THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 250 — 10 October 2013 Editor: Bo Reipurth ([email protected]) List of Contents

The Star Formation Newsletter Interview ...... 3 My Favorite Object ...... 5 Editor: Bo Reipurth [email protected] Perspective ...... 9

Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers ...... 13 [email protected] Abstracts of Newly Accepted Major Reviews . 51 Technical Assistant: Hsi-Wei Yen Dissertation Abstracts ...... 52 [email protected] New Jobs ...... 54

Editorial Board Meetings ...... 57 Summary of Upcoming Meetings ...... 59 Joao Alves Alan Boss Short Announcements ...... 60 Jerome Bouvier Lee Hartmann Thomas Henning Paul Ho Cover Picture Jes Jorgensen Charles J. Lada The image shows the reflection nebula NGC 7129 Thijs Kouwenhoven located in the Cepheus Flare at a distance of ap- Michael R. Meyer proximately 1250 pc and illuminated by three B- Ralph Pudritz stars. The Herbig Ae/Be star LkHα 234 is the Luis Felipe Rodr´ıguez bright nebulous star partly embedded in the cav- Ewine van Dishoeck ity rim (left of center). The main illuminators of Hans Zinnecker the reflection nebula are the two young B-stars BD+65◦1637 and BD+65◦1638 located inside the The Star Formation Newsletter is a vehicle for cavity (middle of figure). Numerous red Herbig- fast distribution of information of interest for as- Haro objects are seen, particularly the bright bow- tronomers working on star and planet formation shaped HH 103 (near the lower right edge). The and molecular clouds. You can submit material region is rich in low-mass pre-main sequence stars, for the following sections: Abstracts of recently radio continuum sources, and water masers. The B- accepted papers (only for papers sent to refereed stars have blown a cavity in a dense molecular cloud journals), Abstracts of recently accepted major re- about 11 pc in extent. Two molecular outflows are views (not standard conference contributions), Dis- associated with LkHα 234 and an embedded far- sertation Abstracts (presenting abstracts of new infrared source FIRS 2. Ph.D dissertations), Meetings (announcing meet- Image courtesy Johannes Schedler ings broadly of interest to the star and planet for- http://panther-observatory.com 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- Submitting your abstracts ally, the Newsletter brings short overview articles on objects of special interest, physical processes or Latex macros for submitting abstracts theoretical results, the early solar system, as well and dissertation abstracts (by e-mail to as occasional interviews. [email protected]) are appended to each Call for Abstracts. You can also submit via the Newsletter Archive Newsletter web interface at http://www2.ifa. www.ifa.hawaii.edu/users/reipurth/newsletter.htm hawaii.edu/star-formation/index.cfm

2 46/47 outflow. What was the genesis of that paper? John Graham A: At that time, I was on the staff of Cerro Tololo Inter- American Observatory and Bok was coming to Chile on in conversation with Bo Reipurth observing visits. He had renewed his old interest in star formation within dark globules and had obtained a photo- graph of the HH46/47 outflow with the 4-meter telescope there. He was enthusiastic that others should follow up with spectroscopy and infrared photometry to identify the embedded source and to study the outflow. Q: Another very influential paper was your study with Jay Frogel on the new FUor associated with HH 57, and now known as V346 Nor. What is the story behind this discov- ery? A: Every researcher brings his or her own particular ex- pertise to the table. Mine was that I knew the southern skies unusually well and was very aware of any changes that might be taking place. I was familiar with the earlier work of Martin Cohen and Richard Schwartz in survey- Q: Your career started out in Australia where you studied ing areas of recent star formation and one night observing galactic structure. Was this motivated by Bart Bok, who HH 57 I noticed a star-like object that had not been there was the grand old man in that subject in those days? before, in the corner of the HH object. Subsequent com- A: It is important for all young scientists to have a men- munication with Schwartz confirmed that it had not been tor and I was lucky to come of age when Bart Bok had there when he last looked at it. just arrived in Australia as Director of the Mount Stromlo Q: You have documented how reflection nebulae around Observatory. Bart was an amazing character who com- some very young stars vary due to shadowing effects from bined great human warmth with a single-minded passion clouds moving around the stars, probably closer than 1 for his chosen science. Research into the structure of the AU. And you deduced spectroscopically that accretion onto Southern Milky Way was in its infancy at that time and it young stars is clumpy was a ripe field in which to get involved. My own doctoral A: This concerned the reflection nebula associated with research concerned using new distances for young O and the pre-main sequence star R CrA. Almost 100 years ago, early B type stars, some in clusters, some in the field, to Harold Knox-Shaw and Edwin Hubble had observed changes map Galactic spiral structure. in the morphology of the nebula taking place over several Q: Why did you move from Australia to The Netherlands? nights. Hubble correctly deduced that the phenomenon A: I went via South Africa. At the time of my graduation, was due to ’a wave of illumination’ sweeping across struc- the Leiden Observatory was unable to find an astronomer tures in the reflection nebula. I had the advantage of being to staff its southern observing station near Pretoria. The on the scientific staff of an observatory that provided ac- Director, Jan Oort, spoke to Bok, who suggested me as a cess to telescopes on sequential nights and could respond candidate. I took my PhD oral exam there at the Radcliffe to unexpected events at very short notice. Thanks to the Observatory from David Thackeray, who was another of newly available CCD detectors, I was able to image the R my mentors; a personality very different from Bok but CrA reflection nebula on several nights and could docu- who was a person equally passionate about his research. ment changes that could only be due to shadowing effects After a year in South Africa, I joined the staff at Leiden from partially opaque dust clouds very close to the star. but after a year was attracted to the Kitt Peak National The clumpy nature of the circumstellar material could Observatory by David Crawford, who was then in charge also be detected spectroscopically through night-to-night of building the 4-meter Mayall telescope. Kitt Peak was a changes in line intensities. Unfortunately, I was never able great place for a young astronomer in the 1960s because so to correlate the two phenomena. many renowned astronomers passed though there to use Q: Your most cited paper has nothing directly to do with the facilities. star formation, but deals with UBVRI standard stars in Q: You were among the pioneers in the early study of the E-regions. What motivated that study? Herbig-Haro objects and have published numerous papers A: I undertook that work because of the lack of faint pho- on the subject. I particularly remember your paper with tometric standard stars in the southern hemisphere and I Jay Elias from 1983 on the Bok globule harboring the HH needed them for my study of the Cepheid variable stars

3 in the southern galaxy NGC 300. That work led to my participation in the HST key project of using Cepheid variables to determine the distance scale and the Hub- ble constant. It was my one effort in large team research, otherwise I have always preferred to work in teams of two or three people. Q: In your most recent papers you moved to extragalactic star formation, studying young stars in Centaurus A and jets on a vastly larger scale. What were the main results? A: Those were two papers I wrote with Caleb Fassett in which we detailed the star formation that is triggered by the interaction of an extragalactic jet on an adjacent gas cloud. We were able to detect the ageing of the stars as they moved away from the regions of star formation and suggested that they would eventually contribute to the un- resolved, extended envelope of the radio galaxy. I believe that there is a lot more work to be done in examples such as this of star formation taking place under unusual cir- cumstances but I had more or less decided that it was time to stop active astronomical research and to get interested in other things. Towards the end of my scientific career, I took part in two service opportunities. For a year, I became a program officer in the Division of Astronomical Sciences at the Na- tional Science Foundation and, later on, for six years, was Secretary of the American Astronomical Society. While altruism played a part, I found a lot of satisfaction in see- ing for myself how things worked inside each of the two organizations, and I encourage those who can take the time to participate in community activities of this nature. Q: You have recently become interested in science educa- tion for high school students. What are your main moti- vations? A: I feel very strongly that all responsible people should have a basic knowledge of science and the scientific method. To this end, I have become a supporter of the Harry Messel International Science School, which is run by the Univer- sity of Sydney in Australia. The School gives academically gifted high school students the opportunity to become fully immersed in science for two weeks at the University of Sydney, with talks by international science leaders, along with hands-on science activities, and real insights into the methods of current scientific research. This year, the sub- ject was Nanoscience: Small Wonders, Big Future. About 150 students came for a two week residential course from China, India, Japan, New Zealand, Singapore and Thai- land as well as from within Australia. While it is hoped that some of the students will have their interest sparked into a subsequent research career, it is equally important that others go out into their communities to spread the good word about science and what it can do.

4 My Favorite Object The North America Nebula Luisa Rebull

Figure 1: The NAN complex in the optical, with key iden- Introduction tifications. The “North America” part is NGC 7000, the “Pelican” part is IC 5070, and the dark lane is LDN 935. The North America (NGC 7000) and Pelican (IC 5070) Image by Jason Ware. Nebulae, along with the dark lane (LDN 935) between them, have long been a favorite of amateur astronomers; this region has been featured in more than a dozen APODs What is this region? over the years. Figure 1 marks several key features in the image. In the early days of professional astrophotog- The North America Nebula complex (“NAN”) is a com- raphy, Duncan (1923, 1926) took photographic plates of plicated mixed-mode star formation region. NGC 7000, these regions, noting “The plate is filled with a bewildering IC 5070, and LDN 935 are all generally regarded as part amount of detail, both bright and dark.” In some ways, of the same large HII complex (see, e.g., Wendker et al. nothing has changed – images of this region still have a 1983). The NAN is a complicated, kinematically active, bewildering amount of detail. site of star formation with a mass in molecular gas of order 5 Why should we study “yet another star-forming region,” 10 M⊙ (Feldt & Wendker 1993; Bally & Scoville 1980). besides the fact that it is complicated and beautiful? The There are at least 50 Herbig AeBe stars scattered through evidence is mounting that environment matters for star the complex (e.g., Herbig 1958), at least nine embedded or formation – it can affect stellar properties such as stel- partially embedded young clusters (Cambr´esy et al. 2002), lar rotation rates (e.g., Clarke & Bouvier 2000, Briggs et and a variety of other signposts of current star formation, al. 2007), disk evolution timescales (e.g., Robberto et al. such as HH objects and jets, FU Ori objects, and strong 2004), multiplicity (e.g., Kraus & Hillenbrand 2007), and Hα emission line stars (see Reipurth & Schneider 2008 for more. Much of our understanding of the process of low- a review). The few hundred largely unobscured young stel- mass star formation is based on study of nearby molecular lar objects (YSOs) that have been previously identified as cloud complexes, which are primarily lower-mass clouds members of the complex likely range in age from <1 Myr such as Taurus (140 pc; Torres et al. 2007), populated with to several Myr (see Rebull et al. 2011, hereafter R11, for a summary). Based on simple assumptions of the IMF and 300 low-mass (<2 M⊙) young stars (see, e.g., Kenyon ∼et al. 2008 or Rebull et al. 2010). The Orion Nebula Clus- the high-mass star inventory, there should be thousands of ter (ONC; 400 pc; see, e.g., Menten et al. 2007 or Muench low mass classical T Tauri (CTT) and weak-lined T Tauri et al. 2008 or Megeath et al. 2012), is the closest and (WTT) members of the complex. In addition to the unob- therefore the prototypical high mass and high density star scured population, an embedded population was suspected forming region. However, these nearby cloud complexes (e.g., Herbig 1958, Osterbrock 1957). Using more than a million 2MASS sources in a 2.5◦ 2.5◦ region, Cambr´esy provide only snapshots. For a comprehensive understand- × ing of star formation, particularly in regions like Orion, et al. (2002) mapped extinction and reddening toward the NAN, finding visual extinction up to 30 magnitudes, as we need more examples of high mass and high density ∼ star forming regions. well as embedded clusters. Thus, star formation is demon- strably ongoing here. The distance to the NAN is 520 pc ∼

5 based on Laugalys et al. (2006) and Straizys et al. (1989); see discussion in Guieu et al. (2009; hereafter G09). Given that the NAN is the second-closest region of high- density, high-mass star formation, after Orion, to the Earth, it is comparatively under-studied. (Orion has 400+ arti- cles in ADS and the NAN has less than a quarter of that.) The reason? The line of sight to the NAN (l,b=84.8◦, 0.53◦) is not only in the Galactic Plane, but along a spiral− arm. Images of this region are heavily populated with fore- ground and background stars; the contamination is esti- mated at 1900 500 stars deg−2 to the depth of the 2MASS survey (Cambr´esy± et al. 2002).

Finding the members using infrared

One way of identifying members of the NAN as distinct from other stars along the line-of-sight is by looking for those that have the prominent infrared (IR) signatures in- dicative of circumstellar disks. This region of sky was in the few percent missed by the all-sky survey conducted in 1983 by the Infrared Astronomical Satellite (IRAS), but it has been observed by the Midcourse Space Exper- iment (MSX), AKARI, and WISE. However, given the Figure 2: The NAN complex in Spitzer bands (3.6, 4.5, 5.8, high source density and high contamination rate, both 8, and 24 µm). The dark lane in the lower left is the ‘Gulf of Mexico’, the bright arc-like texture in the nebulosity high spatial resolution and deep observations are crucial for extracting candidate cluster members. left of that are the ‘Mexican Riviera’ from Fig. 1; the bright arc-like texture in the upper right is the back of the Our deep Spitzer Space Telescope IRAC and MIPS maps Pelican’s neck from Fig. 1. The dark lane in the upper of a 7 square degree region of the complex were published ∼ right is the “Pelican’s hat” – see R11. Nearly 90 years in R11 (MIPS) and G09 (IRAC); see Figure 2. IRAS and after Duncan (1926), these images still have a ‘bewildering MIPS reveal complex extended emission throughout the amount of detail’! NAN at all wavelengths, in addition to a rich stellar pop- ulation. We combined our Spitzer data with an earlier KPNO 0.9m optical survey, 2MASS near-infrared photo- calculate that there should be a group of up to 8 O stars metric data, IPHAS optical data, and other data from the powering the NAN. The leading literature candidate is a literature to look for objects that had properties consistent single O5 V, 2MASS J205551.25+435224.6 (Comer´on & with membership. As of 2008, there were only 200 iden- Pasquali 2005), located on the edge of LDN935 (A 8- tified young star NAN members (see discussion∼ in R11). V 10 mag) and it may be isolated; Straizys & Laugalys∼ We have now identified 2100 candidate young stellar ob- (2008) find 4 additional later O stars, one apparently close jects (YSOs) based on∼ apparent infrared excess – 10 to this O5 V, that could contribute ionizing flux. The more YSO candidate members than were known before.∼ × Spitzer maps do not particularly clarify whether or not the source(s) are behind the Gulf of Mexico. The limb- Where is the ionizing source? brightened edges of the nebulosity seen in the Spitzer maps appear to be roughly symmetric about the Gulf of Mexico, Many previous authors have sought the ionizing source, or suggesting that perhaps the illuminating source indeed is sources, for the NAN; several articles have proposed vari- behind the Gulf. The O5 V star that is the leading con- ous objects (e.g., Herbig 1958, Osterbrock 1957, Comer´on tender in the literature is located just north of the Gulf & Pasquali 2005), see R11 for a longer discussion of the of Mexico, very roughly at the “Bahamas,” which is also literature, but a brief summary now follows. Opinion roughly consistent with this illumination pattern. has generally wavered between identifying the source(s) as If the driving source here really is dominated by a single somewhere behind the Gulf of Mexico – and thus a chal- O5 star, the NAN is then significantly different than the lenge to recover – or as individual optically visible sources. ONC, where a dense cluster of one late O star and several From an energy budget perspective, Wendker et al. (1983) early B stars powers the nebula.

6 The Gulf of Mexico and other clusters YSOs despite having little or no IR excess. However, there are also several very embedded sources, including notably We find both a distributed population and several dense the extremely embedded object on the lower right (high- clusterings of candidate YSOs that we have named for lighted with a blue pentagon), which is apparently respon- their location in the complex: the Gulf of Mexico, the sible for a significant fraction of the 70 µm flux density in Pelican, and the Pelican’s Hat (just above the Pelican’s the vicinity. The source whose SED is to the left of this head). Most striking is the Gulf of Mexico cluster, which one appears to be extremely reddened but may not have includes 375 YSO candidate members of the cluster (just a substantial circumstellar disk or envelope. 11 of which were previously identified YSOs, largely by This northern-most portion of the Gulf of Mexico cluster Herbig 1958), and surrounds a dramatic sinuous dust lane also includes a variety of jets (Armond et al. 2011, also (see Fig. 2 and Fig. 3), which is dark in portions even at seen at IRAC bands) and a very interesting source, LkHa 70 µm. The dark lane includes peaks of A estimated at v 188-G4 = HBC 722 = PTF 10qpf (see, e.g., Miller et al. 30 mags. At our assumed distance of the NAN, it is 4.5 pc 2011, K´osp´al et al. 2011, and references therein). This (30′) across at its widest part. This region has the widest source is thought to have recently begun a FU Orionis- range in infrared colors of the three clusters, including the like outburst. Before the outburst, it had been identi- largest excesses and by far the most 70 µm point-source fied as a classical TTauri, but it brightened by more than detections in the MIPS map. 4 magnitudes in the optical in 2010. This is the first FU Orionis-type object known that had been reasonably well-characterized pre-outburst. The SED (largely pre- outburst) for this object appears in Figure 4 as the SED on the top (highlighted with a blue pentagon). The SOFIA data presented in this Figure (Rebull et al. in prep.) were taken post-outburst (in 2012), and the MIPS data were pre-outburst (in 2006); the measurements at 24 µm are significantly different because the source itself∼ has changed significantly at these wavelengths. Some of the data identifying this object came from a Palo- mar Transient Factory (PTF) optical monitoring program of this region (Findeisen et al. 2013). This multi-year sur- vey has also revealed a number of other high-amplitude variables such as PTF 10nvg (e.g., Covey et al. 2011, Hillenbrand et al. 2013); this object has undergone a se- ries of brightening and dimming events suggestive of both accretion-driven and extinction-driven variability. Find- Figure 3: The Gulf of Mexico cluster in 24 µm (top left), 70 eisen et al. (2013) find a sample of 41 objects with distinct µm (top right), 160 µm (lower left), and, for comparison, bursting and/or fading behaviors. This data set spans 4+ POSS-red (lower right). The greyscale colors correspond years of monitoring, since Fall 2009 (with some gaps due to a histogram-equalized stretch of surface brightnesses to fires as well as weather). More results are still to come. in each case. The contour (plus YSO candidacy) defines cluster membership, and is essentially the Av=10 contour from the Cambr´esy et al. (2002) extinction map. Coming attractions

In addition to mining the PTF data, we have spectro- Figure 4 presents a selection of 10 spectral energy distribu- scopic follow-up for about 2000 YSO candidates in the tions (SEDs) for some of the objects in the northernmost NAN, selected in a variety of ways. We are working to- Gulf of Mexico. Note the wide range of SED types. Some wards a characterization of the YSO population in this of the least embedded objects in this region are among the region, and from there, we should be able to further inves- few objects known (or suspected) to be cluster members tigate whether (and, if so, how) this region is significantly prior to 2008. These are optically visible, and of the ones different than Orion. Nearly 90 years after Duncan (1926), shown in the figure, these previously-identified sources are images of the NAN still have a ‘bewildering amount of de- generally on the left (literature synonyms included in the tail’, but we are en route to a deeper understanding of this SEDs). Elsewhere in the cluster, there are also photo- region. spheric SEDs – essentially no apparent IR excess – but these are emission line objects, and thus they are likely

7 References: Armond, T., Reipurth, B., Bally, J., Aspin, C. 2011, A&A, 528, A125 Bally, J., & Scoville, N., 1980, ApJ, 239, 121 Briggs, K., G¨udel,M., Telleschi, A., et al. 2007, A&A, 468, 413 Cambr´esy, L., Beichman, C., Jarrett, T., Cutri, R., 2002, AJ, 123, 2559 Clarke, C., & Bouvier, J., 2000, MNRAS, 319, 457 Comer´on, F. & Pasquali, A., 2005, A&A, 430, 541 Covey, K., Hillenbrand, L., Miller, A., et al., 2011, AJ, 141, 40 Duncan, J. C., 1923, ApJ, 57, 137 Duncan, J. C., 1926, ApJ, 63, 122 Feldt, C., and Wendker, H., 1993, A&AS, 100, 287 Findeisen, K., Hillenbrand, L., Ofek, E., Levitan, D., Sesar, B., La- her, R., Surace, J., 2013, ApJ, 768, 93 Guieu, S., Rebull, L. M., Stauffer, J. R., et al., 2009, ApJ, 697, 787 (G09) Herbig, G., 1958, ApJ, 128, 259 Hillenbrand, L., Miller, A., Covey, K., et al., 2013, AJ, 145, 59 Kenyon, S., G´omez, M., & Whitney, B., 2008, in Handbook of Star Forming Regions, Volume I: The Northern Sky, ASP Monograph Publications, vol. 4, Ed. B. Reipurth, p. 405 K´osp´al, A., Abrah´am,´ P., Ar´evalo Morales, M, et al., 2011, A&A, 527, 133 Kraus, A., Hillenbrand, L., 2007, ApJ, 662, 413 Figure 4: Selection of SEDs from the Gulf of Mexico. Cen- tral image: MIPS-24 image of the northernmost clump Laugalys, V., Straizys, V., Vrba, F. J., Boyle, R. P., Philip, A. G. D., & Kazlauskas, A., 2006a, Baltic Astronomy, 15, 483 of YSO candidates in the Gulf of Mexico. The 10 SEDs around the image correspond to objects seen in the MIPS Megeath, S. T., Gutermuth, R., Muzerolle, J., et al., 2012, AJ, 144, 192 image; those also seen in SOFIA data taken of this region Menten, K. M., Reid, M. J., Forbrich, J., & Brunthaler, A. 2007, are indicated by blue circles in the MIPS image. Note the A&A, 474, 515 wide range of SED types. The SED at the top highlighted Miller, A., Hillenbrand, L., Covey, K., et al., 2011, ApJ, 730, 80 with a blue pentagon is the FU Orionis-like outburster (LkHa 188-G4 = HBC 722 = PTF 10qpf); the MIPS (pre- Muench, A., Getman, K., Hillenbrand, L., Preibisch, T., 2008, in Handbook of Star Forming Regions, Volume I: The Northern Sky, outburst) and SOFIA (post-outburst) measurements are ASP Monograph Publications, vol. 4, Ed. B. Reipurth, p. 483 significantly different. The SED at the bottom right high- Osterbrock, D., 1957, ApJ, 125, 622 lighted with a blue pentagon is apparently responsible for Rebull, L., Padgett, D. L., McCabe, C.-E., et al., 2010, ApJS, 186, a significant fraction of the 70 µm flux density in this re- −1 −2 259 gion. λFλ is in erg s cm , and λ is in microns. Vertical Rebull, L., Guieu, S., Stauffer, J., 2011, ApJS, 193, 25 (R11) error bars are typically smaller than the points. Sym- bols denote origin of photometry: =Vilnius system, tri- Reipurth, B., & Schneider, N., 2008, in Handbook of Star Forming × Regions, Volume I: The Northern Sky, ASP Monograph Publica- angles=IPHAS, += other literature, diamonds=2MASS, tions, vol. 4, Ed. B. Reipurth, p. 36 circles=IRAC, squares=MIPS, stars=SOFIA; downward- Robberto, M., Song, J., Mora Carrillo, G., et al., 2004, ApJ, 606, pointing arrows are upper limits. IAU-compliant Spitzer- 952 based names appear in each SED; synonyms from the lit- Straizys, V., & Laugalys, V., 2008, Baltic Astronomy, 17, 143 erature, where relevant, appear in the lower portion of the Straizys, V., Meistas, E., & Vansevicius, V., 1989, Vilnius Observa- SED. tory Bulletin, 83, 3 Torres, R. M., Loinard, L., Mioduszewski, A. J., & Rodr´ıguez, L. F. 2007, ApJ, 671, 1813 Wendker, H., Benz, D., Baars, J., 1983, A&A, 124, 116

8 In contrast, this buildup time is relatively brief in the “fast” route. Here, mass gathers together quickly, i.e., a Perspective pre-existing, diffuse configuration is suddenly compressed. The self-gravity of this material is too great for any coun- Star Formation and tervailing pressure gradient. Gravitational collapse thus Gravitational Collapse occurs promptly, immediately following the initial com- pression. If the total mass is large enough, the object by Steven W. Stahler breaks apart even as it is collapsing. This is the traditional picture of fragmentation, an idea invoked by several gener- ations of theorists (Hoyle 1953; Low & Lynden-Bell 1976), and now being resurrected in large-scale simulations of cluster formation (e.g., MacLow & Klessen 2004). A succinct, if rather technical, way of distinguishing the two routes is through the dynamical state of the cloud just before it collapses. A cloud evolving along the slow route passes through stable configurations in near force balance between self-gravity and pressure. The cloud may undergo oscillations as it grows (Keto et al. 2006). Just before collapse, the configuration is “marginally stable.” Its fundamental mode of oscillation has zero (or nearly zero) frequency, meaning that restoring forces act very weakly and slowly to rectify any impressed disturbance. In contrast, a cloud that collapses via the fast route is 1 Two Routes to Collapse never in equilibrium. Just before the collapse, self-gravity is stronger than the outward pressure gradient. It is this substantial force imbalance that drives both prompt col- The central process in star formation is gravitational col- lapse and fragmentation, should the latter occur. Note lapse. After so many decades of exploration by theorists, that neither scenario postulates, as the immediate pre- in studies ranging from analytical to semi-analytical to collapse states, unstable equilibria. These are configura- full-blown simulations, is there anything left to say on the tions that are in temporary force balance, but depart from subject? Yes! In the realm of low-mass stars, observations that condition immediately upon being perturbed. are now revealing the physical and chemical structure of dense cores prior to collapse. Indeed, an evolutionary se- quence of starless cores is emerging (Keto & Caselli 2008), 2 Splitting the Difference although the elapsed time for each phase is poorly known. For massive stars, the observations are much sparser, but we have at least identified the entities – infrared dark In principle, one should examine carefully the physical clouds – responsible for spawning these objects (Carey et conditions and processes in the interstellar medium to de- al. 1998). In both cases, we are now confronting an issue cide which route to collapse best describes reality. How- more subtle than collapse itself, and that is its onset. It ever, the actual course of research in this branch of as- is time to take stock of the theoretical situation. trophysics, as in any other, has not been this straightfor- ward. The very first numerical simulation of cloud col- I will focus here on low-mass star formation, and first pose lapse leading to the birth of a low-mass star was that of the broadest question of all. How does a molecular cloud Larson (1969). This pioneering work actually predated arrive at the point where it undergoes gravitational col- the discovery of molecular clouds. Lacking any empirical lapse? Quite generally, there are two possibilities, de- guide, Larson chose a collapse model and initial conditions pending on how rapidly the cloud changes prior to col- based on computational feasibility and physical plausibil- lapse. In the “slow” route, the object gradually accrues ity. The first issue constrained him to adopt a spherical mass from its environment. At first, whatever internal cloud, which he endowed with a spatially uniform temper- pressure is available (thermal, turbulent, magnetic) suc- ature. He also gave the cloud a uniform density initially. cessfully counteracts self-gravity. Thus, the cloud evolves For its starting radius, he chose the largest value that led through a sequence of equilibrium states. Eventually, it to continuing collapse, as opposed to an early bounce. gains enough mass to tip over the edge into collapse. The buildup period is, by hypothesis, long compared to the An isothermal cloud with uniform density has no inter- eventual collapse time. nal pressure gradient. Thus, Larson’s initial state was far

9 out of force balance. In this sense, he was simulating a After years of effort by several groups, the appropriate collapse that could only have been achieved via the fast transitions were found and the so-called “infall signature” route, although he certainly did not characterize his model was established (for a review, see Evans 2003). This is a this way. Rather, he selected his pre-collapse cloud to be line profile exhibiting a blueward asymmetry, often with a barely capable of collapse, just the state of affairs in a slow central, self-absorption dip. The two rightmost panels of buildup. But he also knew that, if he started with an ex- Figure 1 show profiles for dense cores containing infrared act equilibrium state, the model cloud would just sit there sources. The inward speeds matching these profiles, as on the computer. He therefore compromised, selecting an determined from a simple, two-slab model, are a few tenths initial state that was marginally prone to deep collapse, of the dense core’s sound speed. Despite the nomenclature, but still able to evolve dynamically. the infall signature is actually signifying bulk, subsonic The years subsequent to Larson’s simulation witnessed a contraction, in these and many other cases. complete transformation of the observational landscape. Key was the identification of dense cores as the sites of low-mass starbirth (Beichman et al. 1986). By every em- pirical measure, these objects are in dynamical equilibrium before they produce stars. Here, the balance is between self-gravity and a combination of thermal and magnetic pressure, with turbulence playing a measurable, but rela- tively minor role (Barranco & Goodman 1998). Larson’s original intuition was fully justified, and it would seem that the slow route to collapse is the one occurring in nature. This conclusion is reinforced once we consider al- ternate scenarios. In regions of active, low-mass star for- mation, like those in Taurus, Lupus, or Chamaeleon, there are no massive stars generating HII regions or supernova shocks to compress pre-existing gas. These considerations notwithstanding, the many collapse simulations following Larson continued to adopt a hybrid Figure 1: Line profiles of three dense cores, with the var- set of initial conditions. As one example, the influential ious molecules and transitions indicated. The leftmost study of Foster & Chevalier (1993) began with a marginally panel shows data for a starless core. while the other two stable, isothermal sphere, but with its density everywhere cores harbor infrared sources. From Myers et al (1996). enhanced to a degree that ensured collapse. Since the origin of dense cores themselves was not at issue, no one But this is not the full story. Further probing has by now attempted to justify these conditions as being the natural uncovered true supersonic motion within the deeper inte- product of earlier evolution. Indeed, they are not. It is riors of a number of cores containing stars (e.g., Gregersen more straightforward to simulate on the computer a fully et al. 1997; Belloche et al. 2002). These interior velocities dynamical, as opposed to a quasi-static, process, and only are at most a few times the ambient sound speed. How- the former route was explored. ever, there can be little doubt that higher speeds are to be found even closer to the young star, and the essential point has been established. The collapse of molecular clouds is 3 Dense Core Dynamics not just theoretical speculation, but a reality. Even as theorists collectively breathe a sigh of relief, we The most exciting development in low-mass star formation must note that the observations bring additional news of since the identification of dense cores has been the discov- a more troubling nature. First is the fact that many dense ery of their internal motion. Cores that contain very young cores without internal stars are also contracting; the left- stars do not differ in their gross properties from those still hand panel of Figure 1 is an example. What is going on? lacking them. However, if the idea of gravitational collapse A closer look at the data offers both clarification and a de- is at all correct, then the deep interiors of these objects gree of comfort. I mentioned earlier that starless cores lie must be very different indeed. This interior gas should be along an evolutionary sequence. At one end of the spec- streaming toward the star at high speed. Detecting this trum are those of the lowest density contrast, while at the motion requires spectroscopic observations, specifically of other are cores of relatively high density that seem truly molecular lines that are sufficiently optically thin to pen- poised to collapse. It is only the latter that exhibit the etrate to the central regions of the core. spectroscopic infall signature, and their inferred, interior velocity is everywhere subsonic. This is indeed comforting

10 news, although the driving force of the subsonic contrac- increasing self-gravity, however, both the core and even the tion is a matter of some debate. I shall return to that issue shock itself began to move inward supersonically. At the toward the end of this piece. instant of star formation, the interior velocity was almost The second surprise concerns the physical extent of super- entirely supersonic. Gong & Ostriker (2011) later relaxed sonic motion in dense cores containing stars. In all studies the assumption of spherical symmetry and adopted a pla- that have obtained at least a rudimentary velocity profile, nar supersonic flow, obtaining essentially the same result it is apparent that the sonic transition occurs extremely for the core evolution. close to the star. For example, Belloche et al (2002) find Observations do show clearly that gas velocity outside the this point to be less than 0.007 pc from the center of the dense core boundary is supersonic (Pineda et al. 2010). IRAM 4191 core, which has a total radius ten times larger. Perhaps, however, the velocity vectors are randomly ori- Shirley et al. (2002) have noted that, within the region of ented, and it is an inward, subsonic drift that actually free-fall collapse, the spherically averaged density should builds up the object. Walsh et al. (2006), among others, vary as r−3/2. Their submillimeter continuum mapping have presented evidence for such widespread drift from of five, nearly spherical dense cores with embedded stars spectroscopic mapping. Motivated by such considerations, reveals a steeper (r−2) profile throughout the interiors; Motahareh Mohammadpour and I recently simulated the the transition to the flatter one associated with collapse buildup and collapse of a spherical core through subsonic occurs too deep for them to detect. inflow. We gave the core a constant radius of 0.05 pc and let gas flow across this boundary at fixed density and a speed 0.2 times the sound speed of 0.2 km s−1. In this 4 Extending the Models way, we hoped to avoid pervasive, supersonic velocities prior to star formation. The observations show that the region of true supersonic collapse, as opposed to static equilibrium or subsonic con- 1.0 traction, is confined to a region just outside the star. This is troubling because all theoretical collapse simulations to ρ ρ date find pervasive and vigorous inward motion even before 0.8 c/ b=14.0 the star forms. In the calculation of Foster & Chevalier

(1993), the innermost 44 percent of the mass has super- s sonic velocity at the instant the central star first appears. 0.6 This fraction grows as the stellar mass increases.

Part of the underlying problem is the historical tendency 0.4

to treat collapse in isolation. Recently, theorists have be- Velocity v/c gun extending their models to cover the earlier evolution leading up to this event, i.e., the formation of the dense 0.2 cores themselves. Within the fast picture, I noted earlier the large-scale cluster simulations. In the usual procedure, 0.0 a box of gas is stirred up, imitating the turbulence ob- 0.0 0.2 0.4 0.6 0.8 1.0 served in the larger clouds harboring dense cores. A steady Radius r/r state is eventually reached, in which the total energy dis- b sipation rate matches the input power driving the turbu- lence. Only at this point does the simulator switch on self- Figure 2: Evolution of the velocity profile for a cloud un- gravity, and the densest substructures promptly collapse. dergoing subsonic mass accretion. The velocity and radius In their shapes and masses, these objects can resemble are displayed in units of the sound speed and the fixed real cores to a striking degree (Offner & Krumholz 2009; boundary radius, respectively. All curves are separated Schmidt et al. 2010). Similar agreement, however, has not by equal time intervals, and the final, dashed one corre- 5 been demonstrated for their internal velocity structure. sponds to a time of 3 10 yr, soon after the star forms. From Mohammadpour× & Stahler (2013). We therefore turn once more to the slow route. Within this context, are dense cores actually created by turbulent Figure 2 shows the velocity evolution in a typical run. flows? Gong & Ostriker (2009) addressed this question For most of its prestellar life, the core evolves through via direct simulation. They built up the core through a near-equilibrium states. Inevitably, however, the interior converging, supersonic flow, taken to be spherically sym- velocity becomes supersonic. The region of supersonic flow metric. At first, the core was a growing, nearly hydrostatic then spreads rapidly outward. By the time the star has structure inside a bounding accretion shock front. With built up its full mass, the sonic transition radius is almost

11 halfway to the core boundary. This result still violates the Here M and Φ are, respectively, the core’s mass and the admittedly limited observations available. total magnetic flux penetrating it. The definition in equa- tion (1) has historical roots. Nakano & Nakamura (1978) showed that a self-gravitating slab, infinite in extent and 5 Magnetic Mediation threaded vertically by a magnetic field, is supported against radially inward collapse only if λ < 1. Now the line- There is another reason to be suspicious of the theoretical of sight field is observable spectroscopically through the models. As gas rushes inward supersonically, it builds up Zeeman effect. After making a reasonable correction for the star’s mass over a period short compared to the core’s projection, it is therefore feasible to obtain both Φ and initial free-fall collapse time. This “accretion spike,” which λ. Of course, real dense cores are not infinite slabs, so we has been obtained in all spherical simulations, creates a need to be cautious when interpreting the results. much higher luminosity in the star than is observed for Crutcher (2012) has collated a large number of Zeeman low-mass, embedded sources (see the original discussion measurements, and concludes that λ 2 3 for dense in Kenyon et al. 1990). cores. This global finding means, in essence,≈ − that a typ- Vorobyov & Basu (2010) found, again through simula- ical core’s total magnetic energy is less than its thermal tions, that infalling matter can be hung up for an extended or gravitational potential energy. It does not mean that time in the star’s surrounding disk, effectively postponing magnetic forces are dynamically unimportant now or in the accretion spike. For simplicity, they modeled the en- the core’s previous history. Only the more complete evo- tire dense core as a thin sheet; we await a more complete lutionary model will tell us if the field can keep all veloc- calculation to corroborate their intriguing result. Recall ities properly subsonic until the star forms, and restrict that a typical disk radius is 100 AU, or 0.001 pc. My the spread of collapse thereafter. own feeling is that, once a substantial part of the cloud is in vigorous motion, a lot of energy will be released at References: the star, regardless of the details on such a relatively tiny Barranco, J. A. & Goodman, A. A. 1998, ApJ, 504, 207 Beichman, C. A., Myers, P. C., Emerson, J. P., Harris, S., Mathieu, scale. Something is preventing supersonic cloud motion R., Benson, P. J., & Jennings, R. E. 1986, ApJ, 307, 337 over a large volume of the dense core. Belloche, A., Andr´e, P., Despois, D., & Blinder, S. 2002, A&A, 393, 927 The obvious culprit here is the interstellar magnetic field, Carey, S. J., Clark, F. O., Egan, M. P., Price, S. D., Shipman, R. which penetrates the interiors of all cores. Within the F., & Kuchar, T. A. 1998, ApJ, 508, 721 slow picture, the core’s gravitational contraction causes Ciolek, G. M. & Mouschouvias, Y. Ch. 1995, ApJ, 454, 195 field lines to bow inward and crowd together. The re- Crutcher, R. M. 2012, ARAA, 50, 29 Evans, N. J. 2003, in Chemistry as a Diagnostic of Star Formation, sulting buildup in magnetic tension and pressure does not ed. C. L. Curry & M. Fich (Ottawa: NRC Press), p. 157 halt contraction, since gas still creeps across field lines Foster, P. N. & Chevalier, R. A. 1993, ApJ, 416, 303 in the process known as ambipolar diffusion. Ciolek & Gong, H. & Ostriker, E. 2009, ApJ, 699, 230 Gong, H. & Ostriker, E. 2011, ApJ, 729, 120 Mouschovias (1995) tracked this motion numerically, and Gregersen, E. M., Evans, N. J., Zhou, S., & Choi, M. 1997, ApJ, found drift speeds lower than the observed ones we have 484, 256 cited. Such disagreement has led some to dismiss am- Hoyle, F. 1953, ApJ, 118, 518 bipolar diffusion as a mediating influence. The simula- Kenyon, S. W., Hartmann, L. W., Strom, K. M., & Strom, S. E. 1990, AJ, 99, 869 tion, however, again modeled the cloud as a thin sheet, so Keto, E. & Caselli, P. 2008, ApJ, 683, 238 this negative conclusion is premature. In a semi-analytic, Keto, E., Broderick, A. E., Lada, C. J., & Narayan, R. 2006, ApJ, spherical calculation, Stahler & Yen (2009) showed how 652, 1366 self-gravity eventually accelerates the flow in a marginally Low, C. & Lynden-Bell, D. 1976, MNRAS, 176, 367 MacLow, M. M. & Klessen, R. S. 1994, RvMP, 76, 125 stable core to full collapse, generating along the way sub- Mohammadpour, M. & Stahler, S. W. 2013, MNRAS, 433, 3389 sonic speeds just at the level observed. This is an encour- Myers, P. C., Mardones, D., Tafalla, M., Williams, J. P., & Wilner, aging result, but their study included no magnetic forces. D. J. 1996, ApJ, 465, L133 Nakano, T. & Nakamura, T. 1978, PASJ, 30, 681 The next major step in theory will be a three-dimensional, Offner, S. S. R. & Krumholz, M. R. 2009, ApJ, 693, 914 or at least axisymmetric, model of a slowly growing, mag- Pineda, J. E., Goodman, A. A., Arce, H. G., Caselli, P., Foster, J. netized dense core. Pending this development, researchers B., Myers, P. C., & Rosolowsky, E. W. 2010, ApJ, 712, 116 Schmidt, W., Kern, S. A. W., Federrath, C., & Klessen, R. S. 2010, are already confronting the issue of magnetic support in a AA, 516, 25 less detailed, global manner that is amenable to observa- Shirley, Y. L., Evans, N. J., & Rawlings, J. M. C. 2002, ApJ, 575, tional check. Define a nondimensional quantity λ by 337 Stahler, S. W. & Yen, J. J. 2009, MNRAS, 396, 579 2 π G1/2 M Vorobyov, E. I. & Basu, S. 2010, ApJ, 719, 1896 λ = . (1) Walsh, A. J., Bourke, T. L., & Myers, P. C. 2006, ApJ, 637, 860 Φ

12 Abstracts of recently accepted papers

The B1 shock in the L1157 outflow as seen at high spatial resolution Milena Benedettini1, Serena Viti2, Claudio Codella3, Frederic Gueth4, Arturo Gomez-Ruiz3, Rafael Bachiller5, Maria T. Beltran3, Gemma Busquet1, Cecilia Ceccarelli6 and Bertrand Lefloch6 1 INAF - IAPS, Roma, Italy 2 Department of Physics and Astronomy, University College London, London, UK 3 INAF – Osservatorio Astrofisico di Arcetri, Firenze, Italy 4 Institut de Radio Astronomie Millimetrique, Saint Martin d’Heres, France 5 Observatorio Astronomico Nacional (IGN), Madrid, Spain 6 UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d’Astrophysique de Grenoble, Grenoble, France E-mail contact: milena.benedettini at inaf.it We present high spatial resolution (750 AU at 250 pc) maps of the B1 shock in the blue lobe of the L1157 outflow in four lines: CS (3–2), CH3OH (3K–2K), HC3N (16–15) and p-H2CO (202–301). The combined analysis of the morphology and spectral profiles has shown that the highest velocity gas is confined in a few compact ( 5′′) bullets while the lowest velocity gas traces the wall of the gas cavity excavated by the shock expansion. A large≈ velocity gradient model applied to the CS (3–2) and (2–1) lines provides an upper limit of 106 cm−3 to the averaged gas density in B1 and 3 5 −3 a range of 5 10 nH2 5 10 cm for the density of the high velocity bullets. The origin of the bullets is still uncertain: they× could≤ be the≤ result× of local instabilities produced by the interaction of the jet with the ambient medium or could be clump already present in the ambient medium that are excited and accelerated by the expanding outflow. The column densities of the observed species can be reproduced qualitatively by the presence in B1 of a C–type shock and only models where the gas reaches temperatures of at least 4000 K can reproduce the observed HC3N column density. Accepted by MNRAS http://arxiv.org/pdf/1309.0433v1

Fragmentation, infall, and outflow around the showcase massive protostar NGC7538 IRS1 at 500 AU resolution H. Beuther1, H. Linz1 and Th. Henning1 1 Max Planck Institute for Astronomy, K¨onigstuhl 17, 69117 Heidelberg, Germany E-mail contact: beuther at mpia.de Aims: Revealing the fragmentation, infall, and outflow processes in the immediate environment around massive young stellar objects is crucial for understanding the formation of the most massive stars. Methods: With this goal in mind we present the so far highest spatial-resolution thermal submm line and continuum observations toward the young high-mass protostar NGC7538 IRS1. Using the Plateau de Bure Interferometer in its most extended configuration at 843µm wavelength, we achieved a spatial resolution of 0′′. 2 0′′. 17, corresponding to 500AU at a distance of 2.7 kpc. × Results:∼ For the first time, we have observed the fragmentation of the dense inner core of this region with at least three subsources within the inner 3000 AU. The outflow exhibits blue- and red-shifted emission on both sides of the central source indicating that the current orientation has to be close to the line-of-sight, which differs from other recent models. We observe rotational signatures in northeast-southwest direction; however, even on scales of 500 AU, we

13 do not identify any Keplerian rotation signatures. This implies that during the early evolutionary stages any stable Keplerian inner disk has to be very small ( 500 AU). The high-energy line HCN(4–3)ν2=1 (Eu/k=1050K) is detected over an extent of approximately 3000 AU.≤ In addition to this, the detection of red-shifted absorption from this line −3 −1 toward the central dust continuum peak position allows us to estimate infall rates of 1.8 10 M⊙ yr on the smallest spatial scales. Although all that gas will not necessarily be accreted onto the central∼ × protostar, nevertheless, such inner core infall rates are among the best proxies of the actual accretion rates one can derive during the early embedded star formation phase. These data are consistent with collapse simulations and the observed high multiplicity of massive stars. Accepted by Astronomy & Astrophysics http://www.mpia.de/homes/beuther/papers.html http://arxiv.org/pdf/1309.1018

The Gemini NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group Stars Beth A. Biller1, Michael C. Liu2, Zahed Wahhaj2, Eric L. Nielsen2, Thomas L. Hayward3, Jared R. Males4, Andrew Skemer4, Laird M. Close4, Mark Chun5, Christ Ftaclas1, Fraser Clarke6, Niranjan Thatte6, Evgenya L. Shkolnik7, I. Neill Reid8, Markus Hartung3, Alan Boss9, Douglas Lin10, Silvia H.P. Alencar11, Elisabete de Gouveia Dal Pino12, Jane Gregorio-Hetem12, Douglas Toomey13 1 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69115 Heidelberg, Germany 2 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA 3 Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena, Chile 4 Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA 5 Institute for Astronomy, 640 North Aohoku Place, #209, Hilo, Hawaii 96720-2700 USA 6 Department of Astronomy, University of Oxford, DWB, Keble Road, Oxford OX1 3RH, U.K. 7 Lowell Observatory, 1400 West Mars Hill Road Flagsta, AZ 86001 8 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 9 Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Wash- ington, DC 20015, USA 10 Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA 11 Departamento de Fisica - ICEx - Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 30270-901, Belo Horizonte, MG, Brazil 12 Universidade de Sao Paulo, IAG/USP, Departamento de Astronomia, Rua do Matao, 1226, 05508-900, Sao Paulo, SP, Brazil 13 Mauna Kea Infrared, LLC, 21 Pookela St., Hilo, HI 96720, USA E-mail contact: beth.biller at gmail.com We report results of a direct imaging survey for giant planets around 80 members of the Beta Pic, TW Hya, Tucana- Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini NICI Planet-Finding Cam- ′′ paign. For this sample, we obtained median contrasts of ∆H=13.9 mag at 1 in combined CH4 narrowband ADI+SDI mode and median contrasts of ∆H=15.1 mag at 2′′ in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with NICI all other candidates that lay within 400 AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI campaign followup. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36 6 M , 16.4 1.0 AU, Biller et al. 2010), CD -35 2722B ± Jup ± (31 8 M , 67 4 AU, Wahhaj et al. 2011), HD 12894B (0.46 0.08 M⊙, 15.7 1.0 AU), and BD+07 1919C (0.20 0.03 ± Jup ± ± ± ± M⊙, 12.5 1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law mod- ± els of planet distributions and hot-start evolutionary models, we restrict the frequency of 1–20 MJup companions at semi-major axes from 10–150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. Accepted by ApJ http://arxiv.org/pdf/1309.1462

14 Infrared Spectroscopic Survey of the Quiescent Medium of Nearby Clouds: I. Ice For- mation and Grain Growth in Lupus A.C.A. Boogert1, J.E. Chiar2, C. Knez3,4, K.I. Oberg¨ 5,6, L.G. Mundy3, Y.J. Pendleton7, A.G.G.M. Tielens8, and E.F. van Dishoeck8,9 1 IPAC, NASA Herschel Science Center, Mail Code 100-22, California Institute of Technology, Pasadena, CA 91125, USA 2 SETI Institute, Carl Sagan Center, 189 Bernardo Av., Mountain View, CA 94043, USA 3 Department of Astronomy, University of Maryland, College Park, MD 20742, USA 4 Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA 5 Departments of Chemistry and Astronomy, University of Virginia, Charlottesville, VA 22904, USA 6 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 7 Solar System Exploration Research Virtual Institute, NASA Ames Research Center, Moett Field, CA 94035, USA 8 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, the Netherlands 9 Max Planck Institut f¨ur Extraterrestrische Physik (MPE), Giessenbachstr.1, 85748 Garching, Germany E-mail contact: aboogert at ipac.caltech.edu Infrared photometry and spectroscopy (1–25 µm) of background stars reddened by the Lupus molecular cloud complex are used to determine the properties of the grains and the composition of the ices before they are incorporated into circumstellar envelopes and disks. H2O ices form at extinctions of AK = 0.25 0.07 mag (AV = 2.1 0.6). Such a low ice formation threshold is consistent with the absence of nearby hot stars.± Overall, the Lupus clouds±− are in an early chemical phase. The abundance of H O ice (2.3 0.1 10−5 relative to N ) is typical for quiescent regions, but 2 ± × H lower by a factor of 3–4 compared to dense envelopes of YSOs. The low solid CH3OH abundance (<3–8% relative to H2O) indicates a low gas phase H/CO ratio, which is consistent with the observed incomplete CO freeze out. Furthermore it is found that the grains in Lupus experienced growth by coagulation. The mid-infrared (>5 µm) continuum extinction relative to AK increases as a function of AK. Most Lupus lines of sight are well fitted with empirically derived extinction curves corresponding to R 3.5(A = 0.71) and R 5.0(A =1.47). For lines of V ∼ K V ∼ K sight with AK > 1.0 mag, the τ9.7/AK ratio is a factor of 2 lower compared to the diffuse medium. Below 1.0 mag, values scatter between the dense and diffuse medium ratios. The absence of a gradual transition between diffuse and dense medium-type dust indicates that local conditions matter in the process that sets the τ9.7/AK ratio. This process is likely related to grain growth by coagulation, as traced by the A7.4/AK continuum extinction ratio, but not to ice mantle formation. Conversely, grains acquire ice mantles before the process of coagulation starts. Accepted by ApJ http://arxiv.org/pdf/1309.2999

Interplay between chemistry and dynamics in embedded protostellar disks Christian Brinch1,2 and Jes K. Jørgensen1,2 1 Niels Bohr Institute, University of Copenhagen, Denmark 2 Centre for Star and Planet Formation and Natural History Museum of Denmark, University of Copenhagen, Denmark E-mail contact: brinch at nbi.dk A fundamental part of the study of star formation is to place young stellar objects in an evolutionary sequence. Establishing a robust evolutionary classification scheme allows us not only to understand how the Sun was born but also to predict what kind of main sequence star a given protostar will become. Traditionally, low-mass young stellar objects are classified according to the shape of their spectral energy distributions. Such methods are, however, prone to misclassification due to degeneracy and do not constrain the temporal evolution. More recently, young stellar objects have been classified based on envelope, disk, and stellar masses determined from resolved images of their continuum and line emission at submillimeter wavelengths. Through detailed modeling of two Class I sources, we aim at determining accurate velocity profiles and explore the role of freeze-out chemistry in such objects. We present new Submillimeter Array observations of the continuum and HCO+ line emission at 1.1 mm toward two protostars, IRS 63 and IRS 43 in the Ophiuchus star forming region. The sources were modeled in detail using dust radiation transfer to fit the SED and continuum images and line radiation transfer to produce synthetic position-velocity diagrams. We used a χ2 search algorithm to find the best model fit to the data and to estimate the errors in the model variables.

15 Our best fit models present disk, envelope, and stellar masses, as well as the HCO+ abundance and inclination of both sources. We also identify a ring structure with a radius of about 200 AU in IRS 63. We find that freeze-out chemistry is important in IRS 63 but not for IRS 43. We show that the velocity field in IRS 43 is consistent with Keplerian rotation. Owing molecular depletion, it is not possible to draw a similar conclusion for IRS 63. We identify a ring-shaped structure in IRS 63 on the same spatial scale as the disk outer radius. No such structure is seen in IRS 43. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1309.6509

Identifying Young Stars in Massive Star-Forming Regions for the MYStIX Project Patrick S. Broos1, Konstantin V. Getman1, Matthew S. Povich1,2, Eric D. Feigelson1, Leisa K. Townsley1, Tim Naylor3, Michael A. Kuhn1, R. R. King3 and Heather A. Busk1 1 Department of Astronomy & Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802, USA 2 Department of Physics and Astronomy, California State Polytechnic University, 3801 West Temple Ave, Pomona, CA 91768, USA 3 School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK E-mail contact: patb at astro.psu.edu The Massive Young star-forming Complex Study in Infrared and X-rays (MYStIX) project requires samples of young stars that are likely members of 20 nearby Galactic massive star-forming regions. Membership is inferred from statis- tical classification of X-ray sources, from detection of a robust infrared excess that is best explained by circumstellar dust in a disk or infalling envelope, and from published spectral types that are unlikely to be found among field stars. We present the MYStIX membership lists here, and describe in detail the statistical classification of X-ray sources via a ’Naive Bayes Classifier.’ These membership lists provide the empirical foundation for later MYStIX science studies. Accepted by Astrophysical Journal Supplements (MYStIX issue) http://www.astro.psu.edu/mystix http://arXiv.org/pdf/1309.4500

The Mopra Southern Galactic Plane CO Survey Michael Burton1, Catherine Braiding1, Christian Glueck2, Paul Goldsmith3, Jarryd Hawkes4, David Hollenbach5, Craig Kulesa6, Chris Martin7, Jorge Pineda8, Gavin Rowell4, Robert Simon2, Anthony Stark9, Juergen Stutzki2, Nicholas Tothill10, James Urquhart11, Chris Walker6, Andrew Walsh12 and Mark Wolfire13 1 University of New South Wales, Australia 2 Universitat zu Koln, Germany 3 JPL, USA 4 University of Adelaide, Australia 5 SETI, USA 6 University of Arizona, USA 7 Oberlin College, USA 8 JPL, USA 9 Harvard Smithsonian Center for Astrophysics, USA 10 University of Western Sydney, Australia 11 MPIfR Bonn, Germany 12 Curtin University, Australia 13 University of Maryland, USA E-mail contact: m.burton at unsw.edu.au We present the first results from a new carbon monoxide (CO) survey of the southern Galactic plane being conducted with the Mopra radio telescope in Australia. The 12CO, 13CO and C18O J=1–0 lines are being mapped over the

16 l = 305◦ 345◦,b = 0.5◦ portion of the 4th quadrant of the Galaxy, at 35′′ spatial and 0.1 km/s spectral resolution. The survey− is being± undertaken with two principal science objectives: (i) to determine where and how molecular clouds are forming in the Galaxy and (ii) to probe the connection between molecular clouds and the “missing” gas inferred from gamma-ray observations. We describe the motivation for the survey, the instrumentation and observing techniques being applied, and the data reduction and analysis methodology. In this paper we present the data from the first degree surveyed, l = 323◦ 324◦,b = 0.5◦. We compare the data to the previous CO survey of this region and present metrics quantifying the− performance± being achieved; the rms sensitivity per 0.1 km/s velocity channel is 1.5K for 12CO and 0.7 K for the other lines. We also present some results from the region surveyed, including ∼line fluxes, column densities,∼ molecular masses, 12CO/13CO line ratios and 12CO optical depths. We also examine how these quantities vary as a function of distance from the Sun when averaged over the 1 square degree survey area. 6 Approximately 2 10 M⊙ of molecular gas is found along the G323 sightline, with an average H2 number density of n 1 cm−3 within× the Solar circle. The CO data cubes will be made publicly available as they are published. H2 ∼ Accepted by Publications of the Astronomical Society of Australia (PASA) http://www.phys.unsw.edu.au/mopraco

Massive stars in massive clusters IV: Disruption of clouds by momentum–driven winds J.E. Dale1, J. Ngoumou2, B. Ercolano1 and I.A. Bonnell3 1 Excellence Cluster ‘Universe’, Boltzmannstr. 2, 85748 Garching, Germany 2 Universitaets Sternwarte Munchen, Scheinerstr. 1, 81679 M¨unchen, Germany 3 Department of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS E-mail contact: dale.james.e at gmail.com We examine the effect of momentum–driven OB–star stellar winds on a parameter space of simulated turbulent Giant Molecular Clouds using SPH hydrodynamical simulations. By comparison with identical simulations in which ionizing radiation was included instead of winds, we show that momentum–driven winds are considerably less effective in disrupting their host clouds than are HII regions. The wind bubbles produced are smaller and generally smoother than the corresponding ionization–driven bubbles. Winds are roughly as effective in destroying the very dense gas in which the O–stars are embedded, and thus shutting down the main regions of star–forming activity in the model clouds. However, their influence falls off rapidly with distance from the sources, so they are not as good at sweeping up dense gas and triggering star formation further out in the clouds. As a result, their effect on the star formation rate and efficiency is generally more negative than that of ionization, if they exert any effect at all. Accepted by MNRAS http://arxiv.org/pdf/1309.7355

+ Nitrogen isotopic ratios in Barnard 1: a consistent study of the N2H ,NH3, CN, HCN and HNC isotopologues F. Daniel1, M. Gerin2, E. Roue3, J. Cernicharo1, N. Marcelino4, F. Lique5, D.C. Lis6, D. Teyssier7, N. Biver8, D. Bockel´ee–Morvan8 1 Departamento de Astrof´ısica, Centro de Astrobiolog´ıa, CSIC-INTA, Ctra. de Torrejon a Ajalvir km 4, 28850 Madrid, Spain 2 LERMA, UMR 8112 du CNRS, Observatoire de Paris, Ecole Normale Sup´erieure, France 3 Observatoire de Paris, LUTH UMR CNRS 8102, 5 Place Janssen, 92195 Meudon, France 4 NRAO, 520 Edgemont Road, Charlottesville, VA 22902, USA 5 LOMC-UMR 6294, CNRS-Universit´edu Havre, 25 rue Philippe Lebon, BP 540 76058 Le Havre France 6 California Institute of Technology, Cahill Center for Astronomy and Astrophysics 301-17, Pasadena, CA 91125, USA 7 European Space Astronomy Centre, ESA, PO Box 78, 28691, Villanueva de la Ca˜nada, Madrid, Spain 8 LESIA, Observatoire de Paris, CNRS, UPMC, Universit´eParis-Diderot, 5 place Jules Janssen, 92195, Meudon, France E-mail contact: danielf at cab.inta-csic.es The 15N isotopologue abundance ratio measured today in different bodies of the solar system is thought to be connected

17 to 15N-fractionation effects that would have occured in the protosolar nebula. The present study aims at putting constraints on the degree of 15N-fractionation that occurs during the prestellar phase, through observations of D, 13C 15 + and N-substituted isotopologues towards B1b. Both molecules from the nitrogen hydride family, i.e. N2H and NH3, and from the nitrile family, i.e. HCN, HNC and CN, are considered in the analysis. As a first step, we model the continuum emission in order to derive the physical structure of the cloud, i.e. gas temperature and H2 density. These parameters are subsequently used as an input in a non-local radiative transfer model to infer the radial abundances profiles of the various molecules. Our modeling shows that all the molecules are affected by depletion onto dust grains, in the region that encompasses the B1-bS and B1-bN cores. While high levels of deuterium fractionation are derived, we conclude that no fractionation occurs in the case of the nitrogen chemistry. Independently of the chemical family, the molecular abundances are consistent with 14N/15N 300, a value representative of the elemental atomic abundances of the parental gas. The inefficiency of the 15N-fractionation∼ effects in the B1b region can be linked to the relatively high gas temperature 17K which is representative of the innermost part of the cloud. Since this region shows signs of depletion onto dust∼ grains, we can not exclude the possibility that the molecules were previously enriched in 15N, earlier in the B1b history, and that such an enrichment could have been incorporated into the ice mantles. It is thus necessary to repeat this kind of study in colder sources to test such a possibility. Accepted by A&A http://arxiv.org/pdf/1309.5782

Imaging diagnostics for transitional discs M. de Juan Ovelar1, M. Min2, C. Dominik2,3, C. Thalmann2, P. Pinilla4, M. Benisty5 and T. Birnstiel6 1 Leiden Observatory, Leiden University, P.O. Box 9513, 2300RA Leiden, The Netherlands 2 Astronomical Institute Anton Pannekoek, University of Amsterdam, 1090 GE Amsterdam, The Netherlands 3 Department of Astrophysics/IMAPP, Radboud University Nijmegen, 6500 GL Nijmegen, The Netherlands 4 Institut f¨ur Theoretische Astrophysik, Universit¨at Heidelberg, Albert-Ueberle-Straße 2, 69120 Heidelberg, Germany 5 Institut de Plan´etologie et Astrophysique Grenoble, 414 rue de la Piscine, 38400 st. Martin d’Heres, France 6 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA E-mail contact: mjovelar at strw.leidenuniv.nl Transitional discs are a special type of protoplanetary discs where planet formation is thought to be taking place. These objects feature characteristic inner cavities and/or gaps of a few tens of AUs in the sub-millimitre images of the disc. This signature suggests a localised depletion of matter in the disc that could be caused by planet formation processes. However, recent observations have revealed differences in the structures imaged at different wavelengths in some of these discs. In this paper, we aim to explain these observational differences using self-consistent physical 2-D hydrodynamical and dust evolution models of such objects, assuming their morphology is indeed generated by the presence of a planet. We use these models to derive the distribution of gas and dust in a theoretical planet- hosting disc, for various planet masses and orbital separations. We then simulate observations of the emitted and scattered light from these models with VLT/SPHERE ZIMPOL, Subaru/HiCIAO, VLT/VISIR and ALMA. We do this by first computing the full resolution images of the models at different wavelengths, and then simulating the observations accounting for the characteristics of each particular instrument. The presence of the planet generates pressure bumps in the gas distribution of the disc whose characteristics strongly depend on the planet mass and position. These bumps cause large grains to accumulate while small grains are allowed into inner regions. This spatial differentiation of the grain sizes explains the differences in the observations since different wavelengths and observing techniques trace different parts of the dust size distribution. Based on this effect, we conclude that the combination of visible/near-infrared polarimetric and sub-mm images is the best strategy to constrain the properties of the unseen planet responsible for the disc structure. Accepted by A&A http://arxiv.org/pdf/1309.1039

Feedback-regulated star formation: II. dual constraints on the SFE and the age spread of stars in massive clusters Sami Dib1,2,3, Julia Gutkin4, Wolfgang Brandner3 and Shantanu Basu5

18 1 Astronomisches Rechen-Institut, Zentrum f¨ur Astronomie der Universit¨at Heidelberg, M¨onchhofstrasse 12-14 69120 Heidelberg, Germany 2 School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran 3 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69117, Heidelberg, Germany 4 UPMC-CNRS, UMR 7095, Institut d’Astrophysique de Paris, 75014, Paris, France 5 Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada E-mail contact: sami at ari.uni-heidelberg.de We show that the termination of the star formation process by winds from massive stars in protocluster forming clumps imposes dual constraints on the star formation efficiencies (SFEs) and stellar age spreads (∆τ∗) in stellar clusters. We have considered two main classes of clump models. One class of models in one in which the core formation efficiency (CFE) per unit time and as a consequence the star formation rate (SFR) is constant in time and another class of models in which the CFE per unit time, and as a consequence the SFR, increases with time. Models with an increasing mode of star formation yield shorter age spreads (a few 0.1 Myrs) and typically higher SFEs than models in which star formation is uniform in time. We find that the former models reproduce remarkably well the SFE ∆τ∗ values of starburst clusters such as NGC 3603 YC and Westerlund 1, while the latter describe better the star formation− process in lower density environments such as in the Orion Nebula Cluster. We also show that the SFE and ∆τ∗ of massive clusters are expected to be higher in low metallicity environments. This could be tested with future large extragalactic surveys of stellar clusters. We advocate that placing a stellar cluster on the SFE-∆τ∗ diagram is a powerful method to distinguish between different stellar clusters formation scenarios such as between generic gravitational instability of a gas cloud/clump or as the result of cloud-cloud collisions. It is also a very useful tool for testing star formation theories and numerical models versus the observations. Accepted by MNRAS http://arxiv.org/pdf/1306.6338

The dependence of stellar age distributions on GMC environment C. L. Dobbs1, J. E. Pringle2 and T. Naylor1 1 University of Exeter, UK 2 University of Cambridge, UK E-mail contact: dobbs at astro.ex.ac.uk In this Letter, we analyse the distributions of stellar ages in Giant Molecular Clouds (GMCs) in spiral arms, inter-arm spurs, and at large galactic radii, where the spiral arms are relatively weak. We use the results of numerical simulations of galaxies, which follow the evolution of GMCs and include star particles where star formation events occur. We find that GMCs in spiral arms tend to have predominantly young (< 10 Myr) stars. By contrast, clouds which are the remainders of spiral arm GMAs that have been sheared into inter-arm GMCs, contain fewer young (< 10 Myr) stars, and more 20 Myr stars. We also show that clouds which form in the absence of spiral arms, due to local gravitational and∼ thermal instabilities, contain preferentially young stars. We propose the age distributions of stars in GMCs will be a useful diagnostic to test different cloud evolution scenarios, the origin of spiral arms, and the success of numerical models of galactic star formation. We discuss the implications of our results in the context of Galactic and extragalactic molecular clouds. Accepted by MNRAS Letters http://arxiv.org/pdf/1309.6244

Hiding in the Shadows: Searching for Planets in Pre–transitional and Transitional Disks Jack Dobinson1,2, Zo¨eM. Leinhardt1, Sarah E. Dodson-Robinson3, and Nick A. Teanby2 1 School of Physics, H. H. Wills Physics Laboratory, University of Bristol, Bristol, BS8 1TL, UK 2 School of Earth Sciences, Wills Memorial Building, University of Bristol, Bristol, BS8 1RJ, UK 3 Astronomy Department, University of Texas at Austin, Austin, TX 78712, USA

19 E-mail contact: jack.dobinson at bristol.ac.uk Transitional and pre–transitional disks can be explained by a number of mechanisms. This work aims to find a single observationally detectable marker that would imply a planetary origin for the gap and, therefore, indirectly indicate the presence of a young planet. N-body simulations were conducted to investigate the effect of an embedded planet of one Jupiter mass on the production of instantaneous collisional dust derived from a background planetesimal disk. Our new model allows us to predict the dust distribution and resulting observable markers with greater accuracy than previous work. Dynamical influences from a planet on a circular orbit are shown to enhance dust production in the disk interior and exterior to the planet orbit while removing planetesimals from the the orbit itself creating a clearly defined gap. In the case of an eccentric planet the gap opened by the planet is not as clear as the circular case but there is a detectable asymmetry in the dust disk. Accepted by ApJL http://arxiv.org/pdf/1309.6480

Interpreting Near Infrared Hydrogen Line Ratios in T Tauri Stars Suzan Edwards1,5, John Kwan2, William Fischer3,5, Lynne Hillenbrand4, Kimberly Finn6, Kristina Fedorenko1, and Wanda Feng1 1 Five College Astronomy Department, Smith College, Northampton, MA 01063, USA 2 Five College Astronomy Department, University of Massachusetts, Amherst, MA 01003, USA 3 Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA 4 Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA 5 Visiting Astronomer, NASA Infrared Telescope Facility 6 Five College Astronomy Department, Mount Holyoke College, South Hadley, MA 01063, USA E-mail contact: sedwards at smith.edu In accreting young stars one of the prominent spectral features in the near infrared is the Paschen and Brackett series in emission. We examine hydrogen line ratios for 16 classical T Tauri stars from SpeX spectra and and assess the trends with veiling and accretion. The observed line ratios are compared to two theoretical models for line formation: (1) Baker and Menzel’s (1938) Case B for radiative ionization and recombination and (2) a set of local line excitation calculations designed to replicate the conditions in T Tauri winds and magnetic accretion columns (Kwan & Fischer 2011). While the comparison between Case B and observed line ratios implies a wide range in electron density and temperature among the hydrogen line formation regions in T Tauri stars, the predictions of the local line excitation models give consistent results across multiple diagnostics. Under the assumptions of the local line excitation 10 11 −3 calculations, we find that nH in the hydrogen line formation region is constrained to 2 10 – 2 10 cm , where stars with higher accretion rates have densities at the higher end of this range. Because× of uncertainties× in extinction, temperature is not well delineated but falls within the range expected for collisional excitation to produce the line photons. We introduce new diagnostics for assessing extinction based on near infrared hydrogen line ratios from the local line excitation calculations. Accepted by ApJ http://arxiv.org/pdf/1309.4449

A combined IRAM and Herschel/HIFI study of cyano(di)acetylene in Orion KL: ten- tative detection of DC3N G.B. Esplugues1, J. Cernicharo1, S. Viti2, J.R. Goicoechea1, B. Tercero1, N. Marcelino3, Aina Palau4, T.A. Bell1, E.A. Bergin5 , N.R. Crockett5, and S. Wang5 1 Centro de Astrobiolog´ıa(CSIC-INTA), Ctra. de Torrej´on-Ajalvir, km. 4, E-28850 Torrej´on de Ardoz, Madrid, Spain 2 Department of Physics & Astronomy, University College London, Gower St. London WC1E 6BT 3 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA 4 Institut de Ci´encies de l’Espai (CSIC-IEEC), Campus UAB-Facultat de Ci´encies, Torre C5-parell 2, E-08193 Bel- laterra, Barcelona, Spain 5 Department of Astronomy, University of Michigan, 500 Church St, Ann Arbor, MI 48109, USA

20 E-mail contact: espluguesbg at cab.inta-csic.es

We present a study of cyanoacetylene (HC3N) and cyanodiacetylene (HC5N) in Orion KL, through observations from two line surveys performed with the IRAM 30m telescope and the HIFI instrument on board the Herschel telescope. The frequency ranges covered are 80–280 GHz and 480–1906 GHz. We model the observed lines of HC3N, HC5N, their isotopologues (including DC3N), and vibrational modes, using a non-LTE radiative transfer code. To investigate the chemical origin of HC3N and DC3N in Orion KL, we use a time-dependent chemical model. We detect 40 lines of the 13 ground state of HC3N and 68 lines of its C isotopologues. We also detect 297 lines of six vibrational modes of this molecule (ν7, 2ν7, 3ν7, ν6, ν5, and ν6 + ν7) and 35 rotational lines of the ground state of HC5N. We report the first tentative detection of DC3N in a giant molecular cloud with a DC3N/HC3N abundance ratio of 0.015. We provide column densities and isotopic and molecular abundances. We also perform a 2′ 2′ map around Orion IRc2 and we × present maps of HC3N lines and maps of lines of the HC3N vibrational modes ν6 and ν7. In addition, a comparison of our results for HC3N with those in other clouds allows us to derive correlations between the column density, the FWHM, the mass, and the luminosity of the clouds. The high column densities of HC3N obtained in the hot core, make this molecule an excellent tracer of hot and dense gas. In addition, the large frequency range covered reveals the need to consider a temperature and density gradient in the hot core in order to obtain better line fits. The high D/H ratio (comparable to that obtained in cold clouds) that we derive suggests a deuterium enrichment. Our chemical models indicate that the possible deuterated HC3N present in Orion KL is formed during the gas-phase. This fact provides new hints concerning the processes leading to deuteration. Accepted by A&A http://arxiv.org/pdf/1309.0446

A Significantly Low CO Abundance Toward the TW Hya Protoplanetary Disk: A Path to Active Carbon Chemistry? C´ecile Favre1, L. Ilsedore Cleeves1, Edwin A. Bergin1, Chunhua Qi2, and Geoffrey A. Blake3 1 Department of Astronomy, University of Michigan, 500 Church St., Ann Arbor, MI 48109, USA 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 3 California Institute of Technology, Division of Geological & Planetary Sciences, MS 150-21, Pasadena, CA 91125, USA E-mail contact: cfavre at umich.edu

In this Letter we report the CO abundance relative to H2 derived toward the circumstellar disk of the T-Tauri star TW Hya from the HD (1–0) and C18O (2–1) emission lines. The HD (1–0) line was observed by the Herschel Space Observatory Photodetector Array Camera and Spectrometer whereas C18O (2–1) observations were carried out with the Submillimeter Array at a spatial resolution of 2′′. 8 1′′. 9 (corresponding to 142 97 AU). In the × × disk’s warm molecular layer (T > 20 K) we measure a disk-averaged gas-phase CO abundance relative to H2 of χ(CO) = (0.1 3) 10−5, substantially lower than the canonical value of χ(CO) = 10−4. We infer that the best explanation of− this× low χ(CO) is the chemical destruction of CO followed by rapid formation of carbon chains, or perhaps CO2, that can subsequently freeze-out, resulting in the bulk mass of carbon locked up in ice grain mantles and oxygen in water. As a consequence of this likely time-dependent carbon sink mechanism, CO may be an unreliable tracer of H2 gas mass. Accepted by ApJL http://arxiv.org/pdf/1309.5370

Probing the radial temperature structure of protoplanetary disks with Herschel/HIFI D. Fedele1, S. Bruderer1, E.F. van Dishoeck1,2, M.R. Hogerheijde2, O. Panic3, J.M. Brown4, and Th. Henning5 1 Max Planck Institut f¨ur Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany 2 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands 3 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138, USA

21 5 Max Planck Institute for Astronomy, K¨onigstuhl 17, 69117, Heidelberg, Germany E-mail contact: davide.fedele at gmail.com Herschel/HIFI spectroscopic observations of CO J=10–9, CO J=16–15 and [CII] towards HD 100546 are presented. The objective is to resolve the velocity profile of the lines to address the emitting region of the transitions and directly probe the distribution of warm gas in the disk. The spectra reveal double-peaked CO line profiles centered on the systemic velocity, consistent with a disk origin. The J=16–15 line profile is broader than that of the J=10–9 line, which in turn is broader than those of lower J transitions (6–5, 3–2, observed with APEX), thus showing a clear temperature gradient of the gas with radius. A power-law flat disk model is used to fit the CO line profiles and the CO rotational ladder simultaneously, yielding a temperature of T0 = 1100 350 K (at r0 = 13 AU) and an index of q = 0.85 0.1 for the temperature radial gradient. This indicates that the± gas has a steeper radial temperature ± gradient than the dust (mean qdust 0.5), providing further proof of the thermal decoupling of gas and dust at the disk heights where the CO lines form.∼ The [CII] line profile shows a strong single-peaked profile red-shifted by 0.5 km s−1 compared to the systemic velocity. We conclude that the bulk of the [CII] emission has a non-disk origin (e.g., remnant envelope or diffuse cloud). Accepted by ApJL http://arxiv.org/pdf/1309.2133

Probing the Radial Temperature Structure of Protoplanetary Disks with Herschel/HIFI D. Fedele1, S. Bruderer1, E.F. van Dishoeck1,2, M.R. Hogerheijde2, O. Panic3, J.M. Brown4 and Th. Henning5 1 Max Planck Institut f¨ur Extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany 2 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands 3 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138, USA 5 Max Planck Institute for Astronomy, Knigstuhl 17, D-69117 Heidelberg, Germany E-mail contact: fedele at mpe.mpg.de Herschel/HIFI spectroscopic observations of CO J = 10 9, CO J = 16 15 and [CII] toward HD 100546 are presented. The objective is to resolve the velocity profile of the lines− to address the− emitting region of the transitions and directly probe the distribution of warm gas in the disk. The spectra reveal double-peaked CO line profiles centered on the systemic velocity, consistent with a disk origin. The J = 16 15 line profile is broader than that of the J = 10 9 line, which in turn is broader than those of lower-J transitions− (6 5, 3 2, observed with APEX), thus showing− a clear temperature gradient of the gas with radius. A power-law flat−disk model− is used to fit the CO line profiles and the CO rotational ladder simultaneously, yielding a temperature of T0 = 1100 350K (at r0 = 13 AU) and an index of q = 0.85 0.1 for the temperature radial gradient. This indicates that the± gas has a steeper radial temperature ± gradient than the dust (mean qdust 0.5), providing further proof of the thermal decoupling of gas and dust at the disk heights where the CO lines form.∼ The [CII] line profile shows a strong single-peaked profile red-shifted by 0.5 km s−1 compared to the systemic velocity. We conclude that the bulk of the [CII] emission has a non-disk origin (e.g., remnant envelope or diffuse cloud). Accepted by ApJL http://arxiv.org/pdf/1309.2133

On the universality of supersonic turbulence Christoph Federrath1 1 Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, VIC 3800, Australia E-mail contact: christoph.federrath at monash.edu Compressible turbulence shapes the structure of the interstellar medium of our Galaxy and likely plays an important role also during structure formation in the early Universe. The density probability distribution function (PDF) and the power spectrum of such compressible, supersonic turbulence are the key ingredients for theories of star formation. However, both the PDF and the spectrum are still a matter of debate, because theoretical predictions are

22 limited and simulations of supersonic turbulence require enormous resolutions to capture the inertial-range scaling. Compressible turbulence shapes the structure of the interstellar medium of our Galaxy and likely plays an important role also during structure formation in the early Universe. The density probability distribution function (PDF) and the power spectrum of such compressible, supersonic turbulence are the key ingredients for theories of star formation. However, both the PDF and the spectrum are still a matter of debate, because theoretical predictions are limited and simulations of supersonic turbulence require enormous resolutions to capture the inertial-range scaling. To advance our limited knowledge of compressible turbulence, we here present and analyse the world’s largest simulations of supersonic turbulence. We compare hydrodynamic models with numerical resolutions of 2563–40963 mesh points and with two distinct driving mechanisms, solenoidal (divergence-free) driving and compressive (curl-free) driving. We find convergence of the density PDF, with compressive driving exhibiting a much wider and more intermittent density distribution than solenoidal driving by fitting to a recent theoretical model for intermittent density PDFs. Analysing the power spectrum of the turbulence, we find a pure velocity scaling close to Burgers turbulence with P (v) k−2 for both driving modes in our hydrodynamical simulations with Mach number = 17. The spectrum of the density-weighted∝ velocity ρ1/3v, however, does not provide the previously suggested universalM scaling for supersonic turbulence. We find that the power spectrum P (ρ1/3v) scales with wavenumber as k−1.74 for solenoidal driving, close to incompressible Kolmogorov turbulence (k−5/3), but is significantly steeper with k−2.10 for compressive driving. We show that this is consistent with a recent theoretical model for compressible turbulence that predicts P (ρ1/3v) k−19/9 in the presence of a strong v component as is produced by compressive driving and remains remarkably∝ constant throughout the supersonic turbulent∇ · cascade. Accepted by MNRAS http://arxiv.org/pdf/1306.3989

The Origin of Physical Variations in the Star Formation Law Christoph Federrath1 1 Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, VIC 3800, Australia E-mail contact: christoph.federrath at monash.edu Observations of external galaxies and of local star-forming clouds in the Milky Way have suggested a variety of star formation laws, i.e., simple direct relations between the column density of star formation (ΣSFR: the amount of gas forming stars per unit area and time) and the column density of available gas (Σgas). Extending previous studies, we show that these different, sometimes contradictory relations for Milky Way clouds, nearby galaxies, and high- redshift disks and starbursts can be combined in one universal star formation law in which ΣSFR is about 1% of the local gas collapse rate, Σgas/tff , but a significant scatter remains in this relation. Using computer simulations and theoretical models, we find that the observed scatter may be primarily controlled by physical variations in the Mach number of the turbulence and by differences in the star formation efficiency. Secondary variations can be induced by changes in the virial parameter, turbulent driving and magnetic field. The predictions of our models are testable with observations that constrain both the Mach number and the star formation efficiency in Milky Way clouds, external disk and starburst galaxies at low and high redshift. We also find that reduced telescope resolution does not strongly affect such measurements when ΣSFR is plotted against Σgas/tff . Accepted by MNRAS http://arxiv.org/pdf/1307.1467

Overview of the Massive Young Star-Forming Complex Study in Infrared and X-ray (MYStIX) Project Eric D. Feigelson1,2, Leisa K. Townsley1, Patrick S. Broos1, Heather A. Busk1, Konstantin V. Getman1, Robert King3, Michael A. Kuhn1, Tim Naylor3, Matthew Povich1,4, Adrian Baddeley5,6, Matthew Bate3, Remy Indebetouw7, Kevin Luhman1,2, Mark McCaughrean8, Julian Pittard9, Ralph Pudritz10, Alison Sills10, Youg Song5 and James Wadsley10 1 Department of Astronomy & Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park PA 16802, USA

23 2 Center for Exoplanets and Habitable Worlds, Penn State University, 525 Davey Laboratory, University Park PA 16802, USA 3 Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, Devon, EX4 4SB, UK 4 Department of Physics and Astronomy, California State Polytechnic University, 3801 West Temple Ave, Pomona, CA 91768, USA 5 Mathematics, Informatics and Statistics, CSIRO, Underwood Avenue, Floreat WA 6014, Australia 6 School of Mathematics and Statistics, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia 7 Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville VA 22904, USA 8 Research & Scientific Support Department, European Space Agency, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands 9 School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK 10 Department of Physics, McMaster University, 1280 Main Street West, Hamilton ON, L8S 4M1, Canada E-mail contact: edf at astro.psu.edu MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray) seeks to characterize 20 OB-dominated young clusters and their environs at distances d 4 kpc using imaging detectors on the Chandra X-ray Observatory, Spitzer Space Telescope, and the United Kingdom≤ InfraRed Telescope. The observational goals are to construct catalogs of star-forming complex stellar members with well-defined criteria, and maps of nebular gas (particularly of hot X-ray emitting plasma) and dust. A catalog of MYStIX Probable Complex Members (MPCMs) with several hundred OB stars and > 30, 000 low mass pre-main sequence is assembled. This sample and related data products will be used to seek new empirical constraints on theoretical models of cluster formation and dynamics, mass segregation, OB star formation, star formation triggering on the periphery of HII regions, the survivability of protoplanetary disks in HII regions. This paper give an introduction and overview of the project, covering the data analysis methodology and application to two star forming regions, NGC 2264 and the Trifid Nebula. Accepted by Astrophysical Journal Supplements (MYStIX issue) http://www.astro.psu.edu/mystix http://arXiv.org/pdf/1309.4483

The Environment around the Young Massive Star Cluster RSGC 1 and HESS J1837-069 Yutaka Fujita1, Hiroyuki Nakanishi2, Erik Muller3, Naoto Kobayashi4, Masao Saito3,5, Chikako Yasui4, Hiroki Kikuchi1. and Keigo Yoshinaga1 1 Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan 2 Department of Physics, Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima, Kagoshima 890-0065, Japan 3 National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan 4 Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan 5 Joint ALMA Observatory (JAO), Alonso de Cordova 3107, Vitacura, Santiago, Chile E-mail contact: fujita at vega.ess.sci.osaka-u.ac.jp We report on Mopra observations toward the young massive star cluster RSGC 1, adjoined by, and possibly associated with the gamma-ray source HESS J1837-069. We measure the CO (J=1–0) distribution around the cluster and gamma- ray source, and find that the cluster is slightly higher than the velocity ranges associated with the Crux-Scutum arm. We reveal the cluster is associated with much less molecular gas compared with other young massive clusters in the Galaxy, Westerlund 1 (Wd 1) and 2 (Wd 2), which also radiate gamma-rays. We find no other structures that would otherwise indicate the action of supernova remnants, and due to the lack of material which may form gamma-rays by hadronic interaction, we conclude that the gamma-rays detected from HESS J1837-069 are not created through proton-proton interactions, and may more plausibly originate from the pulsar that was recently found near RSGC 1. Accepted by PASJ http://arxiv.org/pdf/1309.7061

24 Local Enhancement of Surface Density in the Protoplanetary Ring Surrounding HD 142527 Misato Fukagawa1, Takashi Tsukagoshi2, Munetake Momose2, Kazuya Saigo3, Nagayoshi Ohashi4, Yoshimi Kitamura5, Shu-ichiro Inutsuka6, Takayuki Muto7, Hideko Nomura8, Taku Takeuchi9, Hiroshi Kobayashi6, Tomoyuki Hanawa10, Eiji Akiyama3, Mitsuhiko Honda11, Hideaki Fujiwara4, Akimasa Kataoka3,12, Sanemichi Z. Takahashi6,8 and Hiroshi Shibai1 1 Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan 2 College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 Japan 3 National Astronomical Observatory of Japan, 2-21-1, Osawa, Miaka, Tokyo 181-8588, Japan 4 Subaru Telescope, 650 North A’ohoku Place, Hilo, HI, 96720, USA 5 Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagami- hara 252-5210, Japan 6 Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan 7 Division of Liberal Arts, Kogakuin University, 1-24-2, Nishi-Shinjuku, Shinjuku-ku, Tokyo 163-8677, Japan 8 Department of Astronomy, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan 9 Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan 10 Center for Frontier Science, Chiba University, Inage-ku, Chiba 263-8522, Japan 11 Department of Mathematics and Physics, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan 12 School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Mitaka, 181-8588, Tokyo, Japan E-mail contact: misato at iral.ess.sci.osaka-u.ac.jp We report ALMA observations of dust continuum, 13CO J = 3–2, and C18O J = 3–2 line emission toward a gapped protoplanetary disk around HD 142527. The outer horseshoe-shaped disk shows the strong azimuthal asymmetry in dust continuum with the contrast of about 30 at 336 GHz between the northern peak and the southwestern minimum. In addition, the maximum brightness temperature of 24 K at its northern area is exceptionally high at 160 AU from a star. To evaluate the surface density in this region, the grain temperature needs to be constrained and was estimated from the optically thick 13CO J = 3–2 emission. The lower limit of the peak surface density was then calculated to be 28 g cm−2 by assuming a canonical gas-to-dust mass ratio of 100. This finding implies that the region is locally too massive to withstand self-gravity since Toomre’s Q<1–2, and thus, it may collapse into a gaseous protoplanet. Another possibility is that the gas mass is low enough to be∼ gravitationally stable and only dust grains are accumulated. In this case, lower gas-to-dust ratio by at least 1 order of magnitude is required, implying possible formation of a rocky planetary core. Accepted by PASJ http://arxiv.org/pdf/1309.7400

A kinematic study and membership analysis of the Lupus star-forming region P.A.B. Galli1, C. Bertout2, R. Teixeira1 and C. Ducourant3 1 Instituto de Astronomia, Geof´ısica e Ciˆencias Atmosf´ericas, Universidade de S˜ao Paulo, Rua do Mat˜ao, 1226 - Cidade Universit´aria, 05508-900, S˜ao Paulo - SP, Brazil 2 Institut d’Astrophysique, 98bis, Bd. Arago, 75014 Paris, France 3 Observatoire Aquitain des Sciences de l ’Univers, CNRS-UMR 5804, BP 89, Floirac, France E-mail contact: galli at astro.iag.usp.br Aims: A precise determination of the distance to individual stars is required to reliably determine the fundamental parameters (mass and age) of young stellar objects. This paper is dedicated to investigating the kinematic properties of the Lupus moving group of young stars with the primary objective of deriving individual parallaxes for each group member. Methods: We identify those stars in the Lupus star-forming region that define the comoving association of young stars by utilizing our new and improved convergent point search method that allows us to derive the precise position of the convergent point of the comoving association from the stars’ proper motions. We used published proper motion

25 catalogs and searched the literature for radial velocities, which are needed to compute individual parallaxes. We supplemented the radial velocity data with new measurements from spectroscopic observations performed with the FEROS spectrograph mounted on the MPG/ESO 2.2m telescope at La Silla. Results: We identify a comoving group with 109 pre-main sequence stars and candidates that define the kinematic properties of the Lupus low-mass star-forming region. We derive individual parallaxes for stars with known radial velocity and tentative parallaxes for the remaining group members by assuming that all stars share the same space motion. The convergent point method, combined with the k-NN algorithm, makes it possible to distinguish the Lupus and Upper Centaurus Lupus stars from the adjacent Scorpius-Centaurus association. We find significant depth effects in this region and show that the classical T Tauri stars, located in the close vicinity of the Lupus molecular clouds, form a background population, while the weak-emission line T Tauri stars are dispersed not only in angular extent but also in depth. Conclusions: The newly derived individual parallaxes will be used in a forthcoming paper to refine the masses and ages of Lupus T Tauri stars, with the aim of better constraining the lifetimes of their circumstellar, protoplanetary disks. Accepted by A&A http://arxiv.org/pdf/1309.7799

The diagnostic potential of Fe lines applied to protostellar jets T- Giannini1, B. Nisini1, S. Antoniucci1, J. M. Alcal´a2, F. Bacciotti3, R. Bonito4,5, L. Podio6, B. Stelzer4 and E. T. Whelan7 1 INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monte Porzio Catone, Italy 2 INAF-Osservatorio Astronomico di Capodimonte, via Moiariello 16, I-80131 Napoli, Italy 3 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy 4 INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy 5 Dipartimento di Fisica e Chimica, Universit´adi Palermo, Piazza del Parlamento 1, I-90134 Palermo, Italy 6 UJF-Grenoble 1 / CNRS-INSU, Institut de Planetologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Greno- ble, F-38041, France 7 Institut f¨ur Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Eberhard Karls Universit¨at, 72076 T¨ubingen, Germany E-mail contact: teresa.giannini at oa-roma.inaf.it We investigate the diagnostic capabilities of the iron lines for tracing the physical conditions of the shock-excited gas in jets driven by pre-main sequence stars. We have analyzed the 3 000-25000 A˚ , X-shooter spectra of two jets driven by the pre-main sequence stars ESO-Hα 574 and Par-Lup 3-4. Both spectra are very rich in [Fe II] lines over the whole spectral range; in addition, lines from [Fe III] are detected in the ESO-Hα 574 spectrum. NLTE codes solving the equations of the statistical equilibrium along with codes for the ionization equilibrium are used to derive the gas excitation conditions of electron temperature and density, and fractional ionization. An estimate of the iron gas-phase abundance is provided by comparing the iron lines emissivity with that of neutral oxygen at 6300 A.˚ The [Fe II] line 4 analysis indicates that the jet driven by ESO-Hα 574 is, on average, colder (Te 9000 K), less dense (ne 2 10 −3 ∼ 4 −3 ∼ cm ) and more ionized (xe 0.7) than the Par-Lup 3-4 jet (Te 13 000 K, ne 6 10 cm , xe < 0.4), even if the ∼ 5 −3 ∼ ∼ existence of a higher density component (ne 2 10 cm ) is probed by the [Fe III] and [Fe II] ultra-violet lines. The physical conditions derived from the iron lines∼ are compared with shock models suggesting that the shock at work in ESO-Hα 574 is faster and likely more energetic than the Par-Lup 3-4 shock. This latter feature is confirmed by the high percentage of gas-phase iron measured in ESO-Hα 574 (50-60% of its solar abundance in comparison with less than 30% in Par-Lup 3-4), which testifies that the ESO-Hα 574 shock is powerful enough to partially destroy the dust present inside the jet. This work demonstrates that a multiline Fe analysis can be effectively used to probe the excitation and ionization conditions of the gas in a jet without any assumption on ionic abundances. The main limitation on the diagnostics resides in the large uncertainties of the atomic data, which, however, can be overcome through a statistical approach involving many lines. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1309.5827

26 Gravitational Infall onto Molecular Filaments II. Externally Pressurized Cylinders Fabian Heitsch1 1 UNC Chapel Hill, USA E-mail contact: fheitsch at unc.edu Two aspects of the evolution of externally pressurized, hydrostatic filaments are discussed. (a) The free-fall accretion of gas onto such a filament will lead to filament parameters (specifically, FWHM–column density relations) inconsis- tent with the observations of Arzoumanian et al. (2011), except for two cases: For low-mass, isothermal filaments, agreement is found as in the analysis by Fischera & Martin (2012b). Magnetized cases, for which the field scales weakly with the density as B n1/2, also reproduce observed parameters. (b) Realistically, the filaments will be embedded not only in gas of non-zero∝ pressure, but also of non-zero density. Thus, the appearance of sheet-embedded filaments is explored. Generating a grid of filament models and comparing the resulting column density ratios and profile shapes with observations suggests that the three-dimensional filament profiles are intrinsically flatter than isothermal, beyond projection and evolution effects. Accepted by ApJ http://arxiv.org/pdf/1308.5637

The κ Andromedae System: New Constraints on the Companion Mass, System Age & Further Multiplicity Sasha Hinkley1,17, Laurent Pueyo2,18, Jacqueline K. Faherty3, Ben R. Oppenheimer4, Eric E. Mamajek5, Adam L. Kraus6, Emily Rice7,3, Michael J. Ireland8,9, Trevor David1, Lynne A. Hillenbrand1, Gautam Vasisht10, Eric Cady10, Douglas Brenner4, Aaron Veicht4, Ricky Nilsson4, Neil Zimmerman11, Ian R. Parry12, Charles Beichman13, Richard Dekany14, Jennifer E. Roberts10, Lewis C Roberts Jr.10, Christoph Baranec14, Justin R. Crepp15, Rick Burruss10, J. Kent Wallace10, David King12, Chengxing Zhai10, Thomas Lockhart10, Michael Shao10, R´emi Soummer2, Anand Sivaramakrishnan2, Louis A. Wilson16 1Department of Astronomy, Caltech, 1200 E. California Blvd, MC 249-17, Pasadena, CA 91125, USA 2STScI, 3700 San Martin Drive, Baltimore, MD 21218, USA 3Department of Astronomy, Universidad de Chile Cerro Calan, Las Condes, Chile, USA 4Astrophysics Department, AMNH, Central Park West at 79th Street, New York, NY 10024, USA 5Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171, USA 6Harvard-Smithsonian CfA, 60 Garden St, Cambridge, MA 02140, USA 7College of Staten Island, CUNY, 2800 Victory Bvld, Staten Island, NY 10314, USA 8Department of Physics and Astronomy, Macquarie University, NSW 2109, Australia 9AAO, PO Box 296, Epping NSW 1710, Australia 10JPL, 4800 Oak Grove Dr., Pasadena CA 91109, USA 11MPIA, Knigstuhl 17, 69117 Heidelberg, Germany 12Institute of Astronomy, Cambridge CB3 0HA, UK 13NExScI, California Institute of Technology, Pasadena, CA 91125 14Caltech Optical Observatories, Pasadena, CA 91125, USA 15University of Notre Dame, Dept. of Physics, 225 Nieuwland Science Hall, Notre Dame, IN 46556, USA 16Washington University, St. Louis, MO, 63130, USA 17NSF Fellow 18Sagan Fellow E-mail contact: shinkley at astro.caltech.edu κ Andromedae is a B9IVn star at 52 pc for which a faint substellar companion separated by 55 2 AU was recently announced. In this work, we present the first spectrum of the companion, “κ And B,” using the± Project 1640 high- contrast imaging platform. Comparison of our low-resolution YJH-band spectra to empirical brown dwarf spectra suggests an early-L spectral type. Fitting synthetic spectra from PHOENIX model atmospheres to our observed spectrum allows us to constrain the effective temperature to 2000 K, as well as place constraints on the companion ∼ surface gravity. Further, we use previously reported log(g) and Teff measurements of the host star to argue that the κ

27 And system has an isochronal age of 220 100 Myr, older than the 30 Myr age reported previously. This interpretation of an older age is corroborated by the photometric± properties of κ And B, which appear to be marginally inconsistent with other 10-100 Myr low-gravity L-dwarfs for the spectral type range we derive. In addition, we use Keck aperture masking interferometry combined with published radial velocity measurements to rule out the existence of any tight stellar companions to κ And A that might be responsible for the system’s overluminosity. Further, we show that luminosity enhancements due to a nearly “pole-on” viewing angle coupled with extremely rapid rotation is unlikely. κ And A is thus consistent with its slightly evolved luminosity class (IV) and we propose here that κ And, with a revised age of 220 100 Myr, is an interloper to the 30 Myr Columba association with which it was previously associated. The photometric± and spectroscopic evidence for κ And B combined with our re-assesment of the system age implies +16 a substellar companion mass of 50−13 Jupiter masses, consistent with a brown dwarf rather than a planetary mass companion. Accepted by The Astrophysical Journal. http://arxiv.org/pdf/1309.3372

A Comparative Study of Giant Molecular Clouds in M51, M33 and the Large Magellanic Cloud Annie Hughes1, Sharon Meidt1, Dario Colombo1, Eva Schinnerer1, Jerome Pety2,3, Adam Leroy4, Clare Dobbs5, Santiago Garcia-Burillo6, Todd Thompson7,8, Gaelle Dumas2, Karl Schuster2 and Carsten Kramer9 1 Max Planck Institute for Astronomy, Konigstuhl 17, D-69117 Heidelberg, Germany 2 Institut de Radioastronomie Millimetrique, 300 Rue de la Piscine, F-38406 Saint Martin d’Heres, France 3 Observatoire de Paris, 61 Avenue de l’Observatoire, F-75014 Paris, France 4 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA 5 School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK 6 Observatorio Astronomico Nacional, Observatorio de Madrid, Alfonso XII, 3, 28014 Madrid, Spain 7 Department of Astronomy, The Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, USA 8 Center for Cosmology and AstroParticle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, OH 43210, USA 9 Instituto Radioastronomia Milimetrica, Av. Divina Pastora 7, Nucleo Central, 18012 Granada, Spain E-mail contact: hughes at mpia.de We compare the properties of giant molecular clouds (GMCs) in M51 identified by the Plateau de Bure Interferometer Whirlpool Arcsecond Survey (PAWS) with GMCs identified in wide-field, high resolution surveys of CO emission in M33 and the Large Magellanic Cloud (LMC). We find that GMCs in M51 are larger, brighter and have higher velocity dispersions relative to their size than equivalent structures in M33 and the LMC. These differences imply that there are genuine variations in the average mass surface density of the different GMC populations. To explain this, we propose that the pressure in the interstellar medium surrounding the GMCs plays a role in regulating their density and velocity dispersion. We find no evidence for a correlation between size and linewidth in any of M51, M33 or the LMC when the CO emission is decomposed into GMCs, although moderately robust correlations are apparent when regions of contiguous CO emission (with no size limitation) are used. Our work demonstrates that observational bias remains an important obstacle to the identification and study of extragalactic GMC populations using CO emission, especially in molecule-rich galactic environments. Accepted by ApJ http://arxiv.org/pdf/1309.3453

Early stage massive star formation near the Galactic Center: Sgr C S. Kendrew1, A. Ginsburg2, K. Johnston1, H. Beuther1, J. Bally2, C.J. Cyganowski3, and C. Battersby2 1 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69117 Heidelberg, Germany 2 CASA, University of Colorado at Boulder, UCB 389, Boulder, CO 80309, USA 3 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA

28 E-mail contact: kendrew at mpia.de We present near-infrared spectroscopy and 1 mm line and continuum observations of a recently identified site of high mass star formation likely to be located in the Central Molecular Zone near Sgr C. Located on the outskirts of the massive evolved HII region associated with Sgr C, the area is characterized by an Extended Green Object measuring 10′′ in size (0.4 pc), whose observational characteristics suggest the presence of an embedded massive protostar driving∼ an outflow. Our data confirm that early-stage star formation is taking place on the periphery of the Sgr C HII region, with detections of two protostellar cores and several knots of H2 and Brackett γ emission alongside a 3 previously detected compact radio source. We calculate the cores’ joint mass to be 10 M⊙, with column densities of 24 −2 5 ∼ 1-2 10 cm . We show the host molecular cloud to hold 10 M⊙ of gas and dust with temperatures and column densities× favourable for massive star formation to occur, howeve∼ r, there is no evidence of star formation outside of the EGO, indicating that the cloud is predominantly quiescent. Given its mass, density, and temperature, the cloud is comparable to other remarkable non-star-forming clouds such as G0.253 in the Eastern CMZ. Accepted by ApJL http://arxiv.org/pdf/1309.0419

Three Dimensional Hydrodynamic Simulations of Multiphase Galactic Disks with Star Formation Feedback: I. Regulation of Star Formation Rates Chang-Goo Kim1, Eve C. Ostriker2 and Woong-Tae Kim3 1 Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7, Canada 2 Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA 3 Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Republic of Korea E-mail contact: cgkim at astro.princeton.edu The energy and momentum feedback from young stars has a profound impact on the interstellar medium (ISM), including heating and driving turbulence in the neutral gas that fuels future star formation. Recent theory has argued that this leads to a quasi-equilibrium self-regulated state, and for outer atomic-dominated disks results in the surface density of star formation ΣSFR varying approximately linearly with the weight of the ISM (or midplane turbulent + thermal pressure). We use three-dimensional numerical hydrodynamic simulations to test the theoretical predictions for thermal, turbulent, and vertical dynamical equilibrium, and the implied functional dependence of ΣSFR on local disk properties. Our models demonstrate that all equilibria are established rapidly, and that the expected proportionalities between mean thermal and turbulent pressures and ΣSFR apply. For outer disk regions, this results in ΣSFR Σ√ρsd, ∝ where Σ is the total gas surface density and ρsd is the midplane density of the stellar disk (plus dark matter). This scaling law arises because ρsd sets the vertical dynamical time in our models (and outer disk regions generally). The coefficient in the star formation law varies inversely with the specific energy and momentum yield from massive stars. We find proportions of warm and cold atomic gas, turbulent-to-thermal pressure, and mean velocity dispersions that are consistent with Solar-neighborhood and other outer-disk observations. This study confirms the conclusions of a previous set of simulations, which incorporated the same physics treatment but was restricted to radial-vertical slices through the ISM. Accepted by ApJ http://arxiv.org/pdf/1308.3231

Long-Term Evolution of Decaying MHD Turbulence in the Multiphase ISM Chang-Goo Kim1 and Shantanu Basu1 1 Department of Physics and Astronomy University of Western Ontario, London, Ontario N6A 3K7, Canada E-mail contact: cgkim at astro.princeton.edu Supersonic turbulence in the interstellar medium (ISM) is believed to decay rapidly within a flow crossing time irrespective of the degree of magnetization. However, this general consensus of decaying magnetohydrodynamic (MHD) turbulence relies on local isothermal simulations, which are unable to take into account the roles of global structures of magnetic fields and the ISM. Utilizing three-dimensional MHD simulations including interstellar cooling and heating,

29 we investigate decaying MHD turbulence within cold neutral medium sheets embedded in warm neutral medium. Early evolution of turbulent kinetic energy is consistent with previous results for decaying compressible MHD turbulence characterized by rapid energy decay with a power-law form of E t−1 and by short decay time compared to a flow crossing time. If initial magnetic fields are strong and perpendicular∝ to the sheet, however, long-term evolution of the kinetic energy shows that a significant amount of turbulent energy ( 0.2E0) still remains even after ten flow crossing times for models with periodic boundary conditions. The decay rate∼ is also greatly reduced as the field strength increases for such initial and boundary conditions, but not if the boundary conditions are that for a completely isolated sheet. We analyze velocity power spectra of the remaining turbulence to show that in-plane, incompressible motions parallel to the sheet dominate at later times. Accepted by ApJ http://arxiv.org/pdf/1309.4996

The MYStIX Wide-Field Near Infrared JHK Data: Optimal Photometry in Crowded Fields R. R. King1, Tim Naylor1, Patrick S. Broos2, Konstantin V. Getman2 and Eric D. Feigelson2 1 School of Physics, Stocker Road, University of Exeter, Exeter EX4 4QL, UK 2 Department of Astronomy & Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA E-mail contact: timn at astro.ex.ac.uk We present JHK infrared data from the UK Infrared Telescope for a subset of the clusters of the MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray) survey. Some of the data were obtained specifically for the MYStIX project, and some as part of the UKIRT Deep Infrared Sky Survey’s Galactic Plane Survey. In most of these fields crowding is a significant issue for aperture photometry, and so we have re-extracted the photometry from the processed images using an optimal extraction technique, and we describe how we adapt the optimal technique to mitigate the effects of crowding. Accepted by Astrophysical Journal Supplements (MYStIX issue) http://www.astro.psu.edu/mystix

A supersonic turbulence origin of Larson’s laws Alexei G. Kritsuk1, Christoph T. Lee1, and Michael L. Norman1,2 1 Physics Department and CASS, University of California, San Diego; 9500 Giman Drive, La Jolla, CA 92093-0424, USA 2 San Diego Supercomputer Center, University of California, San Diego; 10100 Hopkins Drive, La Jolla, CA 92093- 0505, USA E-mail contact: akritsuk at ucsd.edu We revisit the origin of Larson’s scaling laws describing the structure and kinematics of molecular clouds. Our analysis is based on recent observational measurements and data from a suite of six simulations of the interstellar medium, including effects of self-gravity, turbulence, magnetic field, and multiphase thermodynamics. Simulations of isothermal supersonic turbulence reproduce observed slopes in linewidth-size and mass-size relations. Whether or not self-gravity is included, the linewidth-size relation remains the same. The mass-size relation, instead, substantially flattens below the sonic scale, as prestellar cores start to form. Our multiphase models with magnetic field and domain size 200 pc reproduce both scaling and normalization of the first Larson’s law. The simulations support a turbulent interpretation of Larson’s relations. This interpretation implies that: (i) the slopes of linewidth-size and mass-size correlations are determined by the inertial cascade; (ii) none of the three Larson’s laws is fundamental; (iii) instead, if one is known, the other two follow from scale invariance of the kinetic energy transfer rate. It does not imply that gravity is dynamically unimportant. The self-similarity of structure established by the turbulence breaks in star-forming clouds due to the development of gravitational instability in the vicinity of the sonic scale. The instability leads to the formation of prestellar cores with the characteristic mass set by the sonic scale. The high-end slope of the core mass function predicted by the scaling relations is consistent with the Salpeter power-law index.

30 Accepted by MNRAS http://arxiv.org/pdf/1309.5926

A Massive Young Star-Forming Complex Study in Infrared and X-ray: X-ray Sources in Ten Star Forming Regions Michael A. Kuhn1, Konstantin V. Getman1, Patrick S. Broos1, Leisa K. Townsley1 and Eric D. Feigelson1 1 Dept. of Astronomy & Astrophysics, Pennsylvania State University, University Park PA 16802, USA E-mail contact: mkuhn1 at astro.psu.edu The Massive Young star-forming complex Study in Infrared and X-ray (MYStIX) uses data from the Chandra X-ray Observatory to identify and characterize the young stellar populations in twenty Galactic (d < 4 kpc) massive star- forming regions. Here, the X-ray analysis for Chandra ACIS-I observations of ten of the MYStIX fields is described, and a catalog of >10,000 X-ray sources is presented. In comparison to other published Chandra source lists for the same regions, the number of MYStIX detected faint X-ray sources in a region is often doubled. While the higher catalog sensitivity increases the chance of false detections, it also increases the number of matches to infrared stars. X-ray emitting contaminants include foreground stars, background stars, and extragalactic sources. The X-ray properties of sources in these classes are discussed. Accepted by Astrophysical Journal Supplements (MYStIX issue) http://www.astro.psu.edu/mystix

Massive Young Star-Forming Study in Infrared and X-rays: Mid-Infrared Observations and Catalogs Michael A. Kuhn1, Matthew S. Povich1,2, Kevin L. Luhman1,3, Konstantin V. Getman1, Heather S. Busk1 and Eric D. Felgelson1,3 1 Department of Astronomy & Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA 2 Department of Physics and Astronomy, California State Polytechnic University, Pomona, California, 91768, USA 3 Center for Exoplanets and Habitable Worlds, Pennsylvania State University, University Park PA 16802, USA E-mail contact: mkuhn1 at astro.psu.edu Spitzer IRAC observations and stellar photometric catalogs are presented for the Massive Young Star-Forming Com- plex Study in the Infrared and X-ray (MYStIX). MYStIX is a multiwavelength census of young stellar members of twenty nearby (d < 4 kpc), Galactic, star-forming regions that contain at least one O star. All regions have data available from the Spitzer Space Telescope, consisting of GLIMPSE or other published catalogs for eleven regions and results of our own photometric analysis of archival data for the remaining nine regions. This paper seeks to construct deep and reliable catalogs of sources from the Spitzer images. Mid-infrared study of these regions faces challenges of crowding and high nebulosity. Our new catalogs typically contain fainter sources than existing Spitzer studies, which improves the match rate to Chandra X-ray sources that are likely to be young stars, but increases the possibility of spurious point-source detections, especially peaks in the nebulosity. IRAC color-color diagrams help distinguish spurious detections of nebular PAH emission from the infrared excess associated with dusty disks around young stars. The distributions of sources on the mid-infrared color-magnitude and color-color diagrams reflect differences between MYStIX regions, including astrophysical effects such as stellar ages and disk evolution. Accepted by Astrophysical Journal Supplements (MYStIX issue) http://www.astro.psu.edu/mystix

Schmidt’s Conjecture and Star Formation in Molecular Clouds Charles J. Lada1, Marco Lombardi2, Carlos Roman-Zuniga3, Jan Forbrich4, and Jo˜ao F. Alves4 1 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street Cambridge, MA 02138, USA

31 2 University of Milan, Department of Physics, via Celoria 16, I-20133 Milan, Italy 3 Instituto de Astronom´ıa, Universidad Nacional Aut´onoma de M´exico, Ensenada, Ensenada BC 22860, Mexico 4 Institute for Astronomy, University of Vienna, T¨urkenschanzstrasse 17, 1180 Vienna, Austria E-mail contact: clada at cfa.harvard.edu We investigate Schmidt’s conjecture (i.e., that the star formation rate scales in a power-law fashion with the gas density) for four well-studied local molecular clouds (GMCs). Using the Bayesian methodology we show that a local β −2 Schmidt scaling relation of the form Σ∗(AK)= κAK (protostars pc ) exists within (but not between) GMCs. Further we find that the Schmidt scaling law, by itself, does not provide an adequate description of star formation activity in GMCs. Because the total number of protostars produced by a cloud is given by the product of Σ∗(AK) and ′ S (> AK), the differential surface area distribution function, integrated over the entire cloud, the cloud’s structure plays a fundamental role in setting the level of its star formation activity. For clouds with similar functional forms of ′ Σ∗(AK), observed differences in their total SFRs are primarily due to the differences in S (> AK) between the clouds. ′ The coupling of Σ∗(AK) with the measured S (> AK) in these clouds also produces a steep jump in the SFR and protostellar production above AK 0.8 magnitudes. Finally, we show that there is no global Schmidt law that relates the star formation rate and gas mass∼ surface densities between GMCs. Consequently, the observed Kennicutt-Schmidt scaling relation for disk galaxies is likely an artifact of unresolved measurements of GMCs and not a result of any underlying physical law of star formation characterizing the molecular gas. Accepted by ApJ http://arxiv.org/pdf/1309.7055

Collapse of Turbulent Cores and Reconnection Diffusion M. R. M. Le˜ao1,2, E. M. de Gouveia Dal Pino1, R. Santos-Lima1 and A. Lazarian3 1 Instituto de Astronomia, Geof´ısica e Ciˆencias Atmosf´ericas, Universidade de S˜ao Paulo, R. do Mat˜ao, 1226, S˜ao Paulo, SP 05508-090, Brazil 2 Instituto de Matem´atica, Estat´ıstica e Computa¸c˜ao Cient´ıfica, Universidade Estadual de Campinas, Campinas, SP 13083-859, Brazil 3 Department of Astronomy, University of Wisconsin, Madison, WI 53706, USA E-mail contact: mleao at ime.unicamp.br For a molecular cloud clump to form stars some transport of magnetic flux is required from the denser, internal regions to the outer regions, otherwise this can prevent the gravitational collapse. Fast magnetic reconnection which takes place in the presence of turbulence can induce a process of reconnection diffusion that has been elaborated in earlier theoretical work. We have named this process turbulent reconnection diffusion, or simply RD. This paper continues our numerical study of this process and its implications. In particular, extending our studies of reconnection diffusion in cylindrical clouds we consider more realistic clouds with spherical gravitational potentials (from embedded stars) and also account for the effects of the gas self-gravity. We demonstrate that within our setup reconnection diffusion is efficient. We have also identified the conditions under which reconnection diffusion becomes strong enough to make an initially subcritical cloud clump supercritical and induce its collapse. Our results indicate that the formation of a supercritical core is regulated by a complex interplay between gravity, self-gravity, the magnetic field strength and nearly transonic and trans-Alfv´enic turbulence and therefore, is very sensitive to the initial conditions of the system. In particular, self-gravity helps reconnection diffusion and, as a result, the magnetic field decoupling from the collapsing gas becomes more efficient compared to the case of an external gravitational field. Our simulations confirm that reconnection diffusion can transport magnetic flux from the core of collapsing clumps to the envelope, but only a few of them become nearly critical or supercritical, sub-Alfv´enic cores, which is consistent with the observations. Besides, we have found that the supercritical cores built up in our simulations develop a predominantly helical magnetic field geometry which is also consistent with recent observations. Finally, we have also evaluated the effective values of the turbulent reconnection diffusion coefficient in our simulations and found that they are much larger than the numerical diffusion, especially for initially trans-Alfv´enic clouds, thus ensuring that the detected magnetic flux removal is due to the action of the turbulent reconnection diffusion rather than to numerical diffusivity. Accepted by Astrophysical Journal http://arxiv.org/pdf/1209.1846

32 L1448-MM observations by the Herschel Key program, “Dust, Ice, and Gas In Time” (DIGIT) Jinhee Lee1, Jeong-Eun Lee1, Seokho Lee2, Joel. D. Green3, Neal J. Evans II3, Minho Choi4, Lars Kristensen5, Odysseas Dionatos6, Jes K. Jørgensen6, and the DIGIT team 1 Department of Astronomy and Space Science, Kyung Hee University, Yongin-shi, Kyungki-do 449-701, Korea 2 Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742, Korea 3 Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712-1205, USA 4 Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Yuseong, Daejeon 305-348, Korea 5 Harvard-Smithsonian Center for Astrophysics, MS78, Cambridge, MA02138, USA 6 Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5 - 7, 1350, Copenhagen, Denmark E-mail contact: jeongeun.lee at khu.ac.kr We present Herschel/PACS observations of L1448-MM, a Class 0 protostar with a prominent outflow. Numerous emission lines are detected at 55 <λ< 210 µm including CO, OH, H2O, and [O I]. We investigate the spatial distribution of each transition to find that lines from low energy levels tend to distribute along the outflow direction while lines from high energy levels peak at the central spatial pixel. Spatial maps reveal that OH emission lines are formed in a relatively small area, while [O I] emission is extended. According to the rotational diagram analysis, the CO emission can be fitted by two (warm and hot) temperature components. For H2O, the ortho-to-para ratio is close to 3. The non-LTE LVG calculations suggest that CO and H2O lines could instead be formed in a high kinetic temperature (T > 1000 K) environment, indicative of a shock origin. For OH, IR-pumping processes play an important role in the level population. The molecular emission in L1448-MM is better explained with a C-shock model, but the atomic emission of PACS [O I] and Spitzer/IRS [Si II] emission is not consistent with C-shocks, suggesting multiple shocks in this region. Water is the major line coolant of L1448-MM in the PACS wavelength range, and the best-fit LVG models predict that H2O and CO emit (50–80)% of their line luminosity in the PACS wavelength range. Accepted by ApJS http://arxiv.org/pdf/1309.2182

The state of globular clusters at birth: emergence from the gas-embedded phase Nathan Leigh1, Mirek Giersz2, Jeremy Webb3, Arkadiusz Hypki2, Guido De Marchi1, Pavel Kroupa4, and Alison Sills3 1 European Space Agency, Space Science Department, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands 2 Nicolaus Copernicus Astronomical Centre, Polish Academy of Sciences, ul. Bartycka 18, 00-716 Warsaw, Poland 3 McMaster University, Department of Physics and Astronomy, 1280 Main St. W., Hamilton, Ontario, Canada, L8S 4M1 4 Argelander Institute for Astronomy, University of Bonn, Auf dem Hugel 71, D-53121 Bonn, Germany E-mail contact: nleigh at rssd.esa.int In this paper, we discuss the origin of the observed correlation between cluster concentration c and present-day mass function (PDMF) slope α reported by De Marchi, Paresce & Pulone. This relation can either be reproduced from universal initial conditions combined with some dynamical mechanism(s) that alter(s) the cluster structure and mass function over time, or it must arise early on in the cluster lifetime, such as during the gas-embedded phase of cluster formation. Using a combination of Monte Carlo and N-body models for globular cluster evolution performed with the MOCCA and NBODY6 codes, respectively, we explore a number of dynamical mechanisms that could affect the observed relation. For the range of initial conditions considered here, our results are consistent with an universal initial binary fraction 10% (which does not, however, preclude 100%) and an universal initial stellar mass function resembling the standard≈ Kroupa distribution. Most of the dispersion observed in the c-α relation can be attributed to two-body relaxation and Galactic tides. However, dynamical processes alone could not have reproduced the dispersion in concentration, and we require at least some correlation between the initial concentration and the total cluster mass. We argue that the origin of this trend could be connected to the gas-embedded phase of cluster evolution. Accepted by MNRAS http://arxiv.org/pdf/1309.7054

33 The binary fractions in the massive young Large Magellanic Cloud star clusters NGC 1805 and NGC 1818 Chengyuan Li1,2,3, Richard de Grijs1,2and Licai Deng3 1 Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871, China 2 Department of Astronomy, Peking University, Yi He Yuan Lu 5, Hai Dian District, Beijing 100871, China 3 Key Laboratory for Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China E-mail contact: joshuali at pku.edu.cn Using high-resolution data sets obtained with the Hubble Space Telescope, we investigate the radial distributions of the F-type main-sequence binary fractions in the massive young Large Magellanic Cloud star clusters NGC 1805 and NGC 1818. We apply both an isochrone-fitting approach and χ2 minimization using Monte Carlo simulations, for different mass-ratio cut-offs, q, and present a detailed comparison of the methods’ performance. Both methods yield the same radial binary fraction profile for the same cluster, which therefore supports the robustness and applicability of either method to young star clusters which are as yet unaffected by the presence of multiple stellar populations. The binary fractions in these two clusters are characterized by opposite trends in their radial profiles. NGC 1805 exhibits a decreasing trend with increasing radius in the central region, followed by a slow increase to the field’s binary-fraction level, while NGC 1818 shows a monotonically increasing trend. This may indicate dominance of a more complicated physical mechanism in the cluster’s central region than expected a priori. Time-scale arguments imply that early dynamical mass segregation should be very efficient and, hence, likely dominates the dynamical processes in the core of NGC 1805. Meanwhile, in NGC 1818 the behavior in the core is probably dominated by disruption of soft binary systems. We speculate that this may be owing to the higher velocity dispersion in the NGC 1818 core, which creates an environment in which the efficiency of binary disruption is high compared with that in the NGC 1805 core. Accepted by MNRAS http://arxiv.org/pdf/1309.0929

Turbulent entrainment origin of protostellar outflows Guang-Xing Li1, Keping Qiu2, Friedrich Wyrowski1 and Karl Menten1 1 Max-Planck Institut fr Radioastronomie, Auf dem Hgel, 69, 53121 Bonn, Germany 2 School of Astronomy and Space Science, Nanjing University, Nanjing 210093, China E-mail contact: gxli at mpifr-bonn.mpg.de Protostellar outflow is a prominent process that accompanies the formation of stars. It is generally agreed that wide- angled protostellar outflows come from the interaction between the wind from a forming star and the ambient gas. However, it is still unclear how the interaction takes place. In this work, we theoretically investigate the possibility that the outflow results from interaction between the wind and the ambient gas in the form of turbulent entrainment. In contrast to the previous models, turbulent motion of the ambient gas around the protostar is taken into account. In our model, the ram-pressure of the wind balances the turbulent ram-pressure of the ambient gas, and the outflow consists of the ambient gas entrained by the wind. The calculated outflow from our modelling exhibits a conical shape. The total mass of the outflow is determined by the turbulent velocity of the envelope as well as the outflow age, and the velocity of the outflow is several times higher than the velocity dispersion of the ambient gas. The outflow opening angle increases with the strength of the wind and decreases with the increasing ambient gas turbulence. The outflow exhibits a broad line width at every position. We propose that the turbulent entrainment process, which happens ubiquitously in nature, plays a universal role in shaping protostellar outflows. Accepted by A&A http://arxiv.org/pdf/1309.2294v1.pdf

Uniform infall towards the cometary Hii region in G34.26+0.15 complex? Tie Liu1, Yuefang Wu1, and Huawei Zhang1

34 1 Department of Astronomy, Peking University, 100871, Beijing China E-mail contact: liutiepku at gmail.com Gas accretion is a key process in star formation. However, the gas infall detections in high-mass star forming regions with high-spatial resolution observations are rare. Here we report the detection of gas infall towards a cometary ultracompact Hii region ”C” in G34.26+0.15 complex. The hot core associated with ”C” has a mass of 76 M⊙ and a volume density of 1.1 108 cm−3. The HCN (3–2), HCO+ (1–0) lines observed by single-dishes and the∼ CN (2–1) lines observed by the SMA× show redshifted absorption features, indicating gas infall. We found a linear relationship between the line width and optical depth of the CN (2–1) lines. Those transitions with larger optical depth and line width have larger absorption area. However, the infall velocities measured from different lines seem to be constant, indicating the gas infall is uniform. We also investigated the evolution of gas infall in high-mass star forming regions. −1 −4 −1 At stages prior to hot core phase, the typical infall velocity and mass infall rate are 1kms and 10 M⊙ yr , respectively. While in more evolved regions, the infall velocity and mass infall rates can∼ reach as high∼ as serval km· s−1 −3 −2 −1 and 10 10 M⊙ yr , respectively. Accelerated infall has been detected towards some hypercompact Hii and ultracompact∼ − Hii regions.· However, the acceleration phenomenon becomes inapparent in more evolved ultracompact Hii regions (e.g. G34.26+0.15). Accepted by ApJ http://arxiv.org/pdf/1309.6365

The Galactic Census of High- and Medium-mass Protostars. II. Luminosities and Evo- lutionary States of a Complete Sample of Dense Gas Clumps Bo Ma1, Jonathan C. Tan1,2 and Peter J. Barnes1 1 Department of Astronomy, University of Florida, Gainesville, FL, 32611, USA 2 Departments of Physics, University of Florida, Gainesville, FL 32611, USA E-mail contact: boma at astro.ufl.edu The Census of High- and Medium-mass Protostars (CHaMP) is the first large-scale (280◦ parsec-scale− resolution using mm-wave through near-IR line and continuum emission. Barnes et al. (2011) presented the source catalog of 300 dense molecular clumps from their Mopra (ATNF) HCO+(1-0) maps. Here we use archival Spitzer, MSX, IRAS∼ and mm continuum data to construct the spectral energy distributions (SEDs) of these clumps. We fit two-temperature grey-body models to the SEDs and use these to derive bolometric fluxes and, given the adopted clump distances, bolometric luminosities, L. We also consider the temperatures, Tc, of the colder component of the model fit as an approximate measure of the mean dust temperature in the clump. We evaluate the ratio, L/M, where M is the + 6.5 3 mass derived from HCO (1-0) emission. We find the clumps have 10 < L/L⊙ < 10 and 0.1 < L/M/[L⊙/M⊙] < 10 . These values are consistent with theoretical expectations of a clump population that spans a range of instantaneous star formation efficiencies from 0 to 50%. We thus expect L/M to be a good (i.e. strongly varying) evolutionary indicator of the star cluster formation∼ process. We find significant correlations of the ratio of warm to cold component flux and of the cold component temperature with L/M. We also find a near linear relation between Spitzer-IRAC specific intensity (surface brightness) and L/M, and so we propose its use as an empirical star formation efficiency indicator. The lower bound of the distribution of L/M of the clumps suggests the star formation efficiency per free- fall time is ǫff < 0.2. We do not find strong correlations of L/M with mass surface density, velocity dispersion or virial parameter. Similar to previous studies, we find a linear relation between L and dense gas mass as measured by + HCO (1-0) line luminosity, LHCO+(1−0), although there is a large scatter for any given individual clump. The sensitive nature of the CHaMP survey allows us to explore this relation down to much lower luminosity sources, 30 L⊙, than has been done before. Fitting together with extragalactic systems, the linear relation still holds, extending∼ over about 10 orders of magnitude in luminosity. The complete nature of the CHaMP survey over a several kiloparsec extent in the Milky Way also allows us to derive a measurement at an intermediate scale that bridges those of individual clumps and whole galaxies. Accepted by ApJ

35 Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N J. Malinen1, M. Juvela1, V.-M. Pelkonen2,1 and M.G. Rawlings3 1 Department of Physics, University of Helsinki, Finland 2 Finnish Centre for Astronomy with ESO, University of Turku, Finland 3 National Radio Astronomy Observatory, Charlottesville, USA E-mail contact: johanna.malinen at helsinki.fi Mapping of the near-infrared scattered light is a recent method for the study of interstellar clouds, complementing other, more commonly used methods, like dust emission and extinction. Our goal is to study the usability of this method on larger scale, and compare the properties of a filamentary structure using infrared scattering and other methods. We also study the radiation field and differences in grain emissivity between diffuse and dense areas. We have used scattered near-infrared (NIR) J, H, and K band surface brightness observations with WFCAM instrument to map a filament TMC-1N in Taurus Molecular Cloud, covering an area of 1◦ 1◦ corresponding to (2.44 pc)2. We have converted the data into an optical depth map and compared the results× with NIR extinction and∼ Herschel observations of sub-mm dust emission. We have also modelled the filament with 3D radiative transfer calculations of scattered light. We see the filament in scattered light in all three NIR bands. We note that our WFCAM observations in TMC-1N show notably lower intensity than previous results in Corona Australis using the same method. We show that 3D radiative transfer simulations predict similar scattered surface brightness levels as seen in the observations. However, changing the assumptions about the background can change the results of simulations notably. We derive emissivity, the ratio of FIR dust emission to column density, by using optical depth in the J band, τJ , obtained from Nicer NIR extinction map as an independent tracer of column density. We obtain a value 0.0013 for the ratio τ250/τJ . −25 2 This leads to opacity or dust emission cross-section σe(250µm) values 1.7 2.4 10 cm /H, depending on assumptions of the extinction curve, which can change the results by over 40%. These− × values are twice as high as obtained for diffuse areas, at the lower limit of earlier results for denser areas. We show that NIR scattering can be a valuable tool in making high resolution maps. We conclude, however, that NIR scattering observations can be complicated, as the data can show comparatively low-level artefacts. This suggests caution when planning and interpreting the observations. Accepted by A&A http://www.aanda.org/articles/aa/pdf/forth/aa21990-13.pdf

W40 region in the Gould Belt : An embedded cluster and H ii region at the junction of filaments K. K. Mallick1, M. S. N. Kumar2, D. K. Ojha1, Rafael Bachiller3, M. R. Samal4 and L. Pirogov5 1 Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India 2 Centro de Astrof´ısica da Universidade do Porto, Rua das Estrelas, 4150-762 s/n Porto, Portugal 3 Observatorio Astronmico Nacional (IGN), Alfonso XII 3, 28014, Madrid, Spain 4 Aix Marseille Universit´e, CNRS, LAM (Laboratoire d’Astrophysique de Marseille), UMR 7326, 13388 Marseille, France 5 Institute of Applied Physics, Russian Academy of Sciences, 46 Uljanov str., Nizhny Novgorod 603950, Russia E-mail contact: kshitiz at tifr.res.in We present a multiwavelength study of the W40 star-forming region using infrared (IR) observations in UKIRT JHK bands, Spitzer IRAC bands, and Herschel PACS bands; 2.12 µm H2 narrow-band imaging; and radio continuum observations from GMRT (610 and 1280 MHz), in a field of view (FoV) of 34 arcmin 40 arcmin. Archival Spitzer observations in conjunction with near-IR (NIR) observations are used∼ to identify 1162× ClassII/III and 40 Class I sources in the FoV. The nearest-neighbour stellar surface density analysis shows that majority of these young stellar objects (YSOs) constitute the embedded cluster centered on the high-mass source IRS 1A South. Some YSOs, predominantly younger population, are distributed along and trace the filamentary structures at lower stellar surface density. The cluster radius is obtained as 0.44 pc - matching well with the extent of radio emission - with a peak density of 650pc−2. The JHK data is used to map the extinction in the region which is subsequently used to compute the cloud mass. It has resulted in 126M⊙ and 71 M⊙ for the central cluster and the northern IRS5 region, respectively.

36 H2 narrow-band imaging displays significant emission, which prominently resembles fluorescent emission arising at the borders of dense regions. Radio continuum analysis shows this region as having blister morphology, with the radio peak coinciding with a protostellar source. Free-free emission spectral energy distribution (SED) analysis is used to obtain physical parameters of the overall photoionized region and the IRS 5 sub-region. This multiwavelength scenario is suggestive of star formation having resulted from merging of multiple filaments to form a hub. Star formation seems to have taken place in two successive epochs, with the first epoch traced by the central cluster and the high-mass star(s) - followed by a second epoch which is spreading into the filaments as uncovered by the Class I sources and even younger protostellar sources along the filaments. The IRS 5 H ii region displays indications of swept-up material which has possibly led to the formation of protostars. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1309.7127

Chemical modeling of the L1498 and L1517B prestellar cores: CO and HCO+ depletion S. Maret1, E.A. Bergin2 and M. Tafalla3 1 UJF-Grenoble 1 / CNRS-INSU, Institut de Plantologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041, France 2 Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor MI-48104, USA 3 Observatorio Astronmico Nacional, Alfonso XII 3, 28014 Madrid, Spain E-mail contact: sebastien.maret at obs.ujf-grenoble.fr Prestellar cores exhibit a strong chemical differentiation, which is mainly caused by the freeze-out of molecules onto the grain surfaces. Understanding this chemical structure is important, because molecular lines are often used as probes to constrain the core physical properties. Here we present new observations and analysis of the C18O (1-0) and H13CO+ (1-0) line emission in the L1498 and L1517B prestellar cores, located in the Taurus-Auriga molecular complex. We model these observations with a detailed chemistry network coupled to a radiative transfer code. Our model successfully reproduces the observed C18O (1-0) emission for a chemical age of a few 105 years. On the other hand, the observed H13CO+ (1-0) is reproduced only if cosmic-ray desorption by secondary photons is included, and if the grains have grown to a bigger size than average ISM grains in the core interior. This grain growth is consistent with the infrared scattered light (”coreshine”) detected in these two objects, and is found to increase the CO abundance in the core interior by about a factor four. According to our model, CO is depleted by about 2-3 orders of magnitude in the core center. Accepted by A&A http://arxiv.org/pdf/1309.4988

Newly identified YSO candidates towards the LDN 1188 G. Marton1, E. Vereb´elyi1, Cs. Kiss1, and J. Smidla2 1 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Konkoly Thege 15-17, H-1121 Budapest, Hungary 2 Department of Computer Science and Systems Technology, University of Pannonia, Egyetem u. 10, H-8200 Veszpr´em, Hungary E-mail contact: marton.gabor at csfk.mta.hu We present an analysis of Young Stellar Object (YSO) candidates towards the LDN 1188 molecular cloud. The YSO candidates were selected from the WISE all-sky catalogue, based on a statistical method. We found 601 candidates in the region, and classified them as Class I, Flat and Class II YSOs. Groups were identified and described with the Minimal Spanning Tree (MST) method. Previously identified molecular cores show evidence of ongoing star formation at different stages throughout the cloud complex. Accepted by Astronomische Nachrichten http://arxiv.org/pdf/1309.3299

37 A resolved debris disk around the candidate planet-hosting star HD95086 A. Mo´or1, P. Abrah´am´ 1, A.´ K´osp´al2, Gy. M. Szab´o1,3,4, D. Apai5, Z. Balog6, T. Csengeri7, C. Grady8,9, Th. Henning6, A. Juh´asz10, Cs. Kiss1, I. Pascucci5, J. Szul´agyi11 and R. Vavrek12 1 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, PO Box 67, H-1525 Budapest, Hungary 2 European Space Agency (ESA/ESTEC, SRE-SA), P.O. Box 299, 2200 AG, Noordwijk, The Netherlands 3 ELTE Gothard Astrophysical Observatory, Szent Imre hercegut ´ 112, H-9700 Szombathely, Hungary 4 Department of Experimental Physics and Astronomical Observatory, 6720 Szeged D´om t´er 9., Hungary 5 Department of Astronomy and Department of Planetary Sciences, The University of Arizona, Tucson, AZ 85721, USA 6 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69117 Heidelberg, Germany 7 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, 53121 Bonn, Germany 8 NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771, USA 9 Eureka Scientific, 2452 Delmer Street, Suite 100, Oakland, CA 94602, USA 10 Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden, The Netherlands 11 Universit´ede Nice Sophia-Antipolis, Observatoire de la Cˆote d’Azur, CNRS UMR 7293, 06108, Nice Cedex 2, France 12 Herschel Science Centre, ESA/ESAC, PO Box 78, Villanueva de la Ca˜nada, 28691, Madrid, Spain E-mail contact: moor at konkoly.hu Recently, a new planet candidate was discovered on direct images around the young (10-17 Myr) A-type star HD 95086. The strong infrared excess of the system indicates that, similarly to HR 8799, β Pic, and Fomalhaut, the star harbors a circumstellar disk. Aiming to study the structure and gas content of the HD 95086 disk, and to investigate its possible interaction with the newly discovered planet, here we present new optical, infrared and millimeter observations. We detected no CO emission, excluding the possibility of an evolved gaseous primordial disk. Simple blackbody modeling of the spectral energy distribution suggests the presence of two spatially separate dust belts at radial distances of 6 and 64 AU. Our resolved images obtained with the Herschel Space Observatory reveal a characteristic disk size of 6′′. 0 5′′. 4 (540 490 AU) and disk inclination of 25◦. Assuming the same inclination for the planet candidate’s ∼orbit, its× re-projected× radial distance from the star is∼ 62 AU, very close to the blackbody radius of the outer cold dust ring. The structure of the planetary system at HD 95086 resembles the one around HR 8799. Both systems harbor a warm inner dust belt and a broad colder outer disk and giant planet(s) between the two dusty regions. Modelling implies that the candidate planet can dynamically excite the motion of planetesimals even out to 270 AU via their secular perturbation if its orbital eccentricity is larger than about 0.4. Our analysis adds a new example to the three known systems where directly imaged planet(s) and debris disks co-exist. Accepted by ApJ Letters http://arxiv.org/pdf/1309.1675

Unveiling new members in five nearby young moving groups A. Mo´or1, Gy.M. Szab´o1,2,3, L.L. Kiss1,2,4, Cs. Kiss1, P. Abrah´am´ 1, J. Szul´agyi1, A.´ K´osp´al5, T. Szalai3 1 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, PO Box 67, H-1525 Budapest, Hungary 2 ELTE Gothard-Lendlet Research Group, 9700 Szombathely, Hungary 3 Dept. of Experimental Physics and Astronomical Observatory, 6720 Szeged D´om t´er 9., Hungary 4 Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006, Australia 5 Research and Scientific Support Department, European Space Agency (ESA-ESTEC, SRE-SA), P.O. Box 299, 2200 AG, Noordwijk, The Netherlands ; ESA fellow. E-mail contact: moor at konkoly.hu In the last decade many kinematic groups of young stars (<100 Myr) were discovered in the solar neighbourhood. Since the most interesting period of planet formation overlaps with the age of these groups, their well dated members are attractive targets for exoplanet searches by direct imaging. We combined astrometric, photometric and X-ray data, and applied strict selection criteria to explore the stellar content of five nearby moving groups. We identified

38 more than 100 potential new candidate members in the ß Pic moving group, and in the Tucana-Horologium, Columba, Carina, and Argus associations. In order to further assess and confirm their membership status, we analysed radial velocity data and lithium equivalent widths extracted from high-resolution spectra of 54 candidate stars. We identified 35 new probable/possible young moving group members: 4 in the ß Pic moving group, 11 in the Columba association, 16 in the Carina association, and 4 in the Argus association. We found serendipitiously a new AB Dor moving group member as well. For four Columba systems Hipparcos based parallaxes have already been available and as they are consistent with the predicted kinematic parallaxes, they can be considered as secure new members. Accepted by MNRAS http://arxiv.org/pdf/1309.1669

Near-infrared integral field spectroscopy of Massive Young Stellar Objects K. Murakawa1, S.L. Lumsden1, R.D. Oudmaijer1, B. Davies2, H.E. Wheelwright3, M.G. Hoare1, and J.D. Ilee1,4 1 School of Physics and Astronomy, EC Stoner Building, University of Leeds, Leeds LS2 9JT 2 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA 3 Max-Planck-Institut f¨ur Radioastronomie, Auf dem H¨ugel 69, 53121, Bonn, Germany 4 School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS E-mail contact: k.murakawa at leeds.ac.uk We present medium resolution (R 5300) K-band integral field spectroscopy of six MYSOs. The targets are selected from the RMS survey, and we used≈ the NIFS on the Gemini North telescope. The data show various spectral line features including Brγ, CO, H2, and He i. The Brγ line is detected in emission in all objects with vFWHM 100 – 200 kms−1. V645 Cyg shows a high-velocity P-Cygni profile between -800 kms−1 and -300 kms−1. We performed∼ three-dimensional spectroastrometry to diagnose the circumstellar environment in the vicinity of the central stars using the Brγ line. We measured the centroids of the velocity components with sub-mas precision. The centroids allow us to discriminate the blueshifted and redshifted components in a roughly east–west direction in both IRAS 18151–1208 and S106 in Brγ. This lies almost perpendicular to observed larger scale outflows. We conclude, given the widths of the lines and the orientation of the spectroastrometric signature, that our results trace a disc wind in both IRAS 18151–1208 and S106. The CO ν =2 0 absorption lines at low J transitions are detected in IRAS 18151–1208 and AFGL 2136. We analysed the velocity− structure of the neutral gas discs. In IRAS 18151–1208, the absorption centroids of the blueshifted and redshifted components are separated in a direction of north-east to south-west, nearly perpendicular to that of the larger scale H2 jet. The position-velocity relations of these objects can be reproduced with central masses of 30 M⊙ for IRAS 18151–1208 and 20 M⊙ for AFGL 2136. We also detect CO ν = 2 0 bandhead emission in IRAS 18151–1208, S106 and V645 Cyg. The results can be fitted reasonably with a Keplerian− rotation model, with masses of 15, 20 and 20 M⊙ respectively. Accepted by MNRAS http://arxiv.org/pdf/1309.6139

Bayesian Matching for X-ray and Infrared Sources in the MYStIX Project Tim Naylor1, Patrick S. Broos2 and Eric D. Feigelson2 1 School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK 2 Department of Astronomy & Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 E-mail contact: timn at astro.ex.ac.uk Identifying the infrared counterparts of X-ray sources in Galactic Plane fields such as those of the MYStIX project presents particular difficulties due to the high density of infrared sources. This high stellar density makes it inevitable that a large fraction of X-ray positions will have a faint field star close to them, which standard matching techniques may incorrectly take to be the counterpart. Instead we use the infrared data to create a model of both the field star and counterpart magnitude distributions, which we then combine with a Bayesian technique to yield a probability that any star is the counterpart of an X-ray source. In our more crowded fields, between 10 and 20% of counterparts

39 that would be identified on the grounds of being the closest star to X-ray position within a 99% confidence error circle are instead identified by the Bayesian technique as field stars. These stars are preferentially concentrated at faint magnitudes. Equally importantly the technique also gives a probability that the true counterpart to the X-ray source falls beneath the magnitude limit of the infrared catalog. In deriving our method, we place it in the context of other procedures for matching astronomical catalogs. Accepted by Astrophysical Journal Supplements (MYStIX issue) http://www.astro.psu.edu/mystix http://arxiv.org/pdf/1309.4491

Re-appearance of McNeil’s nebula (V1647 Orionis) and its outburst environment J. P. Ninan1, D. K. Ojha1, B. C. Bhatt2, S. K. Ghosh3, V. Mohan4, K. K. Mallick1, M. Tamura5 and Th. Henning6 1 Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India 2 Indian Institute of Astrophysics, Koramangala, Bangalore 560 034, India 3 National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune 411 007, India 4 Inter-University Centre for Astronomy and Astrophysics, Pune 411 007, India 5 National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan 6 Max-Planck-Institute for Astronomy, K¨onigstuhl 17, 69117 Heidelberg, Germany E-mail contact: ninan at tifr.res.in We present a detailed study of McNeil’s nebula (V1647 Ori) in its ongoing outburst phase starting from September 2008 to March 2013. Our 124 nights of photometric observations were carried out in optical V, R, I and near-infrared (NIR) J, H, K bands, and 59 nights of medium resolution spectroscopic observations were done in 5200 - 9000 A˚ wavelength range. All observations were carried out with 2-m Himalayan Chandra Telescope (HCT) and 2-m IUCAA Girawali Telescope. Our observations show that over last four and a half years, V1647 Ori and the region C near Herbig-Haro object, HH 22A, have been undergoing a slow dimming at a rate of 0.04 mag yr−1 and 0.05 mag yr−1 respectively in R-band, which is 6 times slower than the rate during similar stage∼ of V1647 Ori in 2003∼ outburst. We detected change in flux distribution over the reflection nebula implying changes in circumstellar matter distribution between 2003 and 2008 outbursts. Apart from steady wind of velocity 350 km s−1 we detected two episodic magnetic reconnection driven winds. Forbidden [O I] 6300A˚ and [Fe II] 7155A˚∼lines were also detected implying shock regions probably from jets. We tried to explain the outburst timescales of V1647 Ori using the standard models of FUors kind of outburst and found that pure thermal instability models like Bell & Lin (1994) cannot explain the variations in timescales. In the framework of various instability models we conclude that one possible reason for sudden ending of 2003 outburst in 2005 November was due to a low density region or gap in the inner region ( 1 AU) of the disc. ∼ Accepted by The Astrophysical Journal http://arxiv.org/pdf/1309.4967

The Herschel/PACS view of disks around low-mass stars in Chamaeleon-I J. Olofsson1, L. Sz˝ucs2, Th. Henning1, H. Linz1, I. Pascucci3 and V. Joergens1,2 1 Max Planck Institut f¨ur Astronomie, Koenigstuhl 17, 69117 Heidelberg, Germany 2 Universit¨at Heidelberg, Zentrum f¨ur Astronomie, Institut f¨ur Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany 3 Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721, USA E-mail contact: olofsson at mpia.de Circumstellar disks are expected to be the birthplaces of planets. The potential for forming one or more planets of various masses is essentially driven by the initial mass of the disks, a crucial parameter for any planet formation theory. Constraining the masses of disks is a question of great interest for low-mass stars, which are expected to harbor less massive disks. We present and analyze Herschel/PACS observations of disk-bearing M-type stars that belong to the young 2 Myr old Chamaleon-I star forming region, to better constrain the properties of the circumstellar material ∼

40 and the stellar mass dependance of these parameters. We used the radiative transfer code RADMC to successfully model the spectral energy distributions (SEDs) of 17 M-type stars detected at PACS wavelengths. Based on the modeling results, we first discuss the relatively low detection rates of M5 and later spectral type stars with respect to the PACS sensitivity, and argue their disks masses, or flaring indices, are likely to be low. For M0 to M3 stars, we −4 −3 find a relatively broad range of disk masses (10 –10 M⊙), scale heights, and flaring indices. Via a parametrization of dust stratification, we can reproduce the peak fluxes of the 10 µm emission feature observed with Spitzer/IRS, and find that disks around M-type stars may display signs of dust sedimentation. The Herschel/PACS observations of low-mass stars in Cha-I provide new constraints on their disk properties, overall suggesting that disk parameters for early M-type stars are comparable to those for more massive stars (e.g., comparable scale height and flaring angles). However, regions of the disks emitting at about 100 µm may still be in the optically thick regime, preventing direct determination of disk masses. Thus the modeled disk masses should be considered as lower limits. Still, we are able to extend the wavelength coverage of SED models and start characterizing effects such as dust sedimentation, an effort leading the way towards ALMA observations of these low-mass stars. Accepted by A&A http://www.mpia.de/~olofsson/content/Cha-I.pdf http://arxiv.org/pdf/1310.0834

Radiative accretion shocks along nonuniform stellar magnetic fields in classical T Tauri stars S. Orlando1, R. Bonito2,1, C. Argiroffi2,1, F. Reale2,1, G. Peres2,1, M. Miceli1, T. Matsakos3,4,5, C. Stehl´e5, L. Ibgui5, L. de Sa4,5, J.P. Chi´eze4, and T. Lanz6 1 INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento, 1 , 90134, Palermo, Italy 2 Dip. di Fisica e Chimica, Universit´adegli Studi di Palermo, Piazza del Parlamento, 1, 90134, Palermo, Italy 3 CEA, IRAMIS, Service Photons, Atomes et Mol´ecules, 91191 Gif-sur-Yvette, France 4 Laboratoire AIM, CEA/DSM - CNRS - Universit´eParis Diderot, IRFU/SAp, 91191 Gif-sur-Yvette, France 5 LERMA, Observatoire de Paris, Universit´ePierre et Marie Curie, CNRS, 5 place J. Janssen, 92195 Meudon, France 6 Laboratoire Lagrange, Universit´ede Nice-Sophia Antipolis, CNRS, Observatoire de la Cˆote d’Azur, 06304 Nice cedex 4, France E-mail contact: orlando at astropa.inaf.it Aims. We investigate the dynamics and stability of post-shock plasma streaming along nonuniform stellar magnetic fields at the impact region of accretion columns. We study how the magnetic field configuration and strength determine the structure, geometry, and location of the shock-heated plasma. Methods. We model the impact of an accretion stream onto the chromosphere of a CTTS by 2D axisymmetric magnetohydrodynamic simulations. Our model takes into account the gravity, the radiative cooling, and the magnetic- field-oriented thermal conduction. Results. The structure, stability, and location of the shocked plasma strongly depend on the configuration and strength of the magnetic field. For weak magnetic fields, a large component of B may develop perpendicular to the stream at the base of the accretion column, limiting the sinking of the shocked plasma into the chromosphere. An envelope of dense and cold chromospheric material may also develop around the shocked column. For strong magnetic fields, the field configuration determines the position of the shock and its stand-off height. If the field is strongly tapered close to the chromosphere, an oblique shock may form well above the stellar surface. In general, a nonuniform magnetic field makes the distribution of emission measure vs. temperature of the shocked plasma lower than in the case of uniform magnetic field. Conclusions. The initial strength and configuration of the magnetic field in the impact region of the stream are expected to influence the chromospheric absorption and, therefore, the observability of the shock-heated plasma in the X-ray band. The field strength and configuration influence also the energy balance of the shocked plasma, its emission measure at T > 106 K being lower than expected for a uniform field. The above effects contribute in underestimating the mass accretion rates derived in the X-ray band. Accepted by A&A http://arxiv.org/pdf/1309.5038

41 On the frequency of planetary systems around G-dwarfs Richard J. Parker1 and Sascha P. Quanz1 1 Institute for Astronomy, ETH Z¨urich, Wolfgang-Pauli-Strasse 27, 8093 Z¨urich, Switzerland E-mail contact: rparker at phys.ethz.ch We determine the fraction of G-dwarf stars that could host stable planetary systems based on the observed properties of binaries in the Galactic field, and in various postulated primordial binary populations, which assume that the primordial binary fraction is higher than that in the field. We first consider the frequency of Solar System analogues – planetary systems that form either around a single G-dwarf star, or a binary containing a G-dwarf where the binary separation exceeds 100–300au. If the primordial binary fraction and period distribution is similar to that in the field, then up to 63per cent of G-dwarf systems could potentially host a Solar System analogue. However, if the primordial binary fraction is higher, the fraction of G-dwarf systems that could host a planetary system like our own is lowered to 38per cent. We extend our analysis to consider the fraction of G-dwarf systems (both single and binary) that can host either circumprimary planets (orbiting the primary star of the binary) or circumbinary planets (orbiting both stars in the binary) for fiducial planetary separations between 1 – 100au. Depending on the assumed binary population, in the circumprimary case between 65 and 95per cent of systems can host a planet at 1au, decreasing to between 20 and 65per cent of systems that can host a planet at 100au. In the circumbinary case, between 5 and 59per cent of systems can host a planet at 1au, increasing to between 34 and 75per cent of systems that can host a planet at 100au. Our results suggest that the assumed binary fraction is the key parameter in determining the fraction of potentially stable planetary systems in G-dwarf systems and that using the present-day value may lead to significant overestimates if the binary fraction was initially higher. Accepted by MNRAS http://arxiv.org/pdf/1308.6279

Molecular line and continuum study of the W40 cloud L. Pirogov1, D.K. Ojha2, M. Thomasson3, Y.-F. Wu4, and I. Zinchenko1 1 Institute of Applied Physics RAS, Ulyanova 46, Nizhny Novgorod 603950, Russia 2 Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai 400005, India 3 Chalmers University of Technology, Department of Radio and Space Science, Onsala Space Observatory, 43992 Onsala, Sweden 4 Department of Astronomy, School of Physics, Peking University, Beijing, 100871, China E-mail contact: pirogov at appl.sci-nnov.ru The dense cloud associated with W40, one of the nearby H II regions, has been studied in millimeter-wave molecular lines and in 1.2 mm continuum. Besides, 1280 MHz and 610 MHz interferometric observations have been done. The cloud has complex morphological and kinematical structure, including a clumpy dust ring and an extended dense core. The ring is probably formed by the“collect and collapse” process due to the expansion of neighboring H II region. Nine dust clumps in the ring have been deconvolved. Their sizes, masses and peak hydrogen column densities are: 22 −2 0.02 0.11 pc, 0.4 8.1M⊙ and (2.5 11) 10 cm , respectively. Molecular lines are observed at two different∼ − velocities∼ and have− different spatial∼ distributions− × implying strong chemical differentiation over the region. + 13 + The CS abundance is enhanced towards the eastern dust clump 2, while the NH3, N2H , and H CO abundances are enhanced towards the western clumps. HCN and HCO+ do not correlate with the dust probably tracing the surrounding gas. Number densities derived towards selected positions are: (0.3 3.2) 106 cm−3. Two western clumps have kinetic temperatures 21 K and 16 K and are close to virial equilibrium.∼ − The eastern× clumps 2 and 3 are more massive, have higher extent of turbulence and are probably more evolved than the western ones. They show asymmetric CS(2–1) line profiles due to infalling motions which is confirmed by model calculations. An interaction between ionized and neutral material is taking place in the vicinity of the eastern branch of the ring and probably trigger star formation. Accepted by MNRAS http://arxiv.org/pdf/1309.6188

42 Magnetic Field Components Analysis of the SCUPOL 850 µm Polarization Data Catalog Fr´ed´erick Poidevin1, Diego Falceta-Gon¸calves2,3, Grzegorz Kowal3, Elisabete de Gouveia Dal Pino4 and Antonio-M´ario Magalh˜aes4 1 University College London, Kathleen Lonsdale Building, Department of Physics & Astronomy, Gower Place, London WC1E 6BT, United Kingdom 2 SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK 3 Universidade de S˜ao Paulo,- Escola de Artes, Ciˆencias e Humanidades Rua Arlindo B´ettio, no. 1000 - Ermelino Matarazzo - S˜ao Paulo - SP 03828-000 , Brazil 4 Universidade de S˜ao Paulo, Instituto de Astronomia, Geof´ısica e Cˆıen¸cas Atmosf´ericas, Rua do Mat˜ao 1226, Butant˜a, S˜ao Paulo, SP 05508-900, Brazil E-mail contact: Poidevin at star.ucl.ac.uk We present an extensive analysis of the 850 µm polarization maps of the SCUPOL Catalog produced by Matthews et al. (2009), focusing exclusively on the molecular clouds and star-forming regions. For the sufficiently sampled regions, we characterize the depolarization properties and the turbulent-to-mean magnetic field ratio of each region. Similar sets of parameters are calculated from 2D synthetic maps of dust emission polarization produced with 3D MHD numerical simulations scaled to the S106, OMC-2/3, W49 and DR21 molecular clouds polarization maps. For these specific regions the turbulent MHD regimes retrieved from the simulations, as described by the turbulent Alfv´en and sonic Mach numbers, are consistent within a factor 1 to 2 with the values of the same turbulent regimes estimated from the analysis of Zeeman measurements data provided by Crutcher (1999). Constraints on the values of the inclination angle α of the mean magnetic field with respect to the LOS are also given. The values obtained from the comparison of the simulations with the SCUPOL data are consistent with the estimates made by use of two different observational methods provided by other authors. Our main conclusion is that simple ideal, isothermal and non-selfgraviting MHD simulations are sufficient to describe the large scale observed physical properties of the envelopes of this set of regions. Accepted by the ApJ http://arxiv.org/pdf/1309.1047

The MYStIX InfraRed-Excess Source Catalog Matthes S. Povich1,2, Michael A. Kuhn2, Konstantin V. Getman2, Heather A. Busk2, Eric D. Feigelson2, Patrick S. Broos2, Leisa K. Townsley2, Robert R. King3 and Tim Naylor3 1 California State Polytechnic University, 3801 West Temple Ave, Pomona, CA 91768 2 Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 3 School of Physics, University of Exeter, Exeter EX4 4QL, UK E-mail contact: mspovich at csupomona.edu The MYStIX project (Massive Young Star-Forming Complex Study in Infrared and X-rays) provides a comparative study of 20 Galactic massive star-forming complexes (d = 0.4 to 3.6 kpc). Probable stellar members in each target complex are identified using X-ray and/or infrared data via two pathways: (1) X-ray detections of young/massive stars with coronal activity/strong winds; or (2) infrared excess (IRE) selection of young stellar objects (YSOs) with circum- stellar disks and/or protostellar envelopes. We present the methodology for the second pathway, using Spitzer/IRAC, 2MASS, and UKIRT imaging and photometry. Although IRE selection of YSOs is well- trodden territory, MYStIX presents unique challenges. The target complexes range from relatively nearby clouds in uncrowded fields located toward the outer Galaxy (e.g. NGC 2264, the Flame Nebula) to more distant, massive complexes situated along com- plicated, inner Galaxy sightlines (e.g. NGC 6357, M17). We combine IR spectral energy distribution (SED) fitting with IR color cuts and spatial clustering analysis to identify IRE sources and isolate probable YSO members in each MYStIX target field from the myriad types of contaminating sources that can resemble YSOs: extragalactic sources, evolved stars, nebular knots, and even unassociated foreground/background YSOs. Applying our methodology con- sistently across 18 of the target complexes, we produce the MYStIX IRE Source (MIRES) Catalog comprising 20,719 sources, including 8686 probable stellar members of the MYStIX target complexes. We also classify the SEDs of 9365 IR counterparts to MYStIX X-ray sources to assist the first pathway, the identification of X-ray-detected stellar members. The MIRES catalog provides a foundation for follow-up studies of diverse phenomena related to massive

43 star cluster formation, including protostellar outflows, circumstellar disks, and sequential star formation triggered by massive star feedback processes. Accepted by Astrophysical Journal Supplements (MYStIX issue) http://www.astro.psu.edu/mystix http://arxiv.org/pdf/1309.4497

Structure, stability and evolution of 3D Rossby vortices in protoplanetary disks S. Richard1, P. Barge1, and S. Le Diz´es2 1 Aix Marseille Universit´e, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 38 rue F. Joliot-Curie, F-13388 Marseille, Cedex 13, France 2 Aix Marseille Universit´e, CNRS, Centrale Marseille, IRPHE (Institut de Recherche sur les Ph´enom`enes Hors Equi- libre) UMR 7342, 49 rue F. Joliot Curie, F-13013 Marseille, France E-mail contact: samuel.richard at oamp.fr Large-scale persistent vortices are known to form easily in 2D disks via the Rossby wave or the baroclinic instability. In 3D, however, their formation and stability is a complex issue and still a matter of debate. We study the formation of vortices by the Rossby wave instability in a stratified inviscid disk and describe their three dimensional structure, stability and long term evolution. Numerical simulations are performed using a fully compressible hydrodynamical code based on a second order finite volume method. We assume a perfect gas law and a non-homentropic adiabatic flow.The Rossby wave instability is found to proceed in 3D in a similar way as in 2D. Vortices produced by the instability look like columns of vorticity in the whole disk thickness; the small vertical motions are related to a weak inclination of the vortex axis appearing during the development of the RWI. Vortices with aspect ratios larger than 6 are unaffected by the elliptical instability. They relax to a quasi-steady columnar structure which survives hundred of rotations while slowly migrating inward toward the star at a rate that reduces with the vortex aspect ratio. Vortices with a smaller aspect ratio are by contrast affected by the elliptic instability. Short aspect ratio vortices are completely destroyed in a few orbital periods. Vortices with an intermediate aspect ratio are partially destroyed by the elliptical instability in a region away from the mid-plane where the disk stratification is sufficiently large. Elongated Rossby vortices can survive a large number of orbital periods in protoplanetary disks in the form of vorticity columns. They could play a significant role in the evolution of the gas and the gathering of the solid particles to form planetesimals or planetary cores, a possibility that receives a renewed interest with the recent discovery of a particle trap in the disk of Oph IRS48. Accepted by A&A http://arxiv.org/pdf/1309.3486

Long-Baseline Interferometric Multiplicity Survey of the Sco-Cen OB Association A.C. Rizzuto1, M.J. Ireland1,3, J.G. Robertson2, Y. Kok2, P.G. Tuthill2, B.A. Warrington1, X. Haubois2, W.J. Tango2, B. Norris2, T. ten Brummelaar5, A.L. Kraus4, A. Jacob2, and C. Laliberte-Houdeville2 1 Department of Physics and Astronomy, Macquarie University, Sydney NSW, 2109, Australia 2 Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney NSW, 2006, Australia 3 Australian Astronomical Observatory, Epping NSW 2121, Australia 4 The University of Texas, Department of Astronomy, Austin, Texas 78712, USA 5 Center for High Angular Resolution Astronomy, Georgia State University, P.O. Box 3969, Atlanta, GA 30302, USA E-mail contact: aaron.rizzuto at mq.edu.au We present the first multiplicity-dedicated long baseline optical interferometric survey of the Scorpius-Centaurus- Lupus-Crux association. We used the Sydney University Stellar Interferometer to undertake a survey for new com- panions to 58 Sco-Cen B- type stars and have detected 24 companions at separations ranging from 7–130 mas, 14 of which are new detections. Furthermore, we use a Bayesian analysis and all available information in the literature to determine the multiplicity distribution of the 58 stars in our sample, showing that the companion frequency is F = 1.35 and the mass ratio distribution is best described as a power law with exponent equal to 0.46, agreeing with previous Sco-Cen high mass work and differing significantly from lower-mass stars in Tau-Aur. Based− on our analysis,

44 we estimate that among young B-type stars in moving groups, up to 23% are apparently single stars. This has strong implications for the understanding of high-mass star formation, which requires angular momentum dispersal through some mechanism such as formation of multiple systems. Accepted by MNRAS http://arxiv.org/pdf/1309.3811

New Radio Continuum Observations of the Compact Source Projected Inside NGC 6334A Luis F. Rodr´ıguez1,2, Josep M. Masqu´e1, Sergio A. Dzib1, Laurent Loinard1 and Stanley E. Kurtz1 1 Centro de Radioastronom´ıay Astrof´ısica, Universidad Nacional Aut´onoma de M´exico, Campus Morelia, Mexico 2 Astronomy Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia E-mail contact: l.rodriguez at crya.unam.mx A handful of HII regions are known to exhibit a compact radio source near their centers. The nature of these compact radio sources is not well established. We present the analysis of new as well as archival Very Large Array observations of the compact source projected near the center of the NGC 6334A HII region, part of the NGC 6334 complex. We show that the compact source is time variable on a scale of years and determine for one epoch a non-thermal spectrum, suggestive of synchrotron emission. We propose that this source could be the wind interaction region of a massive binary system that could be the ionizing source of NGC 6334A. Accepted by Revista Mexicana de Astronom´ıay Astrof´ısica http://arxiv.org/pdf/1309.4764

ALMA Observations of the IRDC Clump G34.43+00.24 MM3: Hot Core and Molecular Outflows Takeshi Sakai1, Nami Sakai2, Jonathan B. Foster3, Patricio Sanhueza4, James M. Jackson4, Marc Kassis5, Kenji Furuya6, Yuri Aikawa6, Tomoya Hirota7 and Satoshi Yamamoto2 1 Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofu, Tokyo 182- 8585, Japan 2 Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan 3 Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT 06520, USA 4 Institute for Astrophysical Research, Boston University, Boston, MA 02215, USA 5 W. M. Keck Observatory, 65-1120 Mamalahoa Hwy., Kamuela, HI 96743, USA 6 Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501, Japan 7 National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588, Japan E-mail contact: takeshi.sakai at uec.ac.jp We have observed a cluster forming clump (MM3) associated with the infrared dark cloud G34.43+00.24 in the 13 1.3 mm continuum and the CH3OH, CS, CS, SiO, CH3CH2CN, and HCOOCH3 lines with the Atacama Large Millimeter/submillimeter Array and in K-band with the Keck telescope. We have found a young outflow toward the center of this clump in the SiO, CS, and CH3OH lines. This outflow is likely driven by a protostar embedded in a 13 hot core, which is traced by the CH3CH2CN, HCOOCH3, CS, and high excitation CH3OH lines. The size of the hot core is about 800 300 AU in spite of its low mass (<1.1 M⊙), suggesting a high accretion rate or the presence of multiple star system× harboring a few hot corinos. The outflow is highly collimated, and the dynamical timescale is estimated to be less than 740 yr. In addition, we have also detected extended emission of SiO, CS, and CH3OH, which is not associated with the hot core and the outflow. This emission may be related to past star formation activity in the clump. Although G34.43+00.24 MM3 is surrounded by a dark feature in infrared, it has already experienced active formation of low-mass stars in an early stage of clump evolution. Accepted by ApJ http://arxiv.org/pdf/1309.2804

45 Correlating Infall with Deuterium Fractionation in Dense Cores Scott Schnee1, Nathan Brunetti1, James Di Francesco2,3, Paola Caselli4, Rachel Friesen1,5, Doug Johnstone2,3,6, and Andy Pon2,3,4 1 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA 2 National Research Council Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road Victoria, BC V9E 2E7, Canada 3 Department of Physics & Astronomy, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada 4 School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK 5 Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto M5S 3H4, Ontario, Canada 6 Joint Astronomy Centre, 660 North Aohoku Place, University Park, Hilo, HI 96720, USA E-mail contact: sschnee at nrao.edu + + We present a survey of HCO (3–2) observations pointed towards dense cores with previous measurements of N(N2D ) + / N(N2H ). Of the 26 cores in this survey, five show the spectroscopic signature of outward motion, nine exhibit neither inward nor outward motion, eleven appear to be infalling, and one is not detected. We compare the degree of deuterium fractionation with infall velocities calculated from the HCO+ spectra and find that those cores with [D]/[H] > 0.1 are more likely to have the signature of inward motions than cores with smaller [D]/[H] ratios. Infall motions are also much more common in cores with masses exceeding their thermal Jeans masses. The fastest infall velocity measured belongs to one of the two protostellar cores in our survey, L1521F, and the observed motions are typically on the order of the sound speed. Accepted by ApJ http://arxiv.org/pdf/1309.4103

Substellar Objects in Nearby Young Clusters VII: The substellar mass function revisited Alexander Scholz1,2, Vincent Geers1, Paul Clark3, Ray Jayawardhana4 and Koraljka Muzic5 1 School of Cosmic Physics, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland 2 School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom 3 Zentrum f¨ur Astronomie der Universit¨at Heidelberg, Institut f¨ur Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg, Germany 4 Department of Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada 5 European Southern Observatory, Alonso de C´ordova 3107, Casilla 19, 19001, Santiago, Chile E-mail contact: as110 at st-andrews.ac.uk The abundance of brown dwarfs (BDs) in young clusters is a diagnostic of star formation theory. Here we revisit the issue of determining the substellar initial mass function (IMF), based on a comparison between NGC1333 and IC348, two clusters in the Perseus star-forming region. We derive their mass distributions for a range of model isochrones, varying distances, extinction laws and ages, with comprehensive assessments of the uncertainties. We find that the choice of isochrone and other parameters have significant effects on the results, thus we caution against comparing IMFs obtained using different approaches. For NGC1333, we find that the star/BD ratio R is between 1.9 and 2.4, for all plausible scenarios, consistent with our previous work. For IC348, R is found to be between 2.9 and 4.0, suggesting that previous studies have overestimated this value. Thus, the star forming process generates about 2.5-5 substellar objects per 10 stars. The derived star/BD ratios correspond to a slope of the power-law mass function of α =0.7 1.0 for the 0.03-1.0 M⊙ mass range. The median mass in these clusters – the typical stellar mass – is between − 0.13-0.30 M⊙. Assuming that NGC1333 is at a shorter distance than IC348, we find a significant difference in the cumulative distribution of masses between the two clusters, resulting from an overabundance of very low mass objects in NGC1333. Gaia astrometry will constrain the cluster distances better and will lead to a more definitive conclusion. Furthermore, the star/BD ratio is somewhat larger in IC348 compared with NGC1333, although this difference is still within the margins of error. Our results indicate that environments with higher object density may produce a

46 larger fraction of very low mass objects, in line with predictions for brown dwarf formation through gravitational fragmentation of filaments falling into a cluster potential. Accepted by Astrophysical Journal http://arxiv.org/pdf/1309.0823

Aligned grains and inferred toroidal magnetic fields in the envelopes of massive young stellar objects Janet P. Simpson1, Barbara A. Whitney2, Dean C. Hines3, Glenn Schneider4, Michael G. Burton5, Sean W. J. Colgan6, Angela S. Cotera1, Edwin F. Erickson6 and Michael J. Wolff7 1 SETI Institute, 189 Bernardo Ave, Mountain View, CA 94043, USA 2 University of Wisconsin, USA 3 Space Telescope Science Institute, USA 4 University of Arizona, USA 5 NASA Ames Research Center, USA 6 University of New South Wales, Australia 7 Space Science Institute, USA E-mail contact: jsimpson at seti.org Massive young stellar objects (YSOs), like low-mass YSOs, are thought to be surrounded by optically thick envelopes and/or discs and are observed to have associated regions that produce polarized light at near-infrared wavelengths. These polarized regions are thought to be lower-density outflows along the polar axes of the YSO envelopes. Using the 0.2 arcsec spatial resolution of the Near-Infrared Camera and Multi-Object Spectrometer on the Hubble Space Telescope we are examining the structure of the envelopes and outflow regions of massive YSOs in star-forming regions within a few kpc of the Sun. Here we report on 2 micron polarimetry of Mon R2-IRS3, S140-IRS1, and AFGL 2591. All three sources contain YSOs with highly-polarized monopolar outflows, with Mon R2-IRS3 containing at least two YSOs in a small cluster. The central stars of all four YSOs are also polarized, with position angles perpendicular to the directions of the outflows. We infer that this polarization is due to scattering and absorption by aligned grains. We have modelled our observations of S140-IRS1 and AFGL 2591 as light scattered and absorbed both by spherical grains and by elongated grains that are aligned by magnetic fields. Models that best reproduce the observations have a substantial toroidal component to the magnetic field in the equatorial plane. Moreover, the toroidal magnetic field in the model that best fits AFGL 2591 extends a large fraction of the height of the model cavity, which is 105 au. We conclude that the massive YSOs in this study all show evidence of the presence of a substantial toroidal magnetic field. Accepted by MNRAS http://arxiv.org/pdf/1309.0856

The Dynamical State of The Serpens South Filamentary Infrared Dark Cloud Tomohiro Tanaka1, Fumitaka Nakamura2,3, Yuya Awazu1, Yoshito Shimajiri3, Koji Sugitani4, Toshikazu Onishi1, Ryohei Kawabe2,3,5, Hiroshige Yoshida6 and Aya E. Higuchi5 1 Department of Physical Science, Osaka Prefecture University, Gakuen 1-1, Sakai, Osaka 599-8531, Japan 2 National Astronomical Observatory, Mitaka, Tokyo 181-8588, Japan; [email protected] 3 Nobeyama Radio Observatory, Minamimaki, Minamisaku, Nagano 384-1805, Japan 4 Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501, Japan 5 Joint ALMA Observatory, Alonso de Cordova 3107 OFC 129, Vitacura, Chile 6 Caltech Submillimeter Observatory, 111 Nowelo St. Hilo HI 96720 U.S.A. E-mail contact: s t.tanaka at p.s.osakafu-u.ac.jp + We present the results of N2H (J =1 0) observations toward Serpens South, the nearest cluster-forming, infrared − + dark cloud. The physical quantities are derived by fitting the hyperfine structure of N2H . The Herschel and 1.1-mm continuum maps show that a pc-scale filament fragments into three clumps with radii of 0.1 0.2 pc and masses of − 40 230M⊙. We find that the clumps contain smaller-scale ( 0.04 pc) structures, i.e., dense cores. We identify − ∼

47 + 70 cores by applying CLUMPFIND to the N2H data cube. In the central cluster-forming clump, the excitation temperature and line-width tend to be large, presumably due to protostellar outflow feedback and stellar radiation. However, for all the clumps, the virial ratios are evaluated to be 0.1 0.3, indicating that the internal motions play only a minor role in the clump support. The clumps exhibit no free-fall,− but low-velocity infall, and thus the clumps should be supported by additional forces. The most promising force is the globally-ordered magnetic field observed toward this region. We propose that the Serpens South filament was close to magnetically-critical and ambipolar diffusion triggered the cluster formation. We find that the northern clump, which shows no active star formation, has a mass and radius comparable to the central cluster-forming clump, and therefore, it is a likely candidate of a pre-protocluster clump. The initial condition for cluster formation is likely to be a magnetically-supported clump of cold, quiescent gas. This appears to contradict the accretion-driven turbulence scenario, for which the turbulence in the clumps is maintained by the accretion flow. Accepted by ApJ http://arxiv.org/pdf/1309.2425

Chemical Variation in Molecular Cloud Cores in the Orion A Cloud. II Ken’ichi Tatematsu1, Satoshi Ohashi2, Tomofumi Umemoto1, Jeong-Eun Lee3, Tomoya Hirota1, Satoshi Yamamoto4, Minho Choi5, Ryo Kandori1 and Norikazu Mizuno1 1 National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 2 Department of Astronomy, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan 3 School of Space Research, Kyung Hee University, Seocheon-Dong, Giheung-Gu, Yongin-Si, Gyeonggi-Do, 446-701, South Korea 4 Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan 5 Korea Astronomy and Space Science Institute, Daedeokdaero 776, Yuseong, Daejeon 305-348, South Korea E-mail contact: k.tatematsu at nao.ac.jp We have mapped six molecular cloud cores in the Orion A giant molecular cloud (GMC), whose kinetic temperatures + range from 10 to 30 K, in CCS and N2H with Nobeyama 45 m radio telescope to study their chemical characteristics. + We identified 31 intensity peaks in the CCS and N2H emission in these molecular cloud cores. It is found for cores + with temperatures lower than 25 K that the column density ratio of N(N2H )/N(CCS) is low toward starless ∼ + core regions while it is high toward star-forming core regions, in case that we detected both of the CCS and N2H emission. This is very similar to the tendency found in dark clouds (kinetic temperature 10 K). The criterion found + ∼ in the Orion A GMC is N(N2H )/N(CCS) 2 3. In some cases, the CCS emission is detected toward protostars + ∼ − as well as the N2H emission. Secondary late-stage CCS peak in the chemical evolution caused by CO depletion may + be a possible explanation for this. We found that the chemical variation of CCS and N2H can also be used as a + tracer of evolution in warm (10 25 K) GMC cores. On the other hand, some protostars do not accompany N2H − + intensity peaks but are associated with dust continuum emitting regions, suggesting that the N2H abundance might be decreased due to CO evaporation in warmer star-forming sites. Accepted by PASJ http://arxiv.org/pdf/1309.7541

The effects of disc warping on the inclination of planetary orbits Caroline Terquem1,2 1 Department of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK 2 Institut d’Astrophysique de Paris, UPMC Univ Paris 06, CNRS, UMR7095, 98 bis bd Arago, F-75014, Paris, France E-mail contact: caroline.terquem at astro.ox.ac.uk The interaction between a planet located in the inner region of a disc and the warped outer region is studied. We consider the stage of evolution after the planet has cleared-out a gap, so that the planetary orbit evolves only under the gravitational potential from the disc. We develop a secular analysis and compute the evolution of the orbital elements by solving Lagrange’s equations valid to second order in the eccentricity. We also perform numerical simulations with the full disc potential. In general, the interaction between the disc and the planet leads to the precession of the

48 orbit. The orbital plane therefore becomes tilted relative to the disc’s inner parts, with no change in the eccentricity. When the inclination approaches 90 degrees, there is an instability and the eccentricity increases. In this case, both the inclination and the eccentricity develop large variations, with the orbit becoming retrograde. As the eccentricity reaches high values, we would expect tidal capture on a short orbit of the planet by the star to occur. This instability happens when the disc is severely warped, or if there is a significant amount of mass in a ring inclined by at least 45 degrees relative to the initial orbital plane. The inclination of the orbit does not depend on the semimajor axis nor on the planet’s mass. However, for a significant inclination to be generated on a timescale of at most a few Myr, the planet should be beyond the snow line. The process described here would therefore produce two distinct populations of inclined planets: one with objects beyond the snow line with at most moderate eccentricities, and another with objects on short circularized orbits. Accepted by MNRAS http://arxiv.org/pdf/1309.1025

Gas lines from the 5-Myr old optically thin disk around HD141569A. Herschel obser- vations and modeling W.-F. Thi1, C. Pinte1, E. Pantin2, J.C. Augereau1, G. Meeus3, F. M´enard1,4, C. Martin-Za¨ıdi1 , P. Woitke5, P. Riviere-Marichalar6I. Kamp6, A. Carmona1, G. Sandell7, C. Eiroa3, W. Dent8, B. Montesinos3, G. Aresu6, R. Meijerink6, M. Spaans6, G. White9,10, D. Ardila11, J. Lebreton1, I. Mendigut´ıa12, S. Brittain12 1 UJF-Grenoble 1 / CNRS-INSU, Institut de Plantologie et dAstrophysique (IPAG) UMR 5274, Grenoble, F-38041, France 2 Laboratoire AIM, CEA/DSM - CNRS - Universit Paris Diderot, IRFU/SAP, F-91191 sur Yvette, France 3 Dep. de F´ısica Te´orica, Fac. de Ciencias, UAM Campus Cantoblanco, 28049 Madrid, Spain 4 UMI LFCA, CNRS / INSU France, and Dept. de Astronomia y Obs. Astronomico Nacional, Universidad de Chile, Casilla 36-D, Correo Central, Santiago, Chile (UMI 3386) 5 SUPA, School of Physics & Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS, UK 6 Kapteyn Astronomical Institute, P.O. Box 800, 9700 AV Groningen, The Netherlands 7 SOFIA-USRA, NASA Ames Research Center, Mail Stop N211-3, Building N211/Rm. 249, Moffett Field, CA 94035, USA 8 ALMA, Avda Apoquindo 3846, Piso 19, Edificio Alsacia, Las Condes, Santiago, Chile 9 Astrophysics Group, Department of Physics & Astronomy, The Open University, UK 10 RAL Space, The Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK 11 NASA Herschel Science Center, California Institute of Technology, Mail Code 100-22, Pasadena, CA 91125, USA 12 Department of Physics and Astronomy, 118 Kinard Laboratory, Clemson University, Clemson, SC 29634, USA E-mail contact: Wing-Fai.Thi at obs.ujf-grenoble.fr At the distance of 99–116 pc, HD141569A is one of the nearest Herbig Ae stars that is surrounded by a tenuous disk, probably in transition between a massive primordial disk and a debris disk. We observed the fine-structure lines of O i at 63 and 145 µm and the C ii line at 157 µm with the PACS instrument onboard the Herschel Space Telescope as part of the open-time large programme GASPS. We complemented the atomic line observations with archival Spitzer spectroscopic and photometric continuum data, a ground-based VLT-VISIR image at 8.6 µm, and 12CO fundamental ro-vibrational and pure rotational J=3–2 observations. We simultaneously modeled the continuum emission and the line fluxes with the Monte Carlo radiative transfer code MCFOST and the thermo-chemical code ProDiMo to derive the disk gas- and dust properties assuming no dust settling. The models suggest that the oxygen lines are emitted from the inner disk around HD141569A, whereas the [C ii] line emission is more extended. The CO submillimeter flux is emitted mostly by the outer disk. Simultaneous modeling of the photometric and line data using a realistic disk −7 structure suggests a dust mass derived from grains with a radius smaller than 1 mm of 2.1 10 M⊙ and from grains −6 × with a radius of up to 1 cm of 4.9 10 M⊙. We constrained the polycyclic aromatic hydrocarbons (PAH) mass to −11 −×10 be between 2 10 and 1.4 10 M⊙ assuming circumcircumcoronene (C150H30) as the representative PAH. The associated PAH× abundance relative× to hydrogen is lower than those found in the interstellar medium (3 10−7) by −4 × two to three orders of magnitude. The disk around HD141569A is less massive in gas (2.5 to 4.9 10 M⊙ or 67 to 164 M⊕) and has a flat opening angle (<10%). [abridged]

49 Accepted by A&A http://arxiv.org/pdf/1309.5098

Thermal and non-thermal emission in the Cygnus X region W.F. Xu1,2, X.Y. Gao2, J.L. Han2, and F.S. Liu1 1 College of Physical Science and Technology, Shenyang Normal University, Shenyang 110034, PR China 2 National Astronomical Observatories, Chinese Academy of Sciences, Jia-20 Datun Road, Chaoyang District, Beijing 100012, PR China E-mail contact: bearwards at gmail.com Radio continuum observations detect non-thermal synchrotron and thermal bremsstrahlung radiation. Separation of the two different emission components is crucial to study the properties of diffuse interstellar medium. The Cygnus X region is one of the most complex areas in the radio sky which contains a number of massive stars and HII regions on the diffuse thermal and non-thermal background. More supernova remnants are expected to be discovered. We aim to develop a method which can properly separate the non-thermal and thermal radio continuum emission and apply it to the Cygnus X region. The result can be used to study the properties of different emission components and search for new supernova remnants in the complex. Multi-frequency radio continuum data from large-scale surveys are used to develop a new component separation method. Spectral analysis is done pixel by pixel for the non-thermal synchrotron emission with a realistic spectral index distribution and a fixed spectral index of β = 2.1 for the thermal bremsstrahlung emission. With the new method, we separate the non-thermal and thermal components− of the Cygnus X region at an angular resolution of 9.′5. The thermal emission component is found to comprise 75% of the total continuum emission at 6cm. Thermal diffuse emission, rather than the discrete HII regions, is found to be the major contributor to the entire thermal budget. A smooth non-thermal emission background of 100 mK Tb is found. We successfully make the large-extent known supernova remnants and the HII regions embedded in the complex standing out, but no new large SNRs brighter than Σ =3.7 10−21 W m−2 Hz−1 sr−1 are found. 1GHz × Accepted by A&A http://arxiv.org/pdf/1309.6065

Young Stars Near Earth: The Octans-Near Association and Castor Moving Group B. Zuckerman1, Laura Vican1, Inseok Song2, and Adam Schneider3 1 Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA 2 Department of Physics and Astronomy, University of Georgia, Athens, GA 30602-2451, USA 3 Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA E-mail contact: ben at astro.ucla.edu All cataloged stellar moving groups and associations with ages <100 Myr and within 100 pc of Earth have Galactic space motions (UVW) situated in a “good box” with dimensions 20 km s−1 on a side. Torres et al. defined the Octans Association as a group of 15 stars with age “20 Myr?” and∼ located 140 pc from Earth, but with average V space velocity 3.6kms−1 that is well outside of the good box. We present∼ a list of 14 Hipparcos star systems within 100 pc of Earth− that we call “Octans-Near”; these systems have UVW similar to those of the much more distant Octans Association. The Octans-Near stars have apparent ages between about 30 and 100 Myr and their relationship to the Octans Association stars is unclear. Six additional star systems have UVW similar to those of Octans-Near stars and likely ages <200 Myr. These six systems include the late-type binary star EQ Peg – 6.2 pc from Earth with likely age <100 Myr and thus likely to be the nearest known pre-main sequence star system. The UVW of stars in a previously proposed 200 Myr old Castor moving group are not too dissimilar from the UVW of Octans-Near stars. However, stars in the∼ Castor group – if it exists at all – are mostly substantially older than 200 Myr and thus generally can readily be distinguished from the much younger Octans-Near stars. Accepted by ApJ http://arxiv.org/pdf/1309.2318

50 Abstracts of recently accepted major reviews

Astrobiology: An Astronomer’s Perspective Edwin A. Bergin1 1 University of Michigan, Department of Astronomy, 500 Church Street, Ann Arbor MI 48109, USA E-mail contact: ebergin at umich.edu In this review we explore aspects of the field of astrobiology from an astronomical viewpoint. We therefore focus on the origin of life in the context of planetary formation, with additional emphasis on tracing the most abundant volatile elements, C, H, O, and N that are used by life on Earth. We first explore the history of life on our planet and outline the current state of our knowledge regarding the delivery of the C, H, O, N elements to the Earth. We then discuss how astronomers track the gaseous and solid molecular carriers of these volatiles throughout the process of star and planet formation. It is now clear that the early stages of star formation fosters the creation of water and simple organic molecules with enrichments of heavy isotopes. These molecules are found as ice coatings on the solid materials that represent microscopic beginnings of terrestrial worlds. Based on the meteoritic and cometary record, the process of planet formation, and the local environment, lead to additional increases in organic complexity. The astronomical connections towards this stage are only now being directly made. Although the exact details are uncertain, it is likely that the birth process of star and planets likely leads to terrestrial worlds being born with abundant water and organics on the surface. Accepted by XVII Special Courses at the National Observatory of Rio de Janeiro. AIP Conference Proceedings. http://xxx.lanl.gov/pdf/1309.4729

Angular momentum evolution of young low-mass stars and brown dwarfs: observations and theory J. Bouvier1, S.P. Matt2, S. Mohanty3, A. Scholz4, K.G. Stassun5 and C. Zanni6 1 IPAG, Grenoble, France 2 Exeter University, UK 3 Imperial College London, UK 4 University of St Andrews, UK 5 Vanderbilt University, USA 6 Osservatorio Astrofisico di Torino, Italy E-mail contact: Jerome.Bouvier at obs.ujf-grenoble.fr This chapter aims at providing the most complete review of both the emerging concepts and the latest observational results regarding the angular momentum evolution of young low-mass stars and brown dwarfs. In the time since Protostars & Planets V, there have been major developments in the availability of rotation period measurements at multiple ages and in different star-forming environments that are essential for testing theory. In parallel, substantial theoretical developments have been carried out in the last few years, including the physics of the star-disk interaction, numerical simulations of stellar winds, and the investigation of angular momentum transport processes in stellar interiors. This chapter reviews both the recent observational and theoretical advances that prompted the development of renewed angular momentum evolution models for cool stars and brown dwarfs. While the main observational trends of the rotational history of low mass objects seem to be accounted for by these new models, a number of critical open issues remain that are outlined in this review. Accepted by Protostars & Planets VI, 2014, University of Arizona Press, eds. H. Beuther, R. Klessen, K. Dullemond, Th. Henning http://arxiv.org/pdf/1309.7851

51 Dissertation Abstracts

Probing the Initial Conditions of Massive Star and Star Cluster Formation: A Combined Approach of Mid-Infrared Extinction Mapping and Numerical Simulation

Michael Butler

University of Florida Institute for Theoretical Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zrich, Switzerland Electronic mail: butler85 at ufl.edu Ph.D dissertation directed by: Jonathan C. Tan Ph.D degree awarded: August 2013

Understanding the formation processes of massive star and star clusters in giant molecular clouds (GMCs) is of vital importance to the subject of galaxy evolution, but despite this importance many open questions remain. In order to address these topics, an understanding of the initial conditions from which massive stars and star clusters form is needed. We investigate these initial conditions from two directions: first, an observational study focused on massive starless (or early stage) clumps and cores within GMCs that reveal themselves as Infrared Dark Clouds (IRDCs), and second, a theoretical/numerical study focused on the formation and dynamics of these structures. An important aspect of this work is the convergence and comparison of the results from these two approaches. We present a method of mid-infrared extinction mapping of IRDCs, which are thought to represent the initial conditions of massive star and star cluster formation. This technique involves modeling the diffuse Galactic background intensity at 8 µ m behind the dark cloud, assessing the foreground emission, and then using the observed cloud intensities to calculate the optical depth through the cloud. The optical depth is then converted to the mass surface density, Σ, by assuming a dust opacity and gas-to-dust ratio. We present maps of Σ for ten of the most massive, high contrast IRDCs from the sample of Rathborne et al. (2006). The masses derived from our extinction maps are then compared to those derived from millimeter emission, finding generally good agreement. The second part of the dissertation presents the results of a numerical study of cloud formation and evolution that utilizes the adaptive mesh refinement hydrodynamic code Enzo to simulate a kiloparsec-scale box extracted from a global galaxy disk simulation. By following the evolution of this region to high 0.1 pc resolution, the structure and dynamics of clumps within GMCs can be analyzed and compared to our observational∼ results. We explore the effects of realistic heating and cooling functions that include the effects of molecular line and dust cooling (e.g. tracking the atomic to molecular phase transition) down to the low temperatures observed in real clouds of T 5 10 K. We do not yet include magnetic fields or local stellar feedback, deferring these potentially important processes∼ − to future studies. http://www.astro.ufl.edu/~butler85/mbutlerthesis.pdf

52 Massive Star Formation: Theory and Observation

Yichen Zhang

Department of Astronomy, University of Florida, USA Department of Astronomy, Yale University, New Haven, CT 06520, USA Electronic mail: yczhang.astro at gmail.com Ph.D dissertation directed by: Jonathan C. Tan Ph.D degree awarded: May 2013

This thesis is focused on the formation of massive stars, especially trying to answer the question whether they form in a similar way to their low-mass counterparts, i.e., through accretion from gravitationally bound cores (Core Accretion). We make efforts on both theoretical and observational aspects of massive star formation, with the key link being radiation transfer simulations. A model is presented for massive protostars forming from massive dense gas cores that are embedded inside larger −2 star-cluster-forming clumps with high mass surface densities of Σcl = 1 gcm . Such high surface densities may 5 ∼ −4 −3 −1 be needed for a core to collapse in a time scale of 10 yr, reaching accretion rates of 10 10 M⊙ yr to overcome the radiation barrier of massive protostars. Starting with such a highly pressurized core,− we self-consistently calculated the evolution of the protostar, the outflow cavities, and the star-forming efficiency. For a fiducial 60 M⊙ −2 core with Σcl = 1 gcm , we find the final star formation efficiency is gtrsim 0.6. At each particular stage, we self-consistently include the inside-out expansion wave, rotating infall, an accretion disk, and a bipolar magneto- hydrodynamic accretion-powered disk wind. We also add the gas opacities and adiabatic cooling, which are important around massive protostars. Radiation transfer simulations are then carried out for such models. We find the near- facing outflow cavity significantly affects the IR morphology and dominates the mid-IR emission. At 30 - 40 µm, although the outflow cavities are still dominant, lower extinction reveals the fainter far-facing outflow. The dust and gas inside the outflow cavity affect the detailed intensity distribution. We find that the spectral energy distribution (SED) becomes very flat when the system is viewed at an inclination that is near face-on, which may be used to identify such systems. We also find that the colors deduced from the mid-IR to sub-mm SED can be indicators of the evolutionary stages of massive star formation. We carry out observations of an example of a massive protostar, G35.2-0.74, at 30 and 40 µm with SOFIA-FORCAST. We apply the fiducial radiation transfer model to this source and through fitting both the SED and the intensity profile along the outflow axis simultaneously, constrain the properties of the protostar. Excellent fits between the theoretical model and the observational data are achieved, allowing us to estimate the protostellar mass to be 20 - 30 M⊙, the −2 core mass to be 240 M⊙ and the clump mean mass surface density to be 0.4 - 1 g cm . These results indicate this is a indeed a∼ massive protostar forming at the center of a high mass surface density core and clump via relatively ordered collapse, accretion and the driving of powerful outflows. At least in this one example, this is evidence in support of the Core Accretion theory, i.e., that a massive star forms similarly to a low-mass star.

53 New Jobs

Postdoctoral fellowships and PhD position in Star- and planet formation, astrochemistry, and early solar system at Leiden Observatory

Two 3-4 year postdoctoral fellowships and one 4-year PhD position are available within the Molecular Astrophysics group of E.F. van Dishoeck at the Leiden Observatory for observational and modeling studies of star- and planet formation and their astrochemistry. The postdocs and PhD students will be part of an international team studying the physical and chemical evolution from collapsing cores to protoplanetary disks and exoplanets centered around ALMA data. A wide range of complementary data from Herschel as well as ground-based infrared and submillimeter spectroscopy is available. One postdoc position will be focussed on developing models to link the chemical composition of disks with that of icy solar system objects such as comets. The postdoc candidates are expected to co-supervise PhD students and are encouraged to also pursue a personal research program. The postdoc appointments are initially for two years, with the possibility of renewal of 1-2 years. They can start anytime up to Fall 2014. Candidates with an observational and/or modeling background in astrochem- istry, low-mass star formation, circumstellar disks, submillimeter spectroscopy, planet formation and planet population synthesis models are encouraged to apply. Leiden Observatory carries out observational, interpretative and theoretical research in the fields of the star and planet formation, laboratory astrophysics, galactic structure, the formation and dynamics of (high-redshift) galaxies and their nuclei, and cosmology. Leiden is a charming university town, within easy reach of the major European centers. Applications should include a curriculum vitae, publication list, and a brief statement of research experience and interests, and arrange for at least three letters of reference to be uploaded on the relevant website. Review of applications for the postdoc positions will start on November 15 2013. Deadline for the PhD position is December 15 2013. e-mail inquiries: [email protected] Web site for submission: postdocs: http://jobs.strw.leidenuniv.nl/2014/dishoeckPD/ PhD: http://www.strw.leidenuniv.nl/phd/apply.php

Postdoctoral position in star- and planet formation at MPE

A 2-year postdoc position is available at the Max-Planck Institut fur Extraterrestrische Physik in Garching for ob- servational or theoretical studies of star- and planet formation starting in Fall 2014. The postdoc will be part of an international team studying the physical and chemical evolution of young stellar objects and protoplanetary disks using Herschel spectroscopy as well as ground-based infrared and submillimeter data, in particular ALMA. Connec- tions between galactic and extragalactic astrochemistry and star-formation are being pursued as well. The candidate is encouraged to also pursue a personal research program. Extension for a third year may be possible depending on available funding. Applications should include a curriculum vitae, publication list, and a brief statement of research experience and interests, and arrange for at least three letters of reference to be uploaded on the website. Review of applications will start on November 15 2013. e-mail inquiries: [email protected] Web site for submission: http://jobs.strw.leidenuniv.nl/2014/dishoeckPDMPE/

54 Postdoctoral position in Star Formation Theory and Computation

The Department of Astronomy & Astrophysics at the University of California, Santa Cruz (UCSC) invites applications for a postdoctoral position in fluid dynamics code development and numerical modeling of star formation, affiliated with a Theoretical and Computational Astrophysics Network (TCAN) awarded to Mark Krumholz (UC Santa Cruz), Christopher McKee and Richard Klein (UC Berkeley), and Eve Ostriker and Jim Stone (Princeton University). The position is for a total of three years, subject to continued progress each year. The position starts in the summer or fall of 2014. The successful candidate will work closely with other members of the network at Berkeley and Princeton to implement advanced capabilities for multi-scale, multi-physics simulations within the radiation-magneto- hydrodynamics codes Orion and Athena, and use these codes to investigate the formation and evolution of giant molecular clouds, star clusters, and individual stars within the galactic-scale interstellar medium. Candidates should have obtained their Ph.D. in astrophysics or a related discipline by September 30, 2014. Expertise in one or more of the following areas is highly desirable: computational magneto-hydrodynamics, computational radiation-hydrodynamics, theory of star formation and the interstellar medium. Applications should be submitted electronically by December 15, 2013 to receive full consideration. Applications must include a CV, publication list, statement of past research and future interests, and at least three letters of reference. For more details and to apply, visit https://recruit.ucsc.edu/apply/JPF00068

Multidisciplinary PhD in planet formation

The Institute for Astronomy (D-PHYS) and the Institute of Geophysics (D-ERDW) at ETH Zurich invite applications for a new PhD position which will test planet formation theory from an astronomical, cosmochemical, and geophysical perspective. The young Solar System is believed to have been enriched in certain radioactive isotopes that could only be produced by the supernova explosion of a massive star, and the internal energy from the decay of these isotopes has been shown to influence the subsequent formation and evolution of planets. You will use state-of-the-art computer models to determine the typical yield of radioactive isotopes in star forming environments, and the influence of these isotopes for forming planets. The results of this project will be used to assess how common planetary systems like our own may be, which has profound implications for the frequency of life in the Universe. We are looking for a student with a strong background in physics, and in particular astrophysics and/or geophysics. Experience of computer programming is highly desirable, but not a prerequisite. Salaries for PhD students start at CHF 52 500. You will have the opportunity to study experimental and theoretical aspects of astronomy and geophysics through formal coursework, conducting research with local experts in star and planet formation and geophysics, as well as our international network of collaborators, and utilize state-of-the-art facilities. The Institute for Astronomy and the Institute of Geophysics maintain a range of high performance computing options, including stand-alone machines, large clusters, and the resources of the Swiss National Supercomputing Center (CSCS). Members of both institutes also play a leading role in the interdisciplinary PLANET-Z initiative linking research groups at ETH Zurich in astronomy, earth sciences, and computational astrophysics at the University of Zurich. Applications are invited from all nationalities and should consist of a CV, description of relevant research experience, academic transcripts, scores from relevant standardized tests (e.g. TOEFL, Physics GRE) a personal statement of interests and goals, and the names of three references that can be contacted if necessary. The ETH Zurich provides benefits for maternity leave, retirement, accident insurance, and relocation costs, see also http://www.pa.ethz.ch/ Materials should be sent electronically in a single pdf file to [email protected] before December 1st 2013. Review of applications will begin immediately.

55 McLean Postdoctoral Fellowship Exo-Planets, Brown Dwarfs and Young Stars University of Toronto

Applications are invited for a postdoctoral fellowship at the University of Toronto to start in the summer or fall of 2014. The successful candidate, designated as McLean Postdoctoral Fellow, will work with prof. Ray Jayawardhana and his collaborators on observational and analytical studies of extra-solar planets, brown dwarfs and young stars, and will be encouraged to pursue independent research on related topics. On-going and recent projects include photometric and spectroscopic studies of extra-solar planets, high-contrast imaging searches for sub-stellar companions around young stars, investigations of brown dwarf variability and multiplicity, and the SONYC (Substellar Objects in Nearby Young Clusters) ultra-deep survey, using data from VLT, Subaru, Gemini, Keck, CFHT, Kepler and other major observatories. The position is for two years, with extension to a third year possible, and comes with a competitive salary and funds for research expenses. Applicants should send a curriculum vitae, a description of research interests and plans and a list of publications, and should arrange for three letters of recommendation to be sent directly to [email protected]. All materials should be submitted electronically. Applications received before 2013 December 15 will receive full consideration. Early expressions of interest and inquiries are welcome.

Moving ... ??

If you move or your e-mail address changes, please send the editor your new address. If the Newsletter bounces back from an address for three consecutive months, the address is deleted from the mailing list.

56 Meetings

First Announcement ESO Workshop Herbig Ae/Be stars: The missing link in star formation Santiago de Chile, April 7-11, 2014

This is the first announcement for the ESO conference ”Herbig Ae/Be stars: The missing link in star formation” to be held in Santiago de Chile, on April 7-11, 2014. The venue of the meeting will be the ESO Headquarters in Santiago, Chile, located on the ESO/ALMA campus. More detailed information is available on our web page http://www.eso.org/haebe2014.html or by e-mail to [email protected]. We encourage you to circulate the announcement among your colleagues. Scientific organising committee: M. van den Ancker (ESO/Garching) , J.-P. Berger (ESO/Garching), K. Bjorkman (Toledo, US), J. Bouwman (MPIA, D), S. Casassus (Santiago, Cl), C. Dullemond (Heidelberg, D), A. Dutrey (Bordeaux, F), J. Monnier (Michigan, US), R.D. Oudmaijer (Leeds, UK; co-chair), F. Palla (Arcetri, I), L. Testi (ESO/Garching), W.J. de Wit (ESO/Chile; co-chair) GOAL OF THIS WORKSHOP: The ESO workshop on Herbig Ae/Be stars is dedicated to the formation and pre-main sequence evolution of intermediate- mass stars. The stellar masses involved correspond to the transition regime between the formation of solar-type stars and high-mass stars, i.e. the dichotomy between clustered and isolated formation, between disk accretion and magneto- spheric accretion, between convective and radiative stellar interiors, between slow and fast rotators. The disks around HAeBe stars evolve in harmony with planet formation towards debris disks and mature planetary systems. Over the past 20 years, new sensitive instruments have opened up the milli- arcsecond and sub milli-arcsecond spatial scales where the disk physics takes place and planetary formation processes occur. ALMA will complement spatially and advance spectrally at high resolution the connection between the inner disks and the outer, dusty disks as observed by space-based observatories. The workshop aims to charter the evolution of the circumstellar material from the formation phases, during the star’s PMS contraction, and down to the dispersal and/or debris phase. Topics include (i) stellar interior and surface physics (ii) accretion/ejection (iii) disk evolution; (iv) the connection with debris disks and planet formation. The workshop lasts five days and is held at the ESO-Chile headquarters in Santiago. It will have classic format of invited reviews, contributing talks and posters. There will be ample time for discussions, and space for posters. The conference venue has a capacity for 100-120 participants. Financial support is available on request. IMPORTANT DEADLINES: Submission of abstracts: 31 January 2014 Registration: 31 January 2014 CONTACT US: Conference e-mail: [email protected] Webpage: http://www.eso.org/haebe2014

57 Exoplanet Observations with the E-ELT

Exoplanet research is one of the major science drivers for the future 39-m European Extremely Large Telescope (E- ELT). The E-ELT project is organising a community workshop that will explore the science cases as well as selected and planned capabilities of the E-ELT in the field of exoplanets. The purpose of this workshop is to provide a forum to synthesise a vision of the goals to be achieved by the E-ELT in the field of exoplanets, considering on the one hand the planned capabilities of the E-ELT and its instrumentation, and on the other hand, the most relevant issues in exoplanet science of the next decade. The meeting will take place at ESO Garching, Germany, 3-6 February 2014. The registration period is 1 October - 15 November 2013. http://www.eso.org/sci/meetings/2014/exoelt2014.html Electronic mail: exoelt2014 at eso.org

58 Summary of Upcoming Meetings

The Orion Nebula Cluster as a Paradigm for Star Formation 14 - 16 October 2013 STScI, Baltimore, USA http://www.stsci.edu/institute/conference/orion/ Physical Processes in the Interstellar Medium 21 - 25 October 2013 MPE, Garching, Germany http://www.ism-spp.de/conferences/ismsppcon2013/ 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/ Exoplanets and Disks: Their Formation and Diversity II 8 - 12 December 2013, Kona, Hawaii, USA http://exoplanets.astron.s.u-tokyo.ac.jp/SubaruConf13/index.html Exoplanet Observations with the E-ELT 3 - 6 February 2014 Garching, Germany http://www.eso.org/sci/meetings/2014/exoelt2014.html Herbig Ae/Be stars: The missing link in star formation 7 - 11 April 2014 Santiago, Chile http://www.eso.org/haebe2014.html 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 Living Together: Planets, Stellar Binaries and Stars with Planets 8 - 12 September 2014 Litomysl Castle, Litomysl, Czech Republic http://astro.physics.muni.cz/kopal2014/

59 Planet Formation and Evolution 2014 8 - 10 September 2014 Kiel, Germany http://www.astrophysik.uni-kiel.de/kiel2014 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/

Short Announcements

Planet Formation and Evolution 2014

NEW DATE: September 8 - 10, 2014, Kiel, Germany http://www.astrophysik.uni-kiel.de/kiel2014

60