universit´ePierre et Marie Curie and CNRS, 5 Place J. Janssen, 92195 Meudon, France 4 Universit´eParis Diderot, Sorbonne Paris Cit´e, AIM, UMR 7158, CEA, CNRS, 91191 Gif-sur-Yvette, France 5 Laboratoire Lagrange, Universit´ede Nice-Sophia Antipolis, CNRS, Observatoire de la Cˆote d’Azur, 06304 Nice cedex 4, France 6 INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy 7 Dipartimento di Fisica e Chimica, Universit´adegli Studi di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy E-mail contact: titos.matsakos at gmail.com Context. Theoretical arguments and numerical simulations of radiative shocks produced by the impact of the accreting gas onto young stars predict quasi-periodic oscillations in the emitted radiation. However, observational data do not show evidence of such periodicity. Aims. We investigate whether physically plausible perturbations in the accretion column or in the chromosphere could disrupt the shock structure influencing the observability of the oscillatory behavior. Methods. We performed local 2D magneto-hydrodynamical simulations of an accretion shock impacting a chromo- sphere, taking optically thin radiation losses and thermal conduction into account. We investigated the effects of several perturbation types, such as clumps in the accretion stream or chromospheric fluctuations, and also explored a wide range of plasma-β values. Results. In the case of a weak magnetic field, the post-shock region shows chaotic motion and mixing, smoothing out the perturbations and retaining a global periodic signature. On the other hand, a strong magnetic field confines the plasma in flux tubes, which leads to the formation of fibrils that oscillate independently. Realistic values for the amplitude, length, and time scales of the perturbation are capable of bringing the fibril oscillations out of phase, suppressing the periodicity of the emission. Conclusions. The strength of a locally uniform magnetic field in YSO accretion shocks determines the structure of the post-shock region, namely, whether it will be somewhat homogeneous or if it will split up to form a collection of fibrils. In the second case, the size and shape of the fibrils is found to depend strongly on the plasma-β value but not on the perturbation type. Therefore, the actual value of the protostellar magnetic field is expected to play a critical role in the time dependence of the observable emission. Accepted by A&A http://arxiv.org/pdf/1307.5389

ALMA observations of the massive molecular outflow G331.512-0.103 Manuel Merello1,2, Leonardo Bronfman1, Guido Garay1, Nadia Lo1, Neal J. Evans II2, Lars-Ake Nyman3, Juan R. Corts3 and Maria R. Cunningham4 1 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 2 The University of Texas at Austin, Department of Astronomy, 2515 Speedway, Stop C1400, Austin, Texas 78712-1205 3 Joint ALMA Observatory (JAO), Alonso de Cordova 3107, Vitacura, Santiago, Chile 4 School of Physics, University of New South Wales, Sydney, NSW 2052, Australia E-mail contact: manuel at astro.as.utexas.edu The object of this study is one of the most energetic and luminous molecular outflows known in the Galaxy, G331.512- 0.103. Observations with ALMA Band 7 (350 GHz; 0.86 mm) reveal a very compact, extremely young bipolar outflow and a more symmetric outflowing shocked shell surrounding a very small region of ionized gas. The velocities of the bipolar outflow are about 70 km s−1 on either side of the systemic velocity. The expansion velocity of the shocked shell is ∼24 km s−1, implying a crossing time of about 2000 yrs. Along the symmetry axis of the outflow, there is a

27 velocity feature, which could be a molecular ”bullet” of high-velocity dense material. The source is one of the youngest examples of massive molecular outflow found associated with a high-mass star. Accepted by ApJ Letters http://arxiv.org/pdf/1307.6244

Growth of grains in Brown Dwarf disks Farzana Meru1, Marina Galvagni2 and Christoph Olczak3,4,5 1 Institut f¨ur Astronomie, ETH Z¨urich, Wolfgang-Pauli-Strasse 27, 8093 Z¨urich, Switzerland 2 Institute of Theoretical Physics, Universit¨at Z¨urich, Winterthurerstrasse 190, 8057 Z¨urich, Switzerland 3 Astronomisches Rechen-Institut (ARI), Zentrum f¨ur Astronomie Universit¨at Heidelberg, M¨onchhofstrasse 12-14, 69120 Heidelberg, Germany 4 Max-Planck-Institut f¨ur Astronomie (MPIA), K¨onigstuhl 17, 69117 Heidelberg, Germany 5 National Astronomical Observatories of China, Chinese Academy of Sciences (NAOC/CAS), 20A Datun Lu, Chaoyang District, Beijing 100012, China E-mail contact: farzana.meru at phys.ethz.ch We perform coagulation and fragmentation simulations using the new physically-motivated model by Garaud et al. 2013 to determine growth locally in brown dwarf disks. We show that large grains can grow and that if brown dwarf disks are scaled down versions of T Tauri disks (in terms of stellar mass, disk mass and disk radius) growth at an equivalent location with respect to the disk truncation radius can occur to the same size in both disks. We show that similar growth occurs because the collisional timescales in the two disks are comparable. Our model may therefore potentially explain the recent observations of grain growth to millimetre sizes in brown dwarf disks, as seen in T Tauri disks. Accepted by ApJ Letters http://arxiv.org/pdf/1307.3708

New and updated stellar parameters for 71 evolved planet hosts. On the metallicity - giant planet connection A. Mortier1,2, N.C. Santos1,2, S.G. Sousa1,3, V.Zh. Adibekyan1, E. Delgado Mena1, M.Tsantaki1,2, G. Israelian3,4 and M. Mayor5 1 Centro de Astrof´ısica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal 2 Departamento de F´ısica e Astronomia, Faculdade de Ciˆencias, Universidade do Porto, Portugal 3 Instituto de Astrof´ısica de Canarias, 38200 La Laguna, Tenerife, Spain 4 Departemento de Astrof´ısica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain 5 Observatoire de Gen`eve, Universit´ede Gen`eve, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland E-mail contact: amortier at astro.up.pt Context. It is still being debated whether the well-known metallicity - giant planet correlation for dwarf stars is also valid for giant stars. For this reason, having precise metallicities is very important. Precise stellar parameters are also crucial to planetary research for several other reasons. Different methods can provide different results that lead to discrepancies in the analysis of planet hosts. Aims. To study the impact of different analyses on the metallicity scale for evolved stars, we compare different iron line lists to use in the atmospheric parameter derivation of evolved stars. Therefore, we use a sample of 71 evolved stars with planets. With these new homogeneous parameters, we revisit the metallicity - giant planet connection for evolved stars. Methods. A spectroscopic analysis based on Kurucz models in local thermodynamic equilibrium (LTE) was performed through the MOOG code to derive the atmospheric parameters. Two different iron line list sets were used, one built for cool FGK stars in general, and the other for giant FGK stars. Masses were calculated through isochrone fitting, using the Padova models. Kolmogorov-Smirnov tests (K-S tests) were then performed on the metallicity distributions of various different samples of evolved stars and red giants.

28 Results. All parameters compare well using a line list set, designed specifically for cool and solar-like stars to provide more accurate temperatures. All parameters derived with this line list set are preferred and are thus adopted for future analysis. We find that evolved planet hosts are more metal-poor than dwarf stars with giant planets. However, a bias in giant stellar samples that are searched for planets is present. Because of a colour cut-off, metal-rich low-gravity stars are left out of the samples, making it hard to compare dwarf stars with giant stars. Furthermore, no metallicity enhancement is found for red giants with planets (log g < 3.0 dex) with respect to red giants without planets. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1307.7870

Stars on the run: escaping from stellar clusters Guido R.I. Moyano Loyola1 and Jarrod R. Hurley1 1 Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218, Australia E-mail contact: gmoyano at astro.swin.edu.au A significant proportion of Milky Way stars are born in stellar clusters, which dissolve over time so that the members become part of the disc and halo populations of the Galaxy. In the present work we will assume that these young stellar clusters live mainly within the disc of the Galaxy and that they can have primordial binary percentages ranging from 0% to as high as 70%. We have evolved models of such clusters to an age of 4 Gyr through N-body simulations, paying attention to the stars and binaries that escape in the process. We have quantified the contribution of these escaping stars to the Galaxy population by analysing their escape velocity and evolutionary stage at the moment of escape. In this way we could analyse the mechanisms that produced these escapers, whether evaporation through weak two- body encounters, energetic close encounters or stellar evolution events, e.g. supernovae. In our models we found that the percentage of primordial binaries in a star cluster does not produce significant variations in the velocities of the stars that escape in the velocity range of 0–20 km s−1. However, in the high-velocity 20–100 km s−1 range the number of escapers increased markedly as the primordial binary percentage increased. We could also infer that dissolving stellar clusters such as those that we have modelled can populate the Galactic halo with giant stars for which the progenitors were stars of up to 2.4 M⊙. Furthermore, choices made for the velocity kicks of remnants do influence the production of hyper-velocity stars - and to a lesser extent stars in the high-velocity range - but once again the difference for the 99% of stars in the 0–20 km s−1 range is not significant. Accepted by MNRAS http://arxiv.org/pdf/1307.1468

A survey of H2O, CO2 and CO ice features towards background stars and low mass YSOs using AKARI. Jennifer A. Noble1, Helen J. Fraser2, Yuri Aikawa3, Klaus M. Pontoppidan4 and Itsuki Sakon5 1 Aix-Marseille Universit´e, PIIM UMR 7345, 13397, Marseille, France. 2 Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, United Kingdom. 3 Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501, Japan. 4 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, U.S.A. 5 Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113- 0003, Japan. E-mail contact: helen.fraser at open.ac.uk We present near infrared spectroscopic observations of 19 molecular clouds made using the AKARI satellite, and the data reduction pipeline written to analyse those observations. The 2.5 – 5 µm spectra of 30 objects – 22 field stars behind quiescent molecular clouds and eight low mass YSOs in cores – were successfully extracted using the pipeline. Those spectra are further analysed to calculate the column densities of key solid phase molecular species, including − H2O, CO2, CO, and OCN . The profile of the H2O ice band is seen to vary across the objects observed and we suggest that the extended red wing may be an evolutionary indicator of both dust and ice mantle properties. The observation of 22 spectra with fluxes as low as < 5 mJy towards background stars, including 15 where the column densities of H2O, CO and CO2 were calculated, provides valuable data that could help to benchmark the initial conditions in

29 star-forming regions prior to the onset of star formation. Accepted by ApJ http://arxiv.org/pdf/1307.1527

Testing protoplanetary disc dispersal with radio emission James E. Owen1, Anna M.M. Scaife2and Barbara Ercolano3,4 1 Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, M5S 3H8, Canada 2 School of Physics & Astronomy, University of Southampton, Higheld, Southampton SO17 1BJ, England 3 Excellence Cluster Universe, Boltzmannstr. 2, D-85748 Garching, Germany 4 Universit¨ats-Sternwarte M¨unchen, Scheinerstrasse 1, D-81679 M¨unchen, Germany E-mail contact: jowen at cita.utoronto.ca We consider continuum free-free radio emission from the upper atmosphere of protoplanetary discs as a probe of the ionized luminosity impinging upon the disc. Making use of previously computed hydrodynamic models of disc photoevaporation within the framework of EUV and X-ray irradiation, we use radiative transfer post-processing techniques to predict the expected free-free emission from protoplanetary discs. In general, the free-free luminosity scales roughly linearly with ionizing luminosity in both EUV and X-ray driven scenarios, where the emission dominates over the dust tail of the disc and is partial optically thin at cm wavelengths. We perform a test observation of GM Aur at 14-18 GHz and detect an excess of radio emission above the dust tail to a very high level of confidence. The observed flux density and spectral index are consistent with free-free emission from the ionized disc in either the EUV or X-ray driven scenario. Finally, we suggest a possible route to testing the EUV and X-ray driven dispersal model of protoplanetary discs, by combining observed free-free flux densities with measurements of mass-accretion rates. On 2 the point of disc dispersal one would expect to find a M˙ ∗ scaling with free-free flux in the case of EUV driven disc dispersal or a M˙ ∗ scaling in the case of X-ray driven disc dispersal. Accepted by MNRAS http://arxiv.org/pdf/1307.2240

The formation of systems with closely spaced low-mass planets and the application to Kepler-36 S. Paardekooper1, H. Rein2,3 and W. Kley4 1 DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom 2 Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ 08540, USA 3 University of Toronto, Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada 4 Institut fuer Astronomie und Astrophysik, Universitaet Tuebingen, Auf der Morgenstelle 10, 72076 Tuebingen, Germany E-mail contact: S.Paardekooper at damtp.cam.ac.uk The Kepler-36 system consists of two planets that are spaced unusually close together, near the 7:6 mean motion resonance. While it is known that mean motion resonances can easily form by convergent migration, Kepler-36 is an extreme case due to the close spacing and the relatively high planet masses of 4 and 8 times that of the Earth. In this paper, we investigate whether such a system can be obtained by interactions with the protoplanetary disc. These discs are thought to be turbulent and exhibit density fluctuations which might originate from the magneto-rotational instability. We adopt a realistic description for stochastic forces due to these density fluctuations and perform both long term hydrodynamical and N-body simulations. Our results show that planets in the Kepler-36 mass range can be naturally assembled into a closely spaced planetary system for a wide range of migration parameters in a turbulent disc similar to the minimum mass solar nebula. The final orbits of our formation scenarios tend to be Lagrange stable, even though large parts of the parameter space are chaotic and unstable. Accepted by MNRAS http://arxiv.org/pdf/1304.4762

30 Infrared Emission and the Destruction of Dust in HII regions Ya.N. Pavlyuchenkov1 , M.S. Kirsanova1 and D.S. Wiebe1 1 Institute of Astronomy, Russian Academy of Sciences, Moscow, Russia E-mail contact: pavyar at inasan.ru The generation of infrared (IR) radiation and the observed IR intensity distribution at wavelengths of 8, 24, and 100 micron in the ionized hydrogen region around a young, massive star is investigated. The evolution of the HII region is treated using a self-consistent chemical-dynamical model in which three dust populations are included – large silicate grains, small graphite grains, and polycyclic, aromatic hydrocarbons (PAHs). A radiative transfer model taking into account stochastic heating of small grains and macromolecules is used to model the IR spectral energy distribution. The computational results are compared with Spitzer and Herschel observations of the RCW 120 nebula. The contributions of collisions with gas particles and the radiation field of the star to stochastic heating of small grains are investigated. It is shown that a model with a homogeneous PAH content cannot reproduce the ring-like IR-intensity distribution at 8 micron. A model in which PAHs are destroyed in the ionized region provides a means to explain this intensity distribution. This model is in agreement with observations for realistic characteristic destruction times for the PAHs. Accepted by Astronomy Reports http://arxiv.org/pdf/1307.6504

Intrinsic Colors, Temperatures, and Bolometric Corrections of Pre-Main Sequence Stars Mark J. Pecaut1 and Eric E. Mamajek1 1 University of Rochester, Department of Physics and Astronomy, Rochester, NY 14627-0171, USA E-mail contact: mpecaut at pas.rochester.edu We present an analysis of the intrinsic colors and temperatures of 5–30 Myr old pre-main sequence (pre-MS) stars using the F0 through M9 type members of nearby, negligibly reddened groups: Eta Cha cluster, TW Hydra Association, Beta Pic Moving Group, and Tucana-Horologium Association. To check the consistency of spectral types from the literature, we estimate new spectral types for 52 nearby pre-MS stars with spectral types F3 through M4 using optical spectra taken with the SMARTS 1.5-m telescope. Combining these new types with published spectral types, and photometry from the literature (Johnson-Cousins BVIc, 2MASS JHKs and WISE W1, W2, W3, and W4), we derive a new empirical spectral type-color sequence for 5–30 Myr old pre-MS stars. Colors for pre-MS stars match dwarf colors for some spectral types and colors, but for other spectral types and colors, deviations can exceed 0.3 mag. We estimate effective temperatures (Teff ) and bolometric corrections (BCs) for our pre-MS star sample through comparing their photometry to synthetic photometry generated using the BT-Settl grid of model atmosphere spectra. We derive a new Teff and BC scale for pre-MS stars, which should be a more appropriate match for T Tauri stars than often-adopted dwarf star scales. While our new Teff scale for pre-MS stars is within ∼100 K of dwarfs at a given spectral type for stars

Global collapse of molecular clouds as a formation mechanism for the most massive stars N. Peretto1,2, G.A. Fuller3,4, A. Duarte-Cabral5,6 , A. Avison3,4, P. Hennebelle1, J.E. Pineda3,4,7, Ph. Andr´e1, S. Bontemps5,6 , F. Motte1, N. Schneider5,6, S. Molinari8 1 Laboratoire AIM, CEA/DSM-CNRS-Universt´eParis Diderot, IRFU/Service d’Astrophysique, C.E. Saclay, France 2 School of Physics and Astronomy, Cardi University, Queens Buildings, The Parade, Cardi CF24 3AA, UK 3 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, M13

31 9PL, UK 4 UK ALMA Regional Centre node 5 Universit´et de Bordeaux, LAB, UMR5804, F-33270, Floirac, France 6 CNRS, LAB, UMR5804, F-33270, Floirac, France 7 European Southern Observatory (ESO), Garching, Germany 8 IFSI, INAF, Area di Recerca di Tor Vergata, Via Fosso Cavaliere 100, I-00133, Roma, Italy E-mail contact: nicolas.peretto at astro.cf.ac.uk The relative importance of primordial molecular cloud fragmentation versus large-scale accretion still remains to be assessed in the context of massive core/star formation. Studying the kinematics of the dense gas surrounding massive- star progenitors can tell us the extent to which large-scale flow of material impacts the growth in mass of star-forming cores. Here we present a comprehensive dataset of the 5500(±800) M⊙ infrared dark cloud SDC335.579-0.272 (hereafter SDC335) which exhibits a network of cold, dense, parsec-long filaments. Atacama Large Millimeter Array (ALMA) Cycle 0 observations reveal two massive star-forming cores, MM1 and MM2, sitting at the centre of SDC335 where the +770 filaments intersect. With a gas mass of 545(−385) M⊙ contained within a source diameter of 0.05 pc, MM1 is one of the most massive, compact protostellar cores ever observed in the Galaxy. As a whole, SDC335 could potentially form an OB cluster similar to the Trapezium cluster in Orion. ALMA and Mopra single-dish observations of the SDC335 dense gas furthermore reveal that the kinematics of this hub-filament system are consistent with a global collapse −1 of the cloud. These molecular-line data point towards an infall velocity Vinf = 0.7(±0.2) km s , and a total mass −3 −1 infall rate M˙ inf = 2.5(±1.0) × 10 M⊙ yr towards the central pc-size region of SDC335. This infall rate brings 5 750(±300) M⊙ of gas to the centre of the cloud per free-fall time (tff = 3 × 10 yr). This is enough to double the +2.2 mass already present in the central pc-size region in 3.5(−1.0) × tff . These values suggest that the global collapse of SDC335 over the past million year resulted in the formation of an early O-type star progenitor at the centre of the cloud’s gravitational potential well. Accepted by A&A http://arxiv.org/pdf/1307.2590

CARMA observations of protostellar outflows in NGC 1333 Adele L. Plunkett1, Hector G. Arce1, Stuartt A. Corder2, Diego Mardones3, Anneila I. Sargent4 and Scott L. Schnee5 1 Department of Astronomy, Yale University, P.O. Box 208101, New Haven CT 06520, USA 2 Joint ALMA Observatory, Av. Alonso de Cordova 3107, Vitacura, Santiago, Chile 3 Departameto de Astronomia, Universidad de Chile, Casilla 36-D, Santiago, Chile 4 Astronomy Department, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA 5 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA E-mail contact: adele.plunkett at yale.edu We present observations of outflows in the star-forming region NGC 1333 using the Combined Array for Research in Millimeter-Wave Astronomy (CARMA). We combined the 12CO and 13CO (1 − 0) CARMA mosaics with data from the 14m Five College Radio Astronomy Observatory to probe the central, most dense and active region of this protostellar cluster at scales from 5′′ to 7′ (or 1000 AU to 0.5 pc at a distance of 235 pc). We map and identify 12CO outflows, and along with 13CO data we estimate their mass, momentum, and energy. Within the 7′ × 7′ map, the 5′′ resolution allows for a detailed study of morphology and kinematics of outflows and outflow candidates, some of which were previously confused with other outflow emission in the region. In total, we identify 22 outflow lobes, as well as 9 dense circumstellar envelopes marked by continuum emission, of which 6 drive outflows. We calculate −1 44 a total outflow mass, momentum, and energy within the mapped region of 6 M⊙, 19 M⊙ km s , and 7 ×10 erg, respectively. Within this same region, we compare outflow kinematics with turbulence and gravitational energy, and we suggest that outflows are likely important agents for the maintenance of turbulence in this region. In the earliest stages of star formation, outflows do not yet contribute enough energy to totally disrupt the clustered region where most star formation is happening, but have the potential to do so as the protostellar sources evolve. Our results can be used to constrain outflow properties, such as outflow strength, in numerical simulations of outflow-driven turbulence in clusters.

32 Accepted by Astrophysical Journal http://arxiv.org/pdf/1307.3558

An O2If* star found in isolation in the backyard of NGC 3603 A. Roman-Lopes1 1 Department of Physics - Universidad de La Serena - Cisternas, 1200 - La Serena - Chile E-mail contact: roman at dfuls.cl In this letter we communicate the identification of a new Galactic O2If* star (MTT 68) isolated at a projected linear distance of 3 pc from the centre of the star-burst cluster NGC 3603. From its optical photometry I computed a 6 bolometric luminosity MBol = −10.7, which corresponds to a total stellar luminosity of 1.5 × 10 L⊙. It was found an interesting similarity between MTT 68 and the well known multiple system HD 93129. From Hubble Space Telescope F656N images of the NGC 3603 field, it was found that MTT 68 is actually a visual binary system with an angular ′′ −2 separation of 0. 38, which corresponds to a projected (minimum) linear distance of rA−B = 1.4 × 10 pc. This value −2 is similar to that for the HD 93129A (O2If*) and HD 93129B (O3.5) pair, rA−B = 3.0 × 10 pc. On the other hand, HD93129A has a third closer companion named HD 93129Ab (O3.5) at only 0′′. 053, and taking into account that the −5 X-ray to total stellar luminosity ratio for the MTT 68 system (LX /LBol ∼ 10 ) is about two orders of magnitude above the canonical value expected for single stars, I suspect that the MTT 68 system probably hosts another massive companion not resolved by the HST archive images. Accepted by MNRAS letters http://arxiv.org/pdf/1307.7061

Imaging of the CO Snow Line in a Solar Nebula Analog Chunhua Qi1, Karin I. Oberg1,2, David J. Wilner1, Paola D’Alessio3, Edwin Bergin4, Sean M. Andrews1, Geoffrey A. Blake5, Michiel R. Hogerheijde6 and Ewine F. van Dishoeck6,7 1 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA 2 Departments of Chemistry and Astronomy, University of Virginia, Charlottesville, VA 22904, USA 3 Centro de Radioastronomoa y Astrofisica, Universidad Nacional Autonoma de Mexico (UNAM), 58089 Mexico City, Mexico 4 Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA 5 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA 6 Leiden Observatory, Leiden University, 2300 RA, Leiden, Netherlands 7 Max Planck Institute for Extraterrestrial Physics, 85748, Garching, Germany E-mail contact: cqi at cfa.harvard.edu Planets form in the disks around young stars. Their formation efficiency and composition are intimately linked to the protoplanetary disk locations of “snow lines” of abundant volatiles. We present chemical imaging of the CO snow line in the disk around TW Hya, an analog of the solar nebula, using high spatial and spectral resolution Ata- + cama Large Millimeter/Submillimeter Array (ALMA) observations of N2H , a reactive ion present in large abundance + only where CO is frozen out. The N2H emission is distributed in a large ring, with an inner radius that matches CO snow line model predictions. The extracted CO snow line radius of ∼ 30 AU helps to assess models of the formation dynamics of the Solar System, when combined with measurements of the bulk composition of planets and comets. Accepted by Science http://arxiv.org/pdf/1307.7439

HH 222: A Giant Herbig-Haro Flow from the Quadruple System V380 Ori Bo Reipurth1, John Bally2, Colin Aspin1, M.S. Connelley1, T.R. Geballe3, Stefan Kraus4, Immo Appenzeller5, and Adam Burgasser6 1 Institute for Astronomy, University of Hawaii at Manoa, 640 North Aohoku Place, Hilo, HI 96720, USA 2 Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309, USA 3 Gemini Observatory, 670 North Aohoku Place, Hilo, HI 96720, USA

33 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138, USA 5 Landessternwarte Heidelberg, K¨onigstuhl 12, D-69117 Heidelberg, Germany 6 Center for Astrophysics and Space Science, University of California San Diego, La Jolla, CA 92093, USA E-mail contact: reipurth at ifa.hawaii.edu HH 222 is a giant shocked region in the L1641 cloud, and is popularly known as the Orion Streamers or ”the waterfall” on account of its unusual structure. At the center of these streamers are two infrared sources coincident with a nonthermal radio jet aligned along the principal streamer. The unique morphology of HH 222 has long been associated with this radio jet. However, new infrared images show that the two sources are distant elliptical galaxies, indicating that the radio jet is merely an improbable line-of-sight coincidence. Accurate proper motion measurements of HH 222 reveal that the shock structure is a giant bow shock moving directly away from the well-known, very young, Herbig Be star V380 Ori. The already known Herbig-Haro object HH 35 forms part of this flow. A new Herbig-Haro object, HH 1041, is found precisely in the opposite direction of HH 222 and is likely to form part of a counterflow. The total projected extent of this HH complex is 5.3 pc, making it among the largest HH flows known. A second outflow episode from V380 Ori is identified as a pair of HH objects, HH 1031 to the northwest and the already known HH 130 to the southeast, along an axis that deviates from that of HH 222/HH 1041 by only 3.7◦. V380 Ori is a hierarchical quadruple system, including a faint companion of spectral type M5 or M6, which at an age of ∼1 Myr corresponds to an object straddling the stellar-to-brown dwarf boundary. We suggest that the HH 222 giant bow shock is a direct result of the dynamical interactions that led to the conversion from an initial non-hierarchical multiple system into a hierarchical configuration. This event occurred no more than 28,000 yr ago, as derived from the proper motions of the HH 222 giant bow shock. Accepted by Astron. J. http://www.ifa.hawaii.edu/users/reipurth/PREPRINTS/hh222.pdf

Resolving The Moth at Millimeter Wavelengths Angelo Ricarte1, Noel Moldvai1, A. Meredith Hughes2, Gaspard Duchˆene1,3, Jonathan P. Williams4, Sean M. Andrews5 and David J. Wilner5 1 University of California Berkeley, Department of Astronomy, 601 Campbell Hall, Berkeley, CA 94720, USA 2 Wesleyan University Department of Astronomy, Van Vleck Observatory, 96 Foss Hill Drive, Middletown, CT 06459, USA 3 UJF-Grenoble 1/ CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, BP 53, 38041 Grenoble Cedex 9, France 4 Institute for Astronomy, University of Hawaii, USA 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA E-mail contact: angelo.ricarte at yale.edu HD 61005, also known as “The Moth,” is one of only a handful of debris disks that exhibit swept-back “wings” thought to be caused by interaction with the ambient interstellar medium (ISM). We present 1.3 mm Submillimeter Array (SMA) observations of the debris disk around HD 61005 at a spatial resolution of 1.9 arcsec that resolve the emission from large grains for the first time. The disk exhibits a double-peaked morphology at millimeter wavelengths, consistent with an optically thin ring viewed close to edge-on. To investigate the disk structure and the properties of the dust grains we simultaneously model the spatially resolved 1.3 mm visibilities and the unresolved spectral energy distribution. The temperatures indicated by the SED are consistent with expected temperatures for grains close to the blowout size located at radii commensurate with the millimeter and scattered light data. We also perform a visibility-domain analysis of the spatial distribution of millimeter-wavelength flux, incorporating constraints on the disk geometry from scattered light imaging, and find suggestive evidence of wavelength-dependent structure. The millimeter-wavelength emission apparently originates predominantly from the thin ring component rather than tracing the “wings” observed in scattered light. The implied segregation of large dust grains in the ring is consistent with an ISM-driven origin for the scattered light wings. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1307.3560

34 The GALEX Nearby Young-Star Survey David R. Rodriguez1, B. Zuckerman2, Joel H. Kastner3, M.S. Bessell4, Jacqueline K. Faherty1,5, Simon J. Murphy4,6 1 Departamento de Astronoma, Universidad de Chile, Casilla 36-D, Santiago, Chile 2 Dept. of Physics & Astronomy, University of California, Los Angeles 90095, USA 3 Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester NY 14623 4 The Australian National University, Cotter Road, Weston Creek ACT 2611, Australia 5 Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10034 6 Gliese Fellow, Astronomisches Rechen-Institut, Zentrum f¨ur Astronomie der Universit¨at Heidelberg, Germany 69120 E-mail contact: drodrigu at das.uchile.cl We describe a method that exploits data from the GALEX ultraviolet and WISE and 2MASS infrared source catalogs, combined with proper motions and empirical pre-main sequence isochrones, to identify candidate nearby, young, low- mass stars. Applying our method across the full GALEX- covered sky, we identify 2031 mostly M-type stars that, for an assumed age of 10 (100) Myr, all lie within ∼150 (∼90) pc of Earth. The distribution of M spectral subclasses among these ∼2000 candidate young stars peaks sharply in the range M3–M4; these subtypes constitute 50% of the sample, consistent with studies of the M star population in the immediate solar neighborhood. We focus on a subset of 58 of these candidate young M stars in the vicinity of the Tucana-Horologium Association. Only 20 of these 58 candidates were detected in the ROSAT All-Sky X-ray Survey – reflecting the greater sensitivity of GALEX for purposes of identifying active nearby, young stars, particularly for stars of type M4 and later. Based on statistical analysis of the kinematics and/or spectroscopic followup of these 58 M stars, we find that 50% (29 stars) indeed have properties consistent with Tuc-Hor membership, while 12 are potential new members of the Columba Association, and two may be AB Dor moving group members. Hence, ∼75% of our initial subsample of 58 candidates are likely members of young (age ∼10–40 Myr) stellar moving groups within 100 pc, verifying that the stellar color- and kinematics-based selection algorithms described here can be used to efficiently isolate nearby, young, low-mass objects from among the field star population. Future studies will focus on characterizing additional subsamples selected from among this list of candidate nearby, young M stars. Accepted by ApJ http://arxiv.org/pdf/1307.3262

Distinct Chemical Regions in the ”Prestellar” Infrared Dark Cloud (IRDC) G028.23- 00.19 Patricio Sanhueza1, James M. Jackson1, Jonathan B. Foster2, Izaskun Jimenez-Serra3, William J. Dirienzo4 and Thushara Pillai5 1 Institute for Astrophysical Research, Boston University, Boston, MA 02215, USA 2 Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06520, USA 3 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany 4 Department of Astronomy, University of Virginia, P.O. Box 3818, Charlottesville, VA 22903, USA 5 Caltech, MC 249-17, 1200 East California Blvd, Pasadena, CA 91125, USA E-mail contact: patricio at bu.edu We have observed the IRDC G028.23-00.19 at 3.3 mm using CARMA. In its center, the IRDC hosts one of the most massive (∼1520 M⊙) quiescent, cold (12 K) clumps known (MM1). The low temperature, high NH2D abundance, narrow molecular line widths, and absence of embedded IR sources (from 3.6 to 70 µm) indicate that the clump is likely prestellar. Strong SiO emission with broad line widths (6-9 km s−1) and high abundances (0.8-4 × 10−9) is detected in the northern and southern regions of the IRDC, unassociated with MM1. We suggest that SiO is released to the gas phase from the dust grains through shocks produced by outflows from undetected intermediate-mass stars or clusters of low-mass stars deeply embedded in the IRDC. A weaker SiO component with narrow line widths (∼2 kms−1) and low abundances (4.3 × 10−11) is detected in the center-west region, consistent with either a “subcloud-subcloud” collision or an unresolved population of a few low-mass stars. We report widespread CH3OH emission throughout the whole IRDC and the first detection of extended narrow methanol emission (∼2 km s−1) in a cold, massive prestellar

35 clump (MM1). We suggest that the most likely mechanism releasing methanol into the gas phase in such a cold region is the exothermicity of grain-surface reactions. HN13C reveals that the IRDC is actually composed of two distinct substructures (“subclouds”) separated in velocity space by ∼1.4 km s−1. The narrow SiO component arises where the subclouds overlap. The spatial distribution of C2H resembles that of NH2D, which suggests that C2H also traces cold gas in this IRDC. Accepted by ApJ http://arxiv.org/pdf/1307.1474

Herschel PACS observations of shocked gas associated with the jets of L1448 and L1157 G. Santangelo1, B. Nisini1, S. Antoniucci1, C. Codella2, S. Cabrit3, T. Giannini1, G. Herczeg4,R. Liseau5, M. Tafalla6 and E.F. van Dishoeck7,8 1 Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monteporzio Catone, Italy 2 Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Florence, Italy 3 LERMA, Observatoire de Paris, UMR 8112 of the CNRS, 61 Av. de L’Observatoire, 75014 Paris, France 4 Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian Qu, 100871 Beijing, P.R. China 5 Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden 6 Observatorio Astron´omico Nacional (IGN), Alfonso XII 3, E-28014 Madrid, Spain 7 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 8 Max Planck Institut f¨ur Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany E-mail contact: gina.santangelo at oa-roma.inaf.it

In the framework of the Water In Star-forming regions with Herschel (WISH) key program, several H2O (Eu > 190 K), high-J CO, [Oi], and OH transitions are mapped with Herschel-PACS in two shock positions along two prototypical outflows around the low-luminosity sources L1448 and L1157. Previous Herschel-HIFI H2O observations (Eu = 53 − 249 K) are also used. The aim is to derive a complete picture of the excitation conditions at the selected shock positions. We adopted a large velocity gradient analysis (LVG) to derive the physical parameters of the H2O and CO emitting gas. Complementary Spitzer mid-IR H2 data were used to derive the H2O abundance.

Consistent with other studies, at all selected shock spots a close spatial association between H2O, mid-IR H2, and high-J CO emission is found, whereas the low-J CO emission traces either entrained ambient gas or a remnant of an older shock. The excitation analysis, conducted in detail at the L1448-B2 position, suggests that a two-component model is needed to reproduce the H2O, CO, and mid-IR H2 lines: an extended warm component (T ∼ 450 K) is traced by the H2O emission with Eu = 53 − 137 K and by the CO lines up to J = 22 − 21, and a compact hot component (T = 1100 K) is traced by the H2O emission with Eu > 190 K and by the higher-J CO transitions. At L1448-B2 we −6 −5 obtain an H2O abundance (3 − 4) × 10 for the warm component and (0.3 − 1.3) × 10 for the hot component and a CO abundance of a few 10−5 in both components. In L1448-B2 we also detect OH and blue-shifted [Oi] emission, spatially coincident with the other molecular lines and with [Feii] emission. This suggests a dissociative shock for these species, related to the embedded atomic jet. On the other hand, a non-dissociative shock at the point of impact of the jet on the cloud is responsible for the H2O and CO emission. The other examined shock positions show an H2O excitation similar to L1448-B2, but a slightly higher H2O abundance (a factor of ∼ 4). The two gas components may represent a gas stratification in the post-shock region. The extended and low-abundance warm component traces the post-shocked gas that has already cooled down to a few hundred Kelvin, whereas the compact and possibly higher-abundance hot component is associated with the gas that is currently undergoing a shock episode. This hot gas component is more affected by evolutionary effects on the timescales of the outflow propagation, which explains the observed H2O abundance variations. Accepted by Accepted for publication in Astronomy and Astrophysics http://arxiv.org/pdf/1307.2627

36 The long wavelength view of GG Tau A: Rocks in the Ring World Anna M.M. Scaife Department of Physics & Astronomy, University of Southampton, Higheld, Southampton, SO17 1BJ E-mail contact: a.scaife at soton.ac.uk We present the first detection of GG Tau A at centimeter-wavelengths, made with the Arcminute Microkelvin Imager Large Array (AMI-LA) at a frequency of 16 GHz (λ = 1.8 cm). The source is detected at > 6 σrms with an integrated flux density of S = 249±45 µJy. We use these new centimetre-wave data, in conjunction with additional measurements compiled from the literature, to investigate the long wavelength tail of the dust emission from this unusual proto- planetary system. We use an MCMC based method to determine maximum likelihood parameters for a simple parametric spectral model and consider the opacity and mass of the dust contributing to the microwave emission. We derive a dust mass of approximately 0.1 M⊙, constrain the dimensions of the emitting region and find that the opacity index at λ > 7mm is less than unity, implying a contribution to the dust population from grains exceeding 4 cm in size. We suggest that this indicates coagulation within the GG Tau A system has proceeded to the point where dust grains have grown to the size of small rocks with dimensions of a few centimetres. Considering the relatively young age of the GG Tau association, in combination with the low derived disk mass, we suggest that this system may provide a useful test case for rapid core accretion planet formation models. Accepted by MNRAS http://arxiv.org/pdf/1307.5146

New companions in the stellar systems of DI Cha, Sz 22, CHXR 32, and Cha Hα 5 in the Cha I star-forming region T.O.B. Schmidt1, N. Vogt2, R. Neuh¨auser1, A. Bedalov1,3, and T. Roell1 1 Astrophysikalisches Institut und Universit¨ats-Sternwarte, Universit¨at Jena, Schillerg¨aßchen 2-3, 07745 Jena, Ger- many 2 Departamento de F´ısica y Astronom´ıa, Universidad de Valpara´ıso, Avenida Gran Breta˜na 1111, Valpara´ıso, Chile 3 Faculty of Natural Sciences, University of Split, Teslina 12. 21000 Split, Croatia E-mail contact: tobi at astro.uni-jena.de The star-forming regions in Chamaeleon (Cha) are among the nearest (distance ∼165 pc) and youngest (age ∼2 Myrs) conglomerates of recently formed stars and among the ideal targets for studies of star formation. We search for new, hitherto unknown binary or multiple-star components and investigate their membership in Cha and their gravitationally bound nature. We used the NACO instrument at the VLT UT 4/YEPUN of the Paranal Observatory, at 2 or 3 different epochs, in order to obtain relative and absolute astrometric measurements, as well as differential photometry in the J, H, and Ks band. On the basis of known proper motions and these observations, we analysed the astrometric results in proper motion diagrams to eliminate possible (non-moving) background stars and establish co-moving binaries and multiples. DI Cha turns out to be a quadruple system with a hierachical structure, consisting of two binaries: a G2/M6 pair and a co-moving pair of two M5.5 dwarfs. For both pairs we detected orbital motion (P∼130 and ∼65 years), although in opposite directions. Sz 22 is a binary whose main component is embedded in a circumstellar disc or reflection nebula, accompanied by a co-moving M4.5 dwarf. CHXR 32 is a triple system, consisting of a single G5 star, weakened by an edge-on disc and a co-moving pair of M1/M3.5 dwarfs whose components show significant variations in their angular separation. Finally, Cha Hα 5 is a binary consisting of two unresolved M6.5 dwarfs whose strong variations in position angle at its projected separation of only 8 AU imply an orbital period of ∼46 years. DI Cha D and Cha Hα 5 A&B are right at the stellar mass limit and could possibly be brown dwarfs. In spite of various previously published studies of the star-forming regions in Cha we found four hitherto unknown components in young low-mass binaries and multiple systems. (abridged) Accepted by A&A http://arxiv.org/pdf/1307.1082

37 HST FUV imaging of DG Tau: Fluorescent molecular hydrogen emission from the wide angle outflow P.C. Schneider1, J. Eisl¨offel2, M. G¨udel3, H.M. G¨unther4, G. Herczeg5, J. Robrade1, and J.H.M.M. Schmitt1 1 Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg 2 Th¨uringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany 3 Universit¨at Wien, Dr.-Karl-Lueger-Ring 1, 1010 Wien, Austria 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 5 The Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian Qu, Beijing 100871, China E-mail contact: cschneider at hs.uni-hamburg.de One of the best-studied jets from all young stellar objects is the jet of DG Tau, which we imaged in the FUV with HST for the first time. These high spatial resolution images were obtained with long-pass filters and allow us to construct images tracing mainly molecular hydrogen and C IV emission. We find that the H2 emission appears as a limb-brightened cone with additional emission close to the jet axis. The length of the rims is about 0′′. 3 or 42 AU (proj.) before their brightness strongly drops, and the opening angle is about 90◦. Comparing our FUV data with near-IR data we find that the fluorescent H2 emission likely traces the outer, cooler part of the disk wind while an origin of the H2 emission in the surface layers (atmosphere) of the (flared) disk is unlikely. Furthermore, the spatial shape of the H2 emission shows little variation over six years which suggests that the outer part of the disk wind is rather stable and probably not associated with the formation of individual knots. The C IV image shows that the emission is concentrated towards the jet axis. We find no indications for additional C IV emission at larger distances, which strengthens the association with the X-ray emission observed to originate within the DG Tau jet. Accepted by A&A http://arxiv.org/pdf/1307.2846

The low-mass stellar population in the young cluster Tr37: Disk evolution, accretion, and environment A. Sicilia-Aguilar1, J. S. Kim2, A. Sobolev3, K. Getman4, Th. Henning5 and M. Fang1 1 Departamento de F´ısica Te´orica, Facultad de Ciencias, Universidad Aut´onoma de Madrid, 28049 Cantoblanco, Madrid, Spain 2 Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 3 Astronomical Observatory, Ural Federal University, Lenin Avenue 51, 620000 Ekaterinburg, Russia 4 Department of Astronomy & Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park PA 16802 5 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69117 Heidelberg, Germany E-mail contact: aurora.sicilia at uam.es We present a study of accretion and protoplanetary disks around M-type stars in the 4 Myr-old cluster Tr37. With a well-studied solar-type population, Tr37 is a benchmark for disk evolution. We used low-resolution spectroscopy to identify and classify 141 members (78 new ones) and 64 probable members, mostly M-type stars. Hα emission provides information about accretion. Optical, 2MASS, Spitzer, and WISE data are used to trace the SEDs and search for disks. We construct radiative transfer models to explore the structures of full-disks, pre-transition, transition, and dust-depleted disks. Including the new members and the known solar-type stars, we confirm that a substantial fraction (∼2/5) of disks show signs of evolution, either as radial dust evolution (transition/pre-transition disks) or as a more global evolution (with low small-dust masses, dust settling, and weak/absent accretion signatures). Accretion is strongly dependent on the SED type. About half of the transition objects are consistent with no accretion, and dust-depleted disks have weak (or undetectable) accretion signatures, especially among M-type stars. The analysis of accretion and disk structure suggests a parallel evolution of dust and gas. We find several distinct classes of evolved disks, based on SED type and accretion status, pointing to different disk dispersal mechanisms and probably different evolutionary paths. Dust depletion and opening of inner holes appear to be independent processes: most transition disks are not dust-depleted, and most dust-depleted disks do not require inner holes. The differences in disk structure

38 between M-type and solar-type stars in Tr37 (4 Myr old) are not as remarkable as in the young, sparse, Coronet cluster (1-2 Myr old), suggesting that other factors, like the environment/interactions in each cluster, are likely to play an important role in the disk evolution and dispersal. Finally, we also find some evidence of clumpy star formation or mini-clusters within Tr37. Accepted by A&A http://arxiv.org/pdf/1308.0114 http://astro.ft.uam.es/aurora/aurora_publications.html

ATLASGAL — properties of compact H ii regions and their natal clumps J. S. Urquhart1, M. A. Thompson2, T. J. T. Moore3, C. R. Purcell4, M. G. Hoare4, F. Schuller5, F. Wyrowski1, T. Csengeri1, K. M. Menten1, S. L. Lumsden4, S. Kurtz6, C. M. Walmsley7,8, L. Bronfman9, L. K. Morgan3, D.J.Eden3 and D.Russeil10 1 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, Bonn, Germany 2 Science and Technology Research Institute, University of Hertfordshire, College Lane, Hatfield, AL10 9AB, UK 3 Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birken- head, CH41 1LD, UK 4 School of Physics and Astrophysics, University of Leeds, Leeds, LS29JT, UK 5 European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile 6 Centro de Radioastronomia y Astrofisica, Universidad Nacional Aut´onoma de M´exico, Antigua Carretera a Ptzcuaro # 8701 Morelia, 58089 Michoac´an, M´exico 7 Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, 50125 Firenze, Italy 8 Dublin Institute for Advanced Studies, Burlington Road 10, Dublin 4, Ireland 9 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 10 Aix Marseille Universit´e, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388, Marseille, France E-mail contact: jurquhart at mpifr-bonn.mpg.de We present a complete sample of molecular clumps containing compact and ultra-compact (UC) H ii regions between ℓ = 10◦ and 60◦ and |b| < 1◦, identified by combining the the ATLASGAL sub-mm and CORNISH radio continuum surveys with visual examination of archival infrared data. Our sample is complete to optically thin, compact and UC H ii regions driven by a zero age main sequence star of spectral type B0 or earlier embedded within a 1,000 M⊙ clump. In total we identify 213 compact and UC H ii regions, associated with 170 clumps. Unambiguous kinematic distances are derived for these clumps and used to estimate their masses and physical sizes, as well as the Lyman continuum fluxes and sizes of their embedded H ii regions. We find a clear lower envelope for the surface density of molecular clumps hosting massive star formation of 0.05 g cm−2, which is consistent with a similar sample of clumps associated with 6.7GHz masers. The mass of the most massive embedded stars is closely correlated with the mass of their natal clump. Young B stars appear to be significantly more luminous in the ultraviolet than predicted by current stellar atmosphere models. The properties of clumps associated with compact and UC H ii regions are very similar to those associated with 6.7GHz methanol masers and we speculate that there is little evolution in the structure of the molecular clumps between these two phases. Finally, we identify a significant peak in the surface density of compact and UC H ii regions associated with the W49A star-forming complex, noting that this complex is truly one of the most massive and intense regions of star formation in the Galaxy. Accepted by MNRAS http://arxiv.org/pdf/1307.4105

ATLASGAL — Environments of 6.7 GHz methanol masers J. S. Urquhart1, T. J. T. Moore2, F. Schuller3, F. Wyrowski1, K. M. Menten1, M. A. Thompson4, T. Csengeri1, C. M. Walmsley5,6, L. Bronfman7 and C. K¨onig1 1 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, Bonn, Germany 2 Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birken-

39 head, CH41 1LD, UK 3 European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile 4 Science and Technology Research Institute, University of Hertfordshire, College Lane, Hatfield, AL10 9AB, UK 5 Osservatorio Astrofisico di Arcetri, Largo E. Fermi, 5, 50125 Firenze, Italy 6 Dublin Institute for Advanced Studies, Burlington Road 10, Dublin 4, Ireland 7 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile E-mail contact: jurquhart at mpifr-bonn.mpg.de Using the 870-µm APEX Telescope Large Area Survey of the Galaxy (ATLASGAL), we have identified 577 submil- limetre continuum sources with masers from the methanol multibeam (MMB) survey in the region 280◦ <ℓ< 20◦; | b | < 1.5◦. 94percent of methanol masers in the region are associated with sub-millimetre dust emission. We estimate masses for ∼450 maser-associated sources and find that methanol masers are preferentially associated with massive clumps. These clumps are centrally condensed, with envelope structures that appear to be scale-free, the mean maser position being offset from the peak column density by 0 ± 4′′. Assuming a Kroupa initial mass function and a star- formation efficiency of ∼30 per cent, we find that over two thirds of the clumps are likely to form clusters with masses >20 M⊙. Furthermore, almost all clumps satisfy the empirical mass-size criterion for massive star formation. Bolo- 6 metric luminosities taken from the literature for ∼100 clumps range between ∼100 and 10 L⊙. This confirms the link between methanol masers and massive young stars for 90percent of our sample. The Galactic distribution of sources suggests that the star-formation efficiency is significantly reduced in the Galactic-centre region, compared to the rest of the survey area, where it is broadly constant, and shows a significant drop in the massive star-formation rate density in the outer Galaxy. We find no enhancement in source counts towards the southern Scutum-Centaurus arm tangent at ℓ ∼ 315◦, which suggests that this arm is not actively forming stars. Accepted by MNRAS http://arxiv.org/pdf/1302.2538 http://adsabs.harvard.edu/abs/2013MNRAS.431.1752U

Simulations of protostellar collapse using multigroup radiation hydrodynamics. II. The second collapse Neil Vaytet1, Gilles Chabrier1,2, Edouard Audit3,4, Benoit Commercon5, Jacques Masson1, Jason Ferguson6 and Franck Delahaye7 1 Ecole´ Normale Sup´erieure de Lyon, CRAL, UMR CNRS 5574, Universit´eLyon I, 46 All´ee d’Italie, 69364 Lyon Cedex 07, France 2 School of Physics, University of Exeter, Exeter, EX4 4QL, UK 3 Maison de la Simulation, USR 3441, CEA - CNRS - INRIA - Universit´eParis-Sud - Universit´ede Versailles, 91191 Gif-sur-Yvette, France 4 CEA/DSM/IRFU, Service d’Astrophysique, Laboratoire AIM, CNRS, Universit´eParis Diderot, 91191 Gif-sur- Yvette, France 5 Laboratoire de radioastronomie, (UMR CNRS 8112), Ecole´ normale sup´erieure et Observatoire de Paris, 24 rue Lhomond, 75231 Paris Cedex 05, France 6 Department of Physics, Wichita State University, Wichita, KS 67260-0032, USA 7 LERMA, Observatoire de Paris, ENS, UPMC, UCP, CNRS, 5 Place Jules Janssen, 92190 Meudon, France E-mail contact: neil.vaytet at ens-lyon.fr Star formation begins with the gravitational collapse of a dense core inside a molecular cloud. As the collapse progresses, the centre of the core begins to heat up as it becomes optically thick. The temperature and density in the centre eventually reach high enough values where fusion reactions can ignite; the protostar is born. This sequence of events entail many physical processes, of which radiative transfer is of paramount importance. Many simulations of protostellar collapse make use of a grey treatment of radiative transfer coupled to the hydrodynamics. However, interstellar gas and dust opacities present large variations as a function of frequency. In this paper, we follow-up on a previous paper on the collapse and formation of Larson’s first core using multigroup radiation hydrodynamics (Paper I) by extending the calculations to the second phase of the collapse and the formation of Larson’s second core. We have made the use of a non-ideal gas equation of state as well as an extensive set of spectral opacities in a spherically symmetric fully implicit Godunov code to model all the phases of the collapse of a 0.1, 1 and 10 M⊙

40 cloud cores. We find that, for a same central density, there are only small differences between the grey and multigroup simulations. The first core accretion shock remains supercritical while the shock at the second core border is found to be strongly subcritical with all the accreted energy being transfered to the core. The size of the first core was found to vary somewhat in the different simulations (more unstable clouds form smaller first cores) while the size, mass and temperature of the second cores are independent of initial cloud mass, size and temperature. Our simulations support the idea of a standard (universal) initial second core size of 0.003 AU and mass 0.0014 M⊙. Accepted by A&A http://arxiv.org/pdf/1307.1010

The effect of episodic accretion on the phase transition of CO and CO2 in low-mass star formation Eduard I. Vorobyov1, I. Baraffe2, T. Harries2 and G. Chabrier3 1 Institute of Astrophysics, University of Vienna, Vienna 1170, Austria 2 University of Exeter, Physics and Astronomy, Stocker Road, EX4 4QL Exeter, UK 3 Ecole´ Normale Sup´erieure, Lyon, CRAL (UMR CNRS 5574), Universit´ede Lyon, France E-mail contact: eduard.vorobiev at univie.ac.at

We study the evaporation and condensation of CO and CO2 during the embedded stages of low-mass star formation by using numerical simulations. We focus on the effect of luminosity bursts, similar in magnitude to FUors and EXors, on the gas-phase abundance of CO and CO2 in the protostellar disk and infalling envelope. The evolution of a young protostar and its environment is followed based on hydrodynamical models using the thin-disk approximation, coupled with a stellar evolution code and phase transformations of CO and CO2. The accretion and associated luminosity bursts in our model are caused by disk gravitational fragmentation followed by quick migration of the fragments onto the forming protostar. We found that bursts with luminosity on the order of 100–200 L⊙ can evaporate CO ices in part of the envelope. The typical freeze-out time of the gas-phase CO onto dust grains in the envelope (a few kyr) is much longer than the burst duration (100–200 yr). This results in an increased abundance of the gas-phase CO in the envelope long after the system has returned into a quiescent stage. In contrast, luminosity bursts can evaporate CO2 ices only in the disk, where the freeze-out time of the gas-phase CO2 is comparable to the burst duration. We thus confirm that luminosity bursts can leave long-lasting traces in the abundance of gas-phase CO in the infalling envelope, enabling the detection of recent bursts as suggested by previous semi-analytical studies. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1307.2271

Three-Dimensional Radiation Transfer in Young Stellar Objects B.A. Whitney1,2, T.P. Robitaille3, J.E. Bjorkman4, R. Dong5, M.J. Wol2, K. Wood6, and J. Honor1 1 University of Wisconsin, 475 N. Charter St., Madison, WI 53706 2 Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 3 Max-Planck-Institute for Astronomy, K¨onigstuhl 17, 69117 Heidelberg, Germany 4 Ritter Observatory, MS 113, Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606-3390 5 Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 6 School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9AD E-mail contact: bwhitney at astro.wisc.edu We have updated our publicly available dust radiative transfer code (HOCHUNK3D) to include new emission processes and various 3-D geometries appropriate for forming stars. The 3-D geometries include warps and spirals in disks, accretion hotspots on the central star, fractal clumping density enhancements, and misaligned inner disks. Additional axisymmetric (2-D) features include gaps in disks and envelopes, ”puffed-up inner rims” in disks, multiple bipolar cavity walls, and iteration of disk vertical structure assuming hydrostatic equilibrium. We include the option for simple power-law envelope geometry, which combined with fractal clumping, and bipolar cavities, can be used to

41 model evolved stars as well as protostars. We include non-thermal emission from PAHs and very small grains, and external illumination from the interstellar radiation field. The grid structure was modified to allow multiple dust species in each cell; based on this, a simple prescription is implemented to model dust stratification. We describe these features in detail, and show example calculations of each. Some of the more interesting results include the following: 1) Outflow cavities may be more clumpy than infalling envelopes. 2) PAH emission in high- mass stars may be a better indicator of evolutionary stage than the broadband SED slope; and related to this, 3) externally illuminated clumps and high-mass stars in optically thin clouds can masquerade as YSOs. 4) Our hydrostatic equilibrium models suggest that dust settling is likely ubiquitous in T Tauri disks, in agreement with previous observations. Accepted by ApJS http://arxiv.org/pdf/1307.0561

A SCUBA-2 850 µm survey of protoplanetary discs in the σ Orionis cluster Jonathan P. Williams1, Lucas A. Cieza,1, Sean M. Andrews2, Iain M. Coulson3, Amy J. Barger4,5, Caitlin M. Casey1, Chian-Chou Chen1, Lennox L. Cowie1, Michael Koss1, Nicholas Lee1 and David B. Sanders1 1 Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96816 USA 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 3 Joint Astronomy Centre, 660 N. Aohoku Place, University Park, Hilo, HI 96 720, USA 4 Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706, USA 5 Department of Physics and Astronomy, University of Hawaii, 2505 Correa Road, Honolulu, HI 96822, USA E-mail contact: jpw at ifa.hawaii.edu We present the results from a large 850 µm survey of the σ Orionis cluster using the SCUBA-2 camera on the James Clerk Maxwell Telescope. The 0.5◦ diameter circular region we surveyed contains 297 young stellar objects with an age estimated at about 3Myr. We detect 9 of these objects, 8 of which have infrared excesses from an inner disc. We also serendipitously detect 3 non-stellar sources at > 5σ that are likely background submillimetre galaxies. The 9 detected stars have inferred disc masses ranging from 5 to about 17 MJup, assuming similar dust properties as Taurus discs and an ISM gas-to-dust ratio of 100. There is a net positive signal toward the positions of the individually undetected infrared excess sources indicating a mean disc mass of 0.5 MJup. Stacking the emission toward those stars without infrared excesses constrains their mean disc mass to less than 0.3 MJup, or an equivalent Earth mass in dust. The submillimetre luminosity distribution is significantly different from that in the younger Taurus region, indicating disc mass evolution as star forming regions age and the infrared excess fraction decreases. Submillimeter Array observations reveal CO emission toward 4 sources demonstrating that some, but probably not much, molecular gas remains in these relatively evolved discs. These observations provide new constraints on the dust and gas mass of protoplanetary discs during the giant planet building phase and provide a reference level for future studies of disc evolution. Accepted by MNRAS http://arxiv.org/pdf/1307.7174

Deep observations of O2 toward a low-mass protostar with Herschel Umut A. Yıldız1, Kinsuk Acharyya2, Paul F. Goldsmith3, Ewine F. van Dishoeck1,4, Gary Melnick5, Ronald Snell6, Ren´eLiseau7, Jo-Hsin Chen3, Laurent Pagani8, Edwin Bergin9, Paola Caselli10,11, Eric Herbst12, Lars E. Kristensen5, Ruud Visser9, Dariusz C. Lis13 and Maryvonne Gerin14 1 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 2 S.N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata, 700098, India 3 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena CA, 91109, USA 4 Max Planck Institut f¨ur Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 6 Department of Astronomy, LGRT 619, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003, USA

42 7 Dept. of Earth & Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-439 92 Onsala, Sweden 8 LERMA & UMR8112 du CNRS, Observatoire de Paris, 61 Av. de l’Observatoire, 75014, Paris, France 9 Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042, USA 10 School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK 11 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy 12 Departments of Chemistry, Astronomy, and Physics, The University of Virginia, Charlottesville, Virginia, USA 13 California Institute of Technology, Cahill Center for Astronomy and Astrophysics 301-17, Pasadena, CA 91125, USA 14 LRA/LERMA, CNRS, UMR8112, Observatoire de Paris & Ecole´ Normale Sup´erieure, 24 rue Lhomond, 75231 Paris Cedex 05, France E-mail contact: yildiz at strw.leidenuniv.nl

Context: According to traditional gas-phase chemical models, O2 should be abundant in molecular clouds, but until recently, attempts to detect interstellar O2 line emission with ground- and space-based observatories have failed. Aims: Following the multi-line detections of O2 with low abundances in the Orion and ρ Oph A molecular clouds with Herschel, it is important to investigate other environments, and we here quantify the O2 abundance near a solar-mass protostar. Methods: Observations of molecular oxygen, O2, at 487 GHz toward a deeply embedded low-mass Class 0 protostar, NGC 1333-IRAS 4A, are presented, using the Heterodyne Instrument for the Far Infrared (HIFI) on the Herschel Space Observatory. Complementary data of the chemically related NO and CO molecules are obtained as well. The high spectral resolution data are analyzed using radiative transfer models to infer column densities and abundances, and are tested directly against full gas-grain chemical models. Results: The deep HIFI spectrum fails to show O2 at the velocity of the dense protostellar envelope, implying one −9 of the lowest abundance upper limits of O2/H2 at ≤6×10 (3σ). The O2/CO abundance ratio is less than 0.005. However, a tentative (4.5σ) detection of O2 is seen at the velocity of the surrounding NGC 1333 molecular cloud, shifted by 1 km s−1 relative to the protostar. For the protostellar envelope, pure gas-phase models and gas-grain chemical models require a long pre-collapse phase (∼0.7–1×106 years), during which atomic and molecular oxygen are frozen out onto dust grains and fully converted to H2O, to avoid overproduction of O2 in the dense envelope. The same model also reproduces the limits on the chemically related NO molecule if hydrogenation of NO on the grains to more complex molecules such as NH2OH, found in recent laboratory experiments, is included. The tentative detection of O2 in the surrounding cloud is consistent with a low-density PDR model with small changes in reaction rates. Conclusions: The low O2 abundance in the collapsing envelope around a low-mass protostar suggests that the gas and ice entering protoplanetary disks is very poor in O2. Accepted by Astronomy & Astrophysics http://adsabs.harvard.edu/abs/2013arXiv1307.8031Y

43 Dissertation Abstracts

Surveying Star Formation in the Galaxy

Adam Ginsburg

Thesis work conducted at: Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, Colorado, USA Current address: 391 UCB Boulder, CO, USA 80309 Address as of October 2013: Karl-Schwarzschild-Strasse 2, 85748 Garching bei M¨unchen, Germany Electronic mail: adam.g.ginsburg at gmail.com Ph.D dissertation directed by: John Bally Ph.D degree awarded: April 2013

I studied the formation of massive stars and clusters via millimeter, radio, and infrared observations. The Bolocam Galactic Plane Survey (BGPS) was the first millimeter-wave blind survey of the plane of our Galaxy. I wrote the data reduction pipeline for this survey and produced the final publicly released data products. I ran extensive tests of the pipeline, using simulations to probe its performance. The BGPS detected over 8000 1.1 mm sources, the largest sample at this wavelength ever detected. As a single- wavelength continuum survey, the BGPS serves as a finder chart for millimeter and radio observations. I therefore performed follow-up surveys of BGPS sources in CO 3-2 and formaldehyde, and others did similar follow-ups to measure velocities and distances towards these sources. Formaldehyde observations of ultracompact HII regions and other millimeter-bright sources were used to measure the local molecular gas density. These measurements hint that density within molecular clouds does not follow a simple > 4 −3 lognormal distribution. They also show that star-forming clouds all contain gas at density ∼10 cm . I used the BGPS source catalog to identify the most massive compact clumps within the galaxy, identifying 18 with 4 masses M > 10 M⊙ in the first quadrant of the Galactic plane. As these objects are all actively star-forming, the < starless timescale of massive proto-cluster clumps must be relatively short, with lifetimes ∼0.6 Myr.

44 Meetings

The Orion Nebula Cluster as a Paradigm for Star Formation a Space Telescope Science Institute mini-workshop Baltimore, MD, October 14-16, 2013

Objective: As the nearest young cluster dominated by massive OB stars, the Orion Nebula Cluster plays a paradigmatic role in our understanding of star and planet formation. The wealth of ground-based and HST data collected in recent years is allowing to study with unprecedented detail the products of the star formation process: stellar mass distribution, age spread, mutiplicity, activity, cluster’s spatial and kinematic structure, etc. These data provide a fundamental reference for comparison with other regions, as well as a critical benchmark for theoretical models and numerical simulations. This workshop is an opportunity to discuss what we have learned from Orion so far, focusing on open problems and new directions of observational and theoretical research. Emphasis will be given to the role played by the Orion Nebula Cluster as a paradigm for the early solar environment, as well as for present-day star formation in different environments, including the Galactic center and the Magellanic Clouds. Organizing Committee: Massimo Robberto, STScI (Chair) Nicola Da Rio, U. Florida Selma de Mink, Carnegie/Caltech & Princeton Mario Gennaro, STScI Lee Hartmann, University of Michigan Lynne A. Hillenbrand, Caltech Dave Soderblom, STScI Jonathan Tan, U. Florida Sherita Hanna (administrative support, [email protected]) http://www.stsci.edu/institute/conference/orion/

45 Characterizing Planetary Systems Across the HR Diagram 28 July - 1 August 2014 – Cambridge, United Kingdom

The University of Cambridge Institute of Astronomy will host a 5 day scientific meeting to further our understanding of the formation and evolution of planetary systems. The meeting will focus on the full lifetime of planetary systems, from pre- to post-main sequence host star stages, and the connections that can be made by viewing these evolutionary stages as parts of a whole. In this way, the program aims to provide an integrative approach rather than focusing on each stellar stage separately. We will bring together participants from the growing diversity of planetary science disciplines: star-planet formation, solar system studies, exoplanets, debris disks, host star abundances and atmospheric pollution, stellar evolution, and planetary dynamics. The conference can accommodate up to 150 people. The overall goal of the meeting is to generate discussion and increase scientific interactions among the diverse com- munities interested in the formation, architecture, and evolution of planetary systems. Two themes that represent the spirit of the meeting are: 1) The physical and chemical connections between evolved planetary systems, their main-sequence counterparts, and those forming in proto-planetary disks. 2) The scientific potential for extracting planetary system frequency, structure, chemistry, and dynamics at different evolutionary phases and stellar populations. Session Topics will include: - Proto-planetary disk and planetary atmosphere chemistry - Planetesimal and solid planet compositions - Planet and debris populations - Host star elemental abundances and pollution - Planetary system and host star evolution We hope to see you in Cambridge next summer! SOC and LOC Contact: [email protected] http://www.ast.cam.ac.uk/meetings/2013/AcrossHR

46 Meetings of Possible Interest

IAUS 302 - Magnetic Fields Throughout Stellar Evolution 26 - 30 August 2013 Biarritz, France http://iaus302.sciencesconf.org Meteoroids 2013. An International Conference on Minor Bodies in the Solar System 26 - 30 August 2013 Dep. of Physics, A.M. University, Poznan, Poland http://www.astro.amu.edu.pl/Meteoroids2013/index.php Exoplanets and Brown Dwarfs 2 - 5 September 2013 de Havilland, University of Hertfordshire, Hatfield, Nr. London, UK no web site yet Evolution of Star Clusters: From Star Formation to Cosmic Ages 24 - 27 September 2013 Splinter Meeting E at the Annual Meeting of the Astronomische Gesellschaft, T¨ubingen, Germany http://www-astro.physik.tu-berlin.de/~harfst/AG2013_SplinterE/ Dust Radiative Transfer - Codes and Benchmarks 9 - 11 October 2013 http://ipag.osug.fr/RT13/index.php The Orion Nebula Cluster as a Paradigm for Star Formation 14 - 16 October 2013 STScI, Baltimore, USA no web site yet 400 Years of Stellar Rotation 17 - 22 November 2013, Natal, Brazil http://www.dfte.ufrn.br/400rotation/ The Life Cycle of Dust in the Universe: Observations, Theory, and Laboratory Experiments 18 - 22 November 2013 Taipei, Taiwan http://events.asiaa.sinica.edu.tw/meeting/20131118/ An Olympian Symposium for Star Formation 26 - 30 May 2014 Paralia Katerinis, Mount Olympus, Greece http://zuserver2.star.ucl.ac.uk/$\sim$tb/ 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

47 Living Together: Planets, Stellar Binaries and Stars with Planets 8 - 12 September 2014 Litomysl Castle, Litomysl, Czech Republic http://astro.physics.muni.cz/kopal2014/ Planet Formation and Evolution 2014 10 - 12 September 2014 Kiel, Germany http://www1.astrophysik.uni-kiel.de/$\sim$2014/main/ 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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