269 — 12 May 2015 Editor: Bo Reipurth (Reipurth@Ifa.Hawaii.Edu) List of Contents

Home , Frank Shu, HD 202628, NGC 7822

THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 269 — 12 May 2015 Editor: Bo Reipurth ([email protected]) List of Contents

The Star Formation Newsletter Interview ...... 3 My Favorite Object ...... 8 Editor: Bo Reipurth [email protected] Perspective ...... 12

Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers ...... 17 [email protected] New Jobs ...... 42 Technical Assistant: Hsi-Wei Yen Meetings ...... 44 [email protected] Summary of Upcoming Meetings ...... 46

Editorial Board Short Announcements ...... 48

Joao Alves Alan Boss Jerome Bouvier Lee Hartmann Cover Picture Thomas Henning Paul Ho The HII region on the cover is known as Sharp- Jes Jorgensen less 171, or W1, or NGC 7822. The young cluster Charles J. Lada Berkeley 59, seen in the upper left corner, contains Thijs Kouwenhoven a group of OB-stars at a distance of∼845 pc. The Michael R. Meyer cluster is sculpting the neutral gas into cometary Ralph Pudritz clouds and elephant trunks. North is left and east Luis Felipe Rodr´ıguez is down in this image. Ewine van Dishoeck Hans Zinnecker Image courtesy Neil Fleming http://flemingastrophotography.com The Star Formation Newsletter is a vehicle for fast distribution of information of interest for astronomers working on star and planet formation and molecular clouds. You can submit material for the following sections: Abstracts of recently accepted papers (only for papers sent to refereed Submitting your abstracts journals), Abstracts of recently accepted major re- views (not standard conference contributions), Dis- Latex macros for submitting abstracts sertation Abstracts (presenting abstracts of new and dissertation abstracts (by e-mail to Ph.D dissertations), Meetings (announcing meet- [email protected]) are appended to ings broadly of interest to the star and planet for- each Call for Abstracts. You can also mation and early solar system community), New submit via the Newsletter web inter- Jobs (advertising jobs specifically aimed towards face at http://www2.ifa.hawaii.edu/star- persons within the areas of the Newsletter), and formation/index.cfm Short Announcements (where you can inform or re- quest information from the community). Addition- ally, the Newsletter brings short overview articles on objects of special interest, physical processes or theoretical results, the early solar system, as well as occasional interviews. Newsletter Archive www.ifa.hawaii.edu/users/reipurth/newsletter.htm tential of a small-amplitude density perturbation, in stars or gas, in a flattened axisymmetric galaxy. The perturba- Frank Shu tions were oscillatory in time and had a m-fold sinusoidal in conversation with Bo Reipurth variation in azimuthal angle, with the radial variation to be determined self-consistently from the joint equations of dynamics for the stars and gas plus Newton’s theory of gravity. These calculations, supervised by Lin’s sure vision that the actual phenomenon had to be quasi-stationary and not transitory, grew to become the foundations of modern spiral density-wave theory. It was pure dumb luck that brought me there for the beginning, but density-wave theory holds a special place in my heart. It is a topic to which I have returned many times in my career, as the ideas turned out to have important applications not only in disk galaxies (e.g., the study of flocculence resulting from the chaos induced by overlapping subharmonic resonances with Greg Laughlin and Sukanya Chakrabarti, and ”feath- ering” as a parasitic instability behind self-gravitating, Q: The Lin-Shu density wave theory for the spiral struc- magnetohydrodynamic spiral shocks with Wing Kit Lee), ture of disk galaxies was published in 1964. What was the but also in planetary rings (resonantly driven, linear and genesis of this enormously influential concept? nonlinear, density waves with Jack Lissauer, Luke Dones, A: The project started when C. C. Lin of MIT spent a sab- Jeff Cuzzi, and Chi Yuan), and in heavy protoplanetary batical year in 1961 at the Institute for Advanced Study disks (e.g., m =1 SLING instability for binary and giant in Princeton, to work with C. N. Yang on the theory of planet formation with Scott Tremaine, Fred Adams, and superfluids. Lin attended a symposium on the spiral struc- Steve Ruden). ture of disk galaxies organized by Bengt Strömgren, who Q: From the linear theory of density wave theory of the was then the Professor of Astrophysics at the IAS. At this stars you began to study the nonlinear theory of the re- meeting, Jan Oort gave the plenary lecture on the wind- sponse of the interstellar medium and its implications for ing dilemma of material spiral arms. Per Olof Lindblad, star formation. What influenced you to change your fo- the son of Bertil Lindblad (for whom Lindblad resonances cus, given that there were major unresolved issues with the are named), presented some early numerical N-body sim- stellar theory? ulations of a system of self-gravitating stars in a flattened geometry. The idealized system exhibited transient spi- A: After getting my PhD from Harvard in 1968, I spent ral patterns that sporadically formed and dissolved. From five years on the faculty at Stony Brook, which was just those two lectures, Lin got the seminal idea that the spiral getting started with a newly formed astronomy group headed patterns were really a wave phenomena, and not material by Steve Strom. From Steve, I learned a lot about stars arms. as points of light and not just as points of mass. I had become interested in the problem of OB star formation When Lin returned to MIT, he started to organize a team behind the two-armed shockwave patterns in spiral galax- of young theorists to help him develop this idea. The ies and was collaborating with Chi Yuan and Bill Roberts group grew eventually to include Alar Toomre, Chris Hunter,for a better astrophysical understanding of the triggering Chi Yuan, Bill Roberts, James Mark, Y. Y. Lau, and mechanism. It soon became clear that we had to have Guiseppe Bertin. I was then a MIT physics undergraduate a much better model for the interstellar medium than major, uncertain about how to have a career in science. the adopted default of a single-phase isothermal gas, so Lin hired me as a summer research assistant to help him I went to Berkeley on a one-semester sabbatical to learn perform some numerical calculations on the problem of about the elegant two-phase model that had been devel- wind-driven ocean circulation, another scientific problem oped by George Field, Don Goldsmith, and Harm Habing. that interested him at the time. After spending a sum- Together with Vinny Milione, Don Goldsmith (whom I mer crunching numbers on an old mechanical calculator, helped later to recruit to Stony Brook), Chi Yuan, Bill I managed to finish the assigned calculations well enough Gebel, and Bill Roberts, we wrote a paper that dealt with that Lin agreed to be my adviser for the senior thesis that the problems of phase transformations and star formation all MIT physics students had to write before graduation. in a two-phase ISM periodically exposed to shockwaves in This thesis was on density wave theory, and my primary a spiral galaxy. job was to calculate asymptotically the gravitational po-

3 This work drew the interest of Ron Allen, who then headed papers on the subject of mass transfer in semi-detached a radio group at Groningen building 21cm-line receivers binaries that are still considered benchmarks in the field. for the newly commissioned Westerbork Radio Synthesis From semi-detached binaries to contact binaries was a Telescope. Ron wanted to learn how WRST might be used small step seemingly. But in semi-detached binaries, all to test density wave theory in the context of the response the action is at the surface or outside the stars and can of the interstellar medium, and he came to MIT (where be observed. In contact binaries, all the important ac- I was visiting) to question C. C. Lin and me about this tion is inside the stars, or within a common envelope, and problem. Ron later asked me to go for an extended visit cannot be observed (or so we thought). A naive idea for at Groningen, an invitation that I accepted in the summer the structure of contact binaries is simply to jam two sin- of 1973. It was the first time that my wife Helen and I gle stars together. This idea leads to the conclusion that had spent appreciable time living in Europe, a wonderful two main-sequence stars cannot form a co-rotating con- experience that we both still cherish. It was also a valu- tact binary because their mass-radius relationships on the able learning opportunity for me, as a theorist, to interact main-sequence are inappropriate for them both to fill their closely with radio astronomers of the caliber of Ron Allen, Roche lobes except in the single case of equal-mass compo- Ron Ekers, Miller Goss, and Renzo Sancisi, who were all nents. Observationally, W Ursa Majoris stars constitute at Groningen at the time. They taught me up close the the most common form of close binary systems; the two value of checking beautiful theoretical ideas with the hard components are undoubtedly both on the main-sequence; empirical facts from observations. they are co-rotating; yet no W UMa system is known that Q From density wave theory of the interstellar medium, has equal mass components! Clearly, the naive theory is you then began to study the internal structure of contact inadequate, and some drastic new ingredient needs to be binaries. What initiated such a major change of research added. Leon Lucy and others turned out to have very dif- direction? ferent thoughts on what drastic new idea was needed than The change was triggered by my move to Berkeley. While Steve Lubow and I. These differences led to enormous con- I was there on sabbatical in Fall 1971, George Field an- troversy, not between Lucy and us, but with peripheral nounced that he was moving to Cambridge, Masssachusetts critics on the scene, that has not been settled even today. to head the joint astronomy effort at Harvard and the Lawrence Anderson (who then had an office next to mine), Smithsonian Astrophysical Observatory. The revamped Mal Raff, and I developed a technique of Doppler imaging organization changed its name to the Center for Astro- of W UMa stars that we never followed up after our ini- physics under his leadership. The contacts I had made tial observational data taken at Lick Observatory because in the Berkeley Astronomy department encouraged me to moving starspots badly contaminated the spectral shape apply for the position vacated by Field’s departure. I suc- of a line that should have ideally reproduced the spatial ceeded in the application, and in the Fall of 1973, after shape of a uniformly rotating dumbbell. Had I been in spending the summer in Groningen, Helen and I drove the mood to think more calmly at the time, I might have across the USA to begin our new life at Berkeley. realized that the technique offered a chance to view the My first PhD student there was Steve Lubow, a student differential internal circulation that we had postulated to of the Physics Department at Berkeley, and he wanted to be at the heart of the resolution of the problem, but that work on a clean problem that could make use of his ample seemed inaccessible to observation. Somebody needs to mathematical abilities. At the time, interacting binary revisit this problem and technique, which I liken to be- stars were the rage because of the tremendous discovering related to the theory of single stars in the same way ies being made by X-ray telescopes launched into space. that diatomic molecules are related to the theory of single So we looked into the problem of interacting binaries and atoms. In astronomy, we have a well-established theory of discovered a pioneering paper by Gerald Kuiper published single atoms, but none for diatomic molecules. in 1941 on the problem of mass-transfer in semi-detached Q: In 1977 you published your study on self-similar col- binaries. Kuiper’s analysis invoked particle trajectories to lapse of isothermal spheres. This was again a major change do the dynamical calculations and may have been over- of subject. From where came your interest in protostars? looked for that reason since the mass-transfer rates are so A: The impetus came from two different directions. First, large that collisions among the individual atoms making I had always been interested in how stars formed in the up the mass-transfer stream must be important. My ex- context of OB stars being the delineators of optical and perience in stellar dynamics and gas dynamics taught me UV spiral structure in disk galaxies. Second, by 1977, I the differences and similarities between collisionless and was very upset by the tone of the debate on contact bina- collisional systems, which was a perfect match with Steve ries. When I complained about the unpleasant situation Lubow’s expertise in doing perturbational calculations us- privately to Steve Strom and Bart Bok in a visit to Kitt ing asymptotic methods. In 1975 and 1976, we wrote two Peak, both of them, separately and independently, advised

4 me to switch fields – to the subject of star formation, not but because Roman numerals do not have a zero. That from the point of view of the interstellar medium, but was an invention of Indian and Chinese mathematicians!) from the point of view of the actual objects. Since Bok Q: In 1987, you and Fred Adams and Susana Lizano pub- and Strom were my lifelong friends and mentors, I took lished an ARAA review on star formation in molecular their suggestions seriously and began to study in earnest clouds. With about 2000 citations, this is one of the most the literature on protostars. influential articles ever in the field of star formation. What I knew about the controversy between Hayashi and Larson accounts for this profound impact? concerning where pre-main-sequence stars would appear A: My guess is that the article satisfied a need from both in the H-R diagram after a phase of rapid gravitational 5 observers and theorists to have a comprehensive discussion collapse lasting on the order of 10 yr, but it was not that unified what had previously been regarded as distinct until I found the papers by Larson and Penston on self- subfields. Fred, Susana, and I synthesized the work done similar collapse that I saw a way in which I might make at Berkeley (which included the optical/infrared observa- a contribution to the problem. The L-P solutions, ap- tions of Len Kuhi, Gibor Basri, and Martin Cohen, as plied to gravitational collapse, correspond to states that well as the radio work of Jack Welch, Dick Plambeck, Mel are initially far from equilibrium. For example, they had Wright, and Carl Heiles), together with the rich variety supersonic inflow toward the center at infinity. I could of work done at the Center for Star Formation Studies not imagine how such a state could be set up by natural that included UC Santa Cruz and NASA Ames (with too processes occurring in the ISM (but later, Susana Lizano, many names to mention individually), and other organi- Daniele Galli, Jorge Cantó, and I found a way to use re- zations (such as by the strong star formation group at the versed L-P solutions for modeling the champagne flows of CfA). Rightly or wrongly, we offered a rational organizing H II regions). On the other hand, I knew from our work framework that (a) linked the theory and observations, using Bonnor-Ebert spheres and their cousins in the two- and (b) gave an outline of future directions where addi- phase model of the ISM that such objects became singular tional progress might be made. The most important con- isothermal spheres in the limit of high central concentra- cept that we put forward in a single cartoon is the idea tion. Thus, I was motivated to study the problem of how that star formation occurs in four stages: a first stage that an unstable equilibrium starting with a singular isother- involves the formation of molecular cloud cores (e.g., My- mal sphere would gravitationally collapse. To my delight, ers and Benson); a second stage that involves the gravita- the inside-out collapse is exactly self-similar without hav- tional collapse of an unstable, slowly rotating, core to form ing to assume self-similarity as a hypothesis, and the cen- a protostar, an infalling envelope, and a centrifugally sup- tral product is a point that had a mass which grew linearly ported circumstellar disk (e.g., Sargent and Beckwith); a with time! By then, I had enough experience as a real as- third stage in which the infall would be reversed by a bipo- tronomer to realize it was important to compute also how lar outflow (e.g., Snell, Loren, and Plambeck or Rodr´ıguez, much light such a point would generate as a protostar. Ho, and Moran); followed by a fourth stage in which a pre- This became the starting point of my studies with Steve main-sequence star emerges surrounded by a circumstellar Stahler and Ron Taam that led to a satisfactory resolu- disk that might give birth to a planetary system. tion of the controversy between Hayashi and Larson, in agreement with contemporaneous numerical simulations Although we were criticized at the time for focusing on by Winkler and Newman. the problem of the formation of single stars (mostly of low mass), and not discussing much the issue of the formation The self-similar collapse of singular isothermal spheres was of binary or multiple stars or clusters, nor emphasizing also the beginning of a long series of fun generalizations the importance of interstellar turbulence, I still think we that allowed us to find analytical or semi-analytical solu- made the right decision. Concrete progress in science is tions when we added rotation (with Susan Terebey and not made by attacking all important problems simultane- Pat Cassen), departures from axial symmetry (Daniele ously: for example in quantum mechanics, one must learn Galli and Susana Lizano), magnetic fields (Zhi-Yun Li to solve the hydrogen atom, and then one can move to and then Fred Adams), combined rotation and magnetic diatomic molecules, triatomic molecules, and eventually fields (Tony Allen, Zhi-Yun Li, Daniele Galli, and Susana DNA. Lizano), and general relativity (Mike Cai). Looking at the implied spectral energy distributions of the corresponding Q: In the nineties you and your collaborators developed collapsing objects led Fred Adams, Charlie Lada, and me a detailed theory of the magnetocentrifugally driven flows to our classification of Class I, II, and III objects based from a young magnetized star and its accretion disk, which on the appearance of their SEDs. (Later Phillipe André has had a major influence on the way we understand young and his colleagues added a Class 0, to which I objected stars and their mass loss. How did this concept develop? not so much because it is not a valid scientific addition, A: Again, it was a matter of paying attention to what the

5 observers were saying, and then sieving through the dif- A: The study of chondrules and calcium-aluminum-rich ferent ideas put forward by theorists, without being preju- inclusions (CAIs) came from another old scientific friend- diced by the motivation to explain the most striking obser- ship: this time with Typhoon Lee, the discoverer, with vational fact, which were frankly the beautiful images that Jerry Wasserburg, of Al-26 in the Allende meteorite. Ty- you, Hans Zinnecker, and others were making of jets from phoon was the person who persuaded me to help bring YSOs and their associated, rapidly moving, Herbig-Haro astronomy to a higher level in Taiwan, and I helped to objects. For my own part, I have always preferred mo- persuade other Chinese-American astronomers including tivation by fundamental theoretical issues to being over- Chi Yuan, Fred Lo, Paul Ho, Sun Kwok, Ron Taam, You- influenced at the start by observational data. From the Hua Chu, and many others to lead this effort and make start of discussions of pioneers in the field like Lyman it a success. But the founding and nurturing of ASIAA is Spitzer and Leon Mestel, these issues have concerned the another story. obstacles to star formation presented by rotation and mag- Carbonaceous chondrites like Allende are a curious mix- netic fields. ture of a grainy matrix that has never experienced tem- While rotation by itself could and would give rise to pro- peratures higher than 600 K if we are to judge from the tostellar disks, it cannot solve the angular momentum fragile organic molecules that they contain, and inclusions problem of the central object. Processes like spiral den- like chondrules and CAIs that have undergone conditions sity waves might help transport angular momentum in the hot enough to melt rock (i.e., 2000 K or more). Yet such outer disk, but they become ineffective in the central re- meteorites are supposed to originate from parent bodies in gions. In these regions, it almost certainly must be mag- the asteroid belt, which astronomical models and obser- netic fields, combined with rotation, that would give rise vations suggest should never have had temperatures that to the bipolar outflows that act as the process by which can melt rock. CAIs also contain extinct radioactivities protostars reveal themselves as optically visible objects. like Al-26 that are surely telling us something important The efficacy of the combination of strong magnetic fields about the early solar system, information that we have no coupled with rapid rotation for producing massive out- way of accessing by remote astronomical observations. flows was realized by early workers like Lee Hartmann and Typhoon Lee, Sienny Shang, Al Glassgold, Mathieu Gounelle, Keith MacGregor building on work by Leon Mestel con- Ernest Rehm, and I had the simple idea that the curious cerning mass loss from rotating magnetized stars, or Ralph mixture of hot and cold rocks may literally be a mixture Pudritz and Colin Norman building on the work of Roger beginning with hot rocks from the interior of the primi- Blandford and David Payne on extragalactic radio jets. tive solar nebula flung out to large distances by an X-wind As a byproduct, we conjectured that the outflow process responsible for an ancient bipolar outflow in the solar sys- would help a star to define its own mass – another theo- tem. The entrained material would undergo aerodynamic retical conundrum since molecular clouds and even their size sorting in flight, with mm-sized and larger objects cores do not have stellar masses as a natural characteristic landing typically in the asteroid belt, where they would mass scale. seed the cold matrix of protoplanetary dust already there Once one has this motivation, discovering the right set with a sprinkling of chondrules and CAIs (which can make of equations to solve is relatively easy (in fact, a litera- up a major portion of the total mass of chondritic mete- ture search showed that the appropriate formulation had orites). If this were the case, then we need not invent other already been given by a physics MIT professor, Stan Ol- exotic mechanisms that would modify or completely dam- bert, who taught me E&M), and then it was just a matter age current promising ideas about how the parent bodies of time to find a way to solve the posed problem in a com- of chondiritc meteorites, i.e., planetesimals, originate (e.g., pletely satisfactory way (which took ten years, and the work by Andrew Youdin and collaborators). help of five graduate students – Joan Najita, Eve Ostriker, To minimize the number of adjustable parameters in this Sienny Shang, Mike Cai, and Subu Mohanty). theory, we tried to explain the wild variety of extinct ra- In the meantime, we discovered that by considering the dioactivities – Al-26, Mn-53, Ca-41, Be-10, etc., that one heating and cooling of such outflows, a subject on which finds in the CAIs of carbonaceous chondrites as products we had the help of Steve Ruden and Al Glassgold, we got of irradiation by ancient solar flares before such material as a gratifying bonus the (seemingly) highly collimated, became entrained and flung out to interplanetary (and in- pencil-beam jets that you and others were, rightly, so ex- terstellar) distances by the X-wind. This effort had mixed cited about! success (to make a bad pun), as we admitted in our papers. Q: More recently your interest turned to chondrules. Do However, we did make a spectacularly successful predic- studies of present-day star formation and of the distant tion, which is that cometary material, which was then formation of the solar system illuminate each other? thought to be pristine, when collected and brought back to Earth, should also contain chondrules and CAIs, but of

6 smaller sizes. This prediction was borne out by the anal- always thought that science and technology would rise to ysis of Kevin McKeegan (who discovered Be-10 in CAIs) the two connected challenges and solve the problem before of the dust samples returned by the Stardust mission to it got really bad. Three to four decades passed, and the Comet Wild. Kevin has also analyzed the oxygen isotopic problem is still not close to being solved. ratios of an O-16/O-17/O-18 sample in the solar wind re- As a senior scientist with some influence in Taiwan, I fi- turned by the Genesis mission. They are in accord with nally felt that I had a social responsibility to not only Robert Clayton’s prediction that if X-wind theory is cor- give advice, but to roll up my sleeves and try to help rect, these ratios should be what are found in CAIs (which find practical solutions. Thus, I retired from the Univer- had previously been considered ”anomalous”) and not as sity of California in 2009 and started a research group they are found on the Earth (which had previously been using high-temperature molten salts to advance two tech- considered ”normal”). These successful predictions do not nologies: supertorrefaction and thorium breeder reactors. ”prove” that the origin of CAIs and chondrules by X-wind (Videos of our projects on ”biochar” and ”modular tho- transport is true, merely that the idea has been tested by rium reactors” can be found on the YouTube website of serious scientists and not found to be false. ”Raw Science”.) With biochar produced at rates achiev- Q: In addition to your research you have written several able with supertorrefaction using waste biomass resources textbooks, the undergraduate text book ’The Physical Uni- that do not impact on food production, we estimate that verse’ and the two-volume graduate textbook ’The Physics it should be possible to reverse climate change in about 40 of Astrophysics’. What motivated such a major undertak- years (i.e., get CO2 concentrations in the atmosphere back ing? down to 350 ppm). However, this reversal is possible only A: I have always liked teaching, and I have always con- after other technologies bring the net CO2 emission from tended that there are really only two ways to learn a sub- all primary sources of energy generation down to zero. ject well: one is to do research in it; the other is to teach To help reach the target of zero emissions, many peo- it. So I have always regarded teaching not as an unwanted ple (including James Hansen and Bill Gates) believe that chore, but as an opportunity to learn about exciting de- safer, superior (in cost), securer (in terms of weapons velopments in subjects apart from my personal research proliferation), and sustainable forms of nuclear power interests. I have also always enjoyed writing, so written need to be developed and deployed. I am betting my last exposition comes naturally and quickly for me. Writing hurrah in scientific research that molten salt breeder reac- the ”Physical Universe” took two years (in the days when tors that run on the thorium cycle can be that reactor. a tremendous innovation was the invention of electric type- When I feel confident that these two projects can reach writers that had balls with which one could type Greek successful completion without my continued active partic- letters). Most of the two years, apart from tending my ipation, perhaps I can really retire and finish writing ”The normal duties as a Berkeley professor, was spent mak- Story of Astronomy.” ing revisions by the literal method of ”cut and paste.” When word processors became available on personal com- puters, it took me only one year to write the two-volumes of ”The Physics of Astrophysics.” But part of this efficiency derived from my always keeping complete written notes whenever I taught such courses at Stony Brook and Berkeley. I have now retired three times (from Berkeley, from Tsing Hua, and from UC San Diego); if I ever retire permanently, I will go back to writing textbooks. I have two-thirds of a book written entitled ”The Story of Astronomy” that I am itching to finish when I free up some time from more urgent tasks. Q: Upon retirement from the University of California you have devoted your time to studying a range of energy issues in Taiwan. What are your goals? A: My generation of scientists has been acutely aware of the global energy problem since the first Oil Crisis of 1973. And since 1982, I have had a growing concern about the threat posed to civilization by climate change. However, I

7 any known time since its outburst around 1955” (Jones 2008). This brought EX Lup into the center of attention My Favorite Object and the subject of many different kinds of observations, us- EX Lupi ing the most modern instrumentation. It literally became a laboratory where the accretion process in a young stellar Agnes´ Kóspál object could be studied with exceptional clarity. In the following I will summarize what we learned about EX Lup, mostly based on those 10+ papers (and still counting), partly from our group, that has been published since.

2.1 The quiescent system

EX Lup is a young (1-3 Myr) low-mass (<0.6 M⊙) M0V- type star (Gras-Velázquez & Ray 2005), with a quiescent bolometric luminosity of 0.7 L⊙. Its infrared excess above the stellar photosphere indicates the presence of circumstellar material. Sipos et al. (2009) modeled the spectral energy distribution (SED) by a modestly flaring disk with a total mass of 0.025M⊙ and an outer radius of 150au. Interestingly, the inner radius of the dust disk (0.2 au) 1 Episodic Accretion is significantly larger than the dust sublimation radius (0.05 au). There is no hint for any envelope around the system. In quiescence the optical-infrared brightness of The inherent variability of pre-main sequence stars may the source is slightly variable on a few days timescale, have multiple reasons, including time dependent mass ac- with an amplitude less than 0.3 mag. The typical rate of cretion from the disk. There are young stars which exhibit accretion from the disk to the star is very low, on the order extreme, 1–3 orders of magnitude changes in the accre- −10 of a few times 10 M⊙. tion rate, manifesting in sudden brightenings or “eruptions” (Herbig 1977). My favourite object, EX Lup, is These results suggest that on a large scale the quiescent the prototype of one of the two classes of young erup- EX Lup system resembles normal T Tauri stars, except tive stars (Fig. 1). EXors, named after EX Lup, show for its relatively large inner hole and low accretion rate, outbursts often reaching 5-6 mag at optical wavelengths, typically displayed by more evolved disks. However, the although the increasing flux can be observed in the whole innermost part of the system, the heart of the accretion optical–infrared domain. The eruptions typically last a process, seems unusual: the optical spectrum of EX Lup is few months, and are repetitive on timescales from a few unusually rich in emission lines, including permitted emis- years to several decades (Herbig 2007). In many respects, sion lines typical of accreting T Tauri stars, and a large these events resemble more the powerful outbursts of the number of metallic lines which dominate the spectrum in FU Orionis-type stars (FUors) than the continuous bright- outburst (Kóspál et al. 2008, Sicilia-Aguilar et al. 2012). ness fluctuations of even the most active T Tauri stars, and it is believed that some kind of instability is needed to explain the transitition from the low to the high accretion state.

2 The large outburst in 2008

After a large 5mag ﬂare-up in 1955-56, EX Lup had been mostly quiescent with smaller (1-1.5 mag) irregular activity periods until 2008, when it went into outburst again. A new eruption was discovered by Albert Jones, an amateur astronomer from New Zealand, who made thousands of visual brightness estimates of EX Lup (among other stars) Figure 1: Artist’s impression of the EX Lup system. between 1954 and 2010. He published an Astronomer’s Credit: NASA/JPL-Caltech/T. Pyle (SSC). Telegram stating that EX Lup became “brighter than at

8 2.2 Accretion variability umn that suffers velocity variations along the line-of-sight on timescales of days. Assuming Keplerian rotation, the Every few years the quiescent phase is irregularly inter- emitting region would be located at ∼0.1–0.2 au, consis- rupted by activity periods, when EX Lup brightens by tent with the location of the inner disk rim. The near- 1–1.5 mag (e.g., in 1993–1994, Lehmann et al., 1995; or infrared hydrogen lines display a strong spectro-astrometric the four smaller flare-ups between 1995 and 2005, Her- signal, also suggesting a funnel flow or disk wind origin big 2007). In these periods the photospheric spectrum is rather than an equatorial boundary layer. veiled by a hot continuum, inverse P Cygni absorption The picture emerging from the spectroscopic observations, components displaced by several hundreds of km s−1 ap- both in quiescence and in outburst, is broadly consistent pear at the higher Balmer lines, the emission-line structure with the standard magnetospheric accretion model usually undergo striking variations, and many emission lines ex- assumed for normally accreting T Tauri stars. The rapid hibit narrow and broad line profile components. These recovery of the system after the outburst and the similarity signatures indicate intermittent mass infall in magneto- between the pre-outburst and post-outburst states suggest spheric accretion events. that the geometry of the accretion channels did not change Less frequently, EX Lup produces exceptionally power- between quiescence and outburst, only the accretion rate ful eruptions, like its historically largest outburst in 2008, varied (Sicilia-Aguilar et al. 2012). when it brightened by a factor of ∼100 in visual light. The In a magnetospheric accretion scenario, the infalling mate- source reached a peak brightness of V = 8mag in about rial reaches the star in hot spots. Indeed, based on the ex- four weeks, slowly decayed in the high state for six months tensive coverage of the outburst by ESO instruments and with some quasi-periodic oscillations, and returned to the the Spitzer Space Telescope, Juhász et al. (2012) compiled initial state within a few weeks (Fig. 2). In outburst, the −7 an outburst SED, and identified a hot single-temperature accretion rate rose to a few times 10 M⊙, three orders of blackbody component which emitted 80%–100% of the to- magnitude higher than in quiescence (Juhász et al. 2012). tal accretion luminosity. In the X-ray regime, Teets et al. (2012) found a strong correlation between the decreasing optical and X-ray fluxes, obtained by Chandra, suggesting that these declines are the result of decreasing accretion rate. Using XMM-Newton, Grosso et al. (2010) identified a soft X-ray spectral component that is most likely associated with accretion shocks. They also observed UV emission reminiscent of accretion events evi- dently dominated by emission from accretion hot spots.

2.4 The physics of the outburst

The 2008 outburst also provided new insight into the physics of the outburst. Interestingly, no dedicated outburst mod- Figure 2: Visual light curve of EX Lup based on Juhász els exist for EXors in the literature. Commonly, scenar- et al. (2012) showing the extreme outburst in 2008. ios developed for the more powerful FUor eruptions are invoked, such as viscous-thermal instabilities in the disk (Bell & Lin 1994), a combination of gravitational and magneto-rotational instability (Armitage et al. 2001), or 2.3 Magnetospheric accretion accretion of clumps in a gravitationally fragmenting disk (Vorobyov & Basu 2010, 2015). Yet another type of theory The modeling of the quiescent data indicated an inner hole involves a close stellar or sub-stellar companion that per- in the optically thick disk within 0.2–0.3 au. This result turbs the disk and triggers the onset of the enhanced accre- excludes accretion proceeding through an equatorial accretion (Lodato & Clarke 2004; Bonnell & Bastien 1992). An- tion disk that approaches the stellar surface in a bound- other model proposes that accretion onto a strongly mag- ary layer. In outburst, the optical and near-infrared spec- netic protostar is inherently episodic if the disk is trun- tra revealed strong permitted emission lines, and metallic cated close to the corotation radius (D’Angelo & Spruit lines (Sicilia-Aguilar et al. 2012; Kóspál et al. 2011). The 2010). dynamics of the broad component of the emission line Decomposing the profiles of CO fundamental emission lines, profiles suggested that they originate in a hot (6500 K), Goto et al. (2011) separated the profiles of the fundamen- dense, non-axisymmetric, and non-uniform accretion col- tal emission lines into narrow (FWHM ≈ 50kms−1) and

9 boad (FWZI ≈ 150kms−1) components. While the for- episodic crystallization provides a new scenario to produce mer is mostly constant in time and traces cool gas at a the building material for primitive comets. characteristic radius of 0.4 au, the latter decays with time, Motivated by the discovery of episodic crystallization, Ban- and is emitted by hot gas orbiting the star at 0.04–0.4 au, zatti et al. (2012) looked for chemical changes possibly clearly associated with the outburst event (Fig. 3). This induced by the outburst, using archival Spitzer spectra region largely overlaps with the optically thin, dust-free, before and during the 2008 outburst. They found remark- but obviously gas-rich inner part of the circumstellar disk. able changes: the H2O and OH line fluxes increased, new This result lends support to theories where the outburst is OH, H2, and HI transitions were detected, and organics confined to the innermost 0.4 au, without the involvement were no longer seen. These results demonstrate that the of the outer disk. outburst affected not only the surface mineralogy, but also Juhász et al. (2012) also concluded, based on arguments the chemistry in the inner disk. involving the viscous timescale in the disk, that all material accreted in the 2008 outburst should have been located within 0.1 au from the central star. However, while the triggering mechanism is probably related to accretion, it is unlikely that thermal instability, the most widely accepted model of FUor outbursts, triggered EX Lup’s flare-up.

Figure 3: Schematic representation of the broad- and the Figure 4: The spectrum of EX Lup in 2005 (left) and in narrow-line emitting regions from Goto et al. (2011). 2008 (right), based on Abrahám´ et al. (2009). The vertical blue dash at 9.7 µm corresponds to the peak of wavelength of the amorphous silicate profile. Peak wavelengths of forsterite at 10.0 and 11.2 µm are marked by red dashes. 2.5 Effects of the outburst on the circum- The grey curve displays the emissivity of pure forsterite. stellar environment

The 2008 eruption of EX Lup provided direct evidences that the outburst had a strong impact on the circumstellar 2.6 Brown dwarf companion or accretion environment. Abrahám´ et al. (2009) studied Spitzer spec- columns? troscopy, obtained close to peak brightness, and discovered mid-infrared features in the outburst spectrum that were An interesting result arose from a five-year radial velocity not present in quiescence (Fig. 4). These features could survey of EX Lup, collecting 54 observations with HARPS be attributed to crystalline forsterite, and we suggested and FEROS (Kóspál et al. 2014). We found that the ra- that the crystals were produced through thermal anneal- dial velocity of EX Lup is periodic (P = 7.417 d), with sta- − ing in the surface layer of the inner disk by heat from the ble period, semi-amplitude (2.2 km s 1), and phase over at outburst. least four years of observations. This period is not present in any of the usually invoked activity indicators. The ob- Juhász et al. (2012) presented additional multi-epoch Spitzer served absorption line radial velocities can be fitted with spectra, and showed that the strength of the crystalline a Keplerian solution around a 0.6 M⊙ central star with m bands between 8 and 30 µm increased right after the end of sin i = (14.7 ± 0.7) M and eccentricity of e = 0.24 the outburst, but six months later the crystallinity in the Jup (Fig. 5). No classical cold or hot stellar spot can explain 10 µm silicate feature complex decreased. Modeling the the observations (they would predict too high photomet- mid-infrared spectral evolution of EX Lup showed that, ric variability). If confirmed, the companion’s mass would although vertical mixing in the disk would be a poten- fall into the brown dwarf desert, which, together with the tial explanation, fast radial transport of crystals (e.g., by unusually small separation of 0.06 au would make EX Lup a stellar/disk wind) was required. These results demon- a unique binary system, with interesting implications on strate that part of the material irradiated and processed the physical mechanisms responsible for triggering the out- by the outburst found its way to the outer disk. Thus,

10 burst. but in 2005 there were no crystalline signatures in the Interestingly, the emission lines of EX Lup also show a mid-infrared spectrum. The disappearance of the crystals periodic signature with the same period. This suggests may indicate vertical mixing in the disk bringing up fresh very stable accretion columns, and the rotational modula- unprocessed material to the surface, and/or radial trans- tion of the emission lines originating close to the accretion port outward. Following the temporal changes of the crys- shock above the stellar surface. Constructing a model that talline features during the next years/decades will provide would satisfactorily explain the radial velocity variations otherwise inaccessible dynamical information on the disk. of both the absorption and emission lines, either with or How a perturbed system relaxes to equilibrium speciﬁes without a companion, is under way (Sicilia-Aguilar et al., the timescales of the relevant physical processes. A de- submitted). tailed theoretical investigation of the 2008 outburst may also be a milestone in understanding the physics of the eruptive phenomenon. Due to the focused campaigns us- 6 2007-2 (absorption lines) 2009-1 ing many top instruments, the 2008 outburst is probably 4 2009-2 2010-1 the best documented one in history, and thus oﬀers the

] 2010-2 -1 2 2011-1 highest chance to discriminate among the possible physi- 2012-2 0 cal scenarios and the relative importance of diﬀerent kinds

RV [kms of instabilities in the process. -2 FEROS I believe that while astronomy extensively uses a statisti- -4 HARPS

] cal approach, very detailed studies of individual objects, -1 1 especially the prototypes of certain classes of objects, is 0 -1 another promising way towards a thorough understand- O-C [kms ing of the physics in question. EX Lup is an exceptional (emission lines)

] object, and its future observations may still provide break-

-1 2 throughs in understanding the eruptive phenomenon. The 0 [kms only sad point is that we cannot rely on the late Albert em -2 RV Jones to announce the next large outburst. I know that he was proud to have discovered both large eruptions of 0.0 0.5 1.0 1.5 2.0 Phase EX Lup, in 1955 and 2008, and I would like to acknowl- edge here his memorable contribution to the work on my Figure 5: Best Keplerian fit to the absorption line radial favourite object. I would like to thank the efforts of all my velocities of EX Lup. The different colors indicate different EX Lup-enthusiast collaborators as well: it has been and observing seasons. The middle panels shows the residuals, still is a pleasure to work with you. Acknowledgement is while the bottom panel displays the radial velocity of the due also to the support by the Momentum grant of the emission lines. MTA CSFK Lendület Disk Research Group. References: Abrahám´ et al. 2009, Nature, 459, 224 Armitage et al. 2001, MNRAS, 324, 705 Banzatti et al. 2012, ApJ, 745, 90 3 Outlook Bell & Lin 1994, ApJ, 427, 987 Bonnell & Bastien 1992, ApJ, 401, L31 D’Andelo & Spruit 2010, MNRAS, 406, 1208 The eruptive phenomenon in young stars is a fundamental Goto et al. 2011, ApJ 728, 5 process during star formation. At the earliest phases, it Gras-Velázquez & Ray 2005, A&A, 443, 541 helps building up the final mass of the star, and offers a Grosso et al. 2010, A&A, 522, 56 Herbig 1977, ApJ, 217, 693 possible solution for the luminosity problem of protostars Herbig 2007, AJ, 133, 2679 as well. At later phases, when EXor outbursts possibly Jones 2008, CBET, 1217, 1 have a dominant role, the eruptions have a marked ef- Juhász et al. 2012, ApJ 744, 118 Kóspál et al. 2008, IBVS, 5819, 1 fect on the inner disk properties, strongly influencing the Kóspál et al. 2011, ApJ 736, 72 initial conditions for the formation of terrestrial planets. Kóspál et al. 2014, A&A, 561, A61 The 2008 outburst of EX Lup provided a pioneering ex- Lehmann et al. 1995, A&A, 300, L9 periment in this field. Lodato & Clarke 2004, MNRAS, 353, 841 Sicilia-Aguilar et al. 2012, A&A, 544, A93 The freshly created silicate crystals could be used as trac- Sipos et al. 2009, A&A, 507, 881 ers of vertical and radial motions in the disk. In 1955–56 Teets et al. 2012, ApJ, 760, 89 Vorobyov & Basu, 2010, ApJ, 719, 1896 EX Lup underwent an outburst of similar strength and Vorobyov & Basu, 2015, arXiv:1503.07888 likely produced a similar amount of crystals than in 2008,

11 and most recently, AKARI. The dominant technique is infrared absorption spectroscopy toward both young stars as Perspective well as Galactic background stars located far behind the cloud material of interest (Oberg¨ et al. 2011). A typi- The role of ices in star and cal mid-infrared spectrum of ices in a protostellar enve- planet formation lope is shown in Figure 1. Additional, indirect information has been obtained using rotational spectroscopy of Klaus Pontoppidan organics in protostars, thought to trace evaporating ices. Boogert, Gerakines & Whittet (2015) present a comprehensive review of observations of interstellar ices. In the mid- to late 90s, the Infrared Space Observatory offered the first detailed look at ices covering nearly the full relevant wavelength range, but only for the brightest, mostly massive young stellar objects. This was followed by less biased ground-based surveys of water and CO ices in the 3-5 µm region, and then by a treasure trove of Spitzer spectroscopy in the 5–37 µm region, albeit at relatively low spectral resolution that did not fully resolve all ice features. Yet, the study of interstellar ices is not naturally pop- ular within the broad astronomical community. Some may think of it as a somewhat esoteric endeavor with few implications for general astrophysics. Figure 2 shows the rates of astronomy publications on ices, created using Interstellar ices: Esoteric or fundamental? ADS Labs. Two different rates are shown. One searching for papers on observations of ices, combining ice key- I have always thought that ices in inter- and circumstellar words with names of observatories and instruments with environments were incredibly fascinating. Astrophysical mid-infrared spectroscopic capabilities. The other shows ices is a microworld that incorporates disciplines not often studies of interstellar ices using models and laboratory associated with astronomy, including surface chemistry experiments. Only a couple of hundred refereed papers and material sciences. In dense, cold molecular clouds, as have ever been produced on observations of ices. They well as in protostellar envelopes much, or even most, of the peaked during and immediately after the ESA Infrared carbon, oxygen and nitrogen are frozen on refractory dust Space Observatory mission, although Spitzer maintained grains as simple, volatile molecules. The most abundant a steady rate of observational publications of roughly 7 a species are generally water, CO2 and CO, but a greater year until 2013. In contrast, publications using theoretical number of various organics are also known. Ices are essen- models or laboratory experiments have been steadily in- tial reservoirs of carbon, oxygen and nitrogen in molecular creasing, and now appear at a rate ∼ 3 times higher than clouds and protostellar envelopes, but also in protoplan- that of observational papers. This may indicate that the etary disks. They played a key role in forming our solar field is lacking in astronomical data and facilities that can system and determining its composition, and likely play produce them efficiently, while the laboratory astrochem- a similar role for exoplanets. However, it is very hard istry/physics community is eager to contribute. With this to observe and characterize ice in protoplanetary disks, essay, I present some of the reasons why ices are important although we know it is there (Pontoppidan et al. 2005; and exciting, and why we can expect the field to grow in Honda et al. 2009). Most recently, McClure et al. (2015) the future. used Herschel to detect ice in emission in a small number of protoplanetary disks using the far-infrared 60 µm band of crystalline water ice. On the other hand, it is far easier The Galactic ice reservoir to observe ices in dense molecular clouds and protostellar envelopes. Consequently, most of our empirical under- A large reservoir of water in the Milky Way galaxy ex- standing of ices, their distribution and physical chemistry ists in the form of mantles covering sub-micron-sized dust comes from studies of interstellar ice in star-forming re- grains in dense molecular clouds. Water ice appears in gions. dense clouds once the extinction through the cloud (two surfaces) passes above a certain observational threshold of Our observational knowledge of interstellar ices is domi- 3-5mag (Chiar et al. 1995; Boogert et al. 2013). Since nated by spectroscopic surveys with the VLT, Keck, Spitzer,

12 NH 3

H O CH 2 4

- H O OCN 2 CO HCOOH? 2

CH OH 3 CO CH OH 3 NH +? HH46 IRS CH OH 4 3 NH :H O 3 2

Figure 1: The ice bands toward the prototypical solar-mass young stellar object HH46 IRS. The infrared source toward which the ice spectrum is taken, and which drives a large outﬂow, is hidden behind a dense protostellar envelope to the far left of the optical image. The spectra are from VLT-ISAAC and Spitzer (Pontoppidan et al. 2003; the c2d survey, Evans et al. 2003; the Cornell Atlas of Spitzer IRS sources, Lebouteiller et al. 2011). The background image is from the Hubble Space Telescope; NASA, ESA and Hartigan et al. 2011. about 75% of the mass of molecular clouds can be found in- voirs, while interstellar ices on small dust grains only per- side this threshold (Cambresy et al. 2002), and the abun- sist as long as their parent molecular cloud, or a few Myr, dance of water ice relative to elemental hydrogen is rather unless they are accreted onto a protoplanetary disk and well established as ∼ 2 − 10 × 10−5 (Pontoppidan et al. sequestered in planetesimals. 2004; Whittet 2010), we can estimate the total mass of water in molecular cloud ices in the galaxy. If the Milky 9 Way molecular gas mass is 10 M⊙, the Milky Way water From simplicity to complexity 4 ice mass is ∼ 4 × 10 M⊙. A comparatively small amount of water may be found in cool stellar atmospheres. In It is now generally accepted that the molecules comprising interstellar ices are formed by surface reactions. As was al- comparison, the Oort cloud has been estimated to contain ready predicted by van de Hulst (1946), the most common a few tenths of an Earth mass of water ice (Kaib & Quinn 2009; Weissman 1983), with the Kuiper belt contributing surface reaction is hydrogen addition, leading to the formation of saturated species from atomic precursors, such a somewhat smaller fraction of ice mass (Luu & Jewitt 2002). If we disregard the ice that was incorporated into as water, CH4, NH3 (from oxygen, carbon and nitrogen, giant planet cores, which may no longer be in the form respectively). of water, the various icy moons in the solar system con- Simple molecules act as spectroscopic probes of molecular tain another smaller fraction of an Earth mass. If most surfaces in laboratories, and infrared transmission spec- of the 2 × 1011 stars of the Milky Way host similar ice troscopy serves the same role for astrophysical ices. In- reservoirs, this translates to a total Galactic reservoir of deed, extensive laboratory experiments have made funda- 6 ∼ 2 × 10 M⊙ of planetary water ice, almost all of it in mental contributions to our understanding of interstellar comets. Few studies exist investigating the ice content of ices. Initially, the laboratory was used to simulate astro- external galaxies, but it may be a reasonable assumption physical conditions, in particular cryogenic temperatures, that the same statement holds true for the local universe. extremely low pressures and radiation environments, to Of course, we do not know whether exoplanetary systems create transmission spectra of ices for direct comparison all contain Oort clouds of similar mass as that of the Sun, to astronomical observations (Hudgins et al. 1993; Ehren- but it is interesting that the dominant reservoir of water freund et al. 1999). However, as it was realized that some in the Galaxy may be sequestered in comets and other icy astrophysical parameters can never be replicated in the planetesimals, rather than in molecular clouds. Part of laboratory, such as astrophysical time scales of a million the reason for this is that comets are long-lived ice reser- years, the emphasis on the experimental side has shifted

13 Observational publications on interstellar ices Modeling and laboratory publications on interstellar ices

Figure 2: The rate of publications discussing observations of interstellar ices (left) and modeling or laboratory studies (right). The yellow and blue columns show refereed and unrefereed publications, respectively. The figures were created using ADS Labs. somewhat to improve our fundamental understanding of stroyed by protostellar feedback processes, such as shocks the physical chemistry governing ice formation and the in- or thermal heating. In contrast to pure gas-phase chem- teraction of icy mantles with light and radiation. This ap- istry, which is locally well mixed, and often in chemi- proach yields kinetic parameters, reaction rates and the re- cal equilibrium, ice mantles are generally not well-mixed lation between spectroscopic band profiles and the detailed and their chemistry probably never reaches an equilibrium microstructure of the ice (Fraser et al. 2001; Collings state in the few million years they persist in the form of et al. 2004; Oberg¨ et al. 2009b). With the appropri- sub-micron-sized grains in a molecular cloud. As a conse- ate understanding of spectral signatures of ice in hand, quence a typical dust grain will contain a layered record it is remarkable, that, using a telescope equipped with of its local thermal, chemical and radiative environment, an infrared spectrometer, we can in principle determine as well as the time it spent at each stage. As already the detailed molecular configuration of dust grains: which mentioned, we now know that water and CO2 ices form molecular species is in direct intermolecular contact with early on as soon as the cloud is shielded from the inter- others, whether the ices are arranged in smooth spheres or stellar radiation field by ∼ 2 mag (Whittet et al. 2007). in more complex structures, etc. All of this can be accom- This environment corresponds to relatively low densities. plished, not only in the convenient setting of a laboratory, CO formed by classical ion-molecule reactions in the gas- but at distances of 100s of pc, or even in other galaxies phase will only freeze-out onto dust grains at higher den- (Spoon et al. 2003; Yamagishi et al. 2011). While the im- sities and corresponding extinctions. However, because portance of astrophysical ices is often under-appreciated the freeze-out time scale for a gas-phase species scales in- in these times of fashionable exoplanets and dark energy, versely with density, provided the dust grain surfaces are they actually play a fundamental role in many different as- sufficiently cold, it takes longer than the life time of the pects of star and planet formation, as well as, of course, in cloud for CO to freeze out at densities of 104. However, the pathway that carbon, oxygen, nitrogen and hydrogen as densities increase to 106, CO is able to rapidly freeze once took to become part of our own Earth’s atmosphere. out (“catastrophically”; Pontoppidan 2006; Oberg¨ et al. An important realization of the last decade is that in- 2013). This leads to the formation of a layered ice with a, terstellar ice mantles are highly structured and heteroge- likely, quite homogenized mix of water and CO2, covered nous at the individual dust grain level. Ice mantles grow by a thick layer of nearly pure CO. Initially, at the low throughout the evolution of a dense clouds and in proto- temperatures typical for dense molecular clouds and cores ∼ stellar envelopes beyond a few hundred AU. Conversely, (T 10K), these two reservoirs (often referred to as polar desorption processes are comparatively slow, at least until and apolar, with the former being the water-rich mantle) the icy dust grains enter a protoplanetary disk, or are de- are separate and probably do not interact strongly chemi-

14 cally, even though they inhabit the same sub-micron-sized Boogert et al. 2011). dust grains! Why is methanol important? As it turns out, methanol is a key ingredient for forming large amounts of complex organic molecules, including pre-biotic species. The 0. chemical pathways are likely complex, and may derive ei- 0. 0. ther from ice chemistry coupled with ultraviolet irradia- 1. 1. tion (Oberg¨ et al. 2009a) or via gas-phase reactions cat- 1. 3. 2. 2. alyzed by evaporated methanol ice in the vicinity of hot young stars, as observed in hot cores (Nomura & Millar 2004). These complex organic compounds can be quite

2. AV > 10 3. Protostar stable and are likely to survive accretion onto protoplan- 1. A > 2 ‘Late’ V CO H2 etary disks and to take part in the formation of plan- 0. AV < 2 ‘Early’ H CO H2 H2 CO H2 H2 CO etesimals and planets, potentially supporting the develop- N2 H O N H 2 H CO CH 3OH H2 ment of life. ALMA has recently discovered such complex H HO H H H 2 CO H CO CO 2 C+ 2 C O CO CO 2 CO H2 organic molecules in protoplanetary disks (Oberg¨ et al. H O H H O H2O CO OH H OH CH 4 2 CH 4 CO 2 CO 2 NH 3 CO CO NH 3 CO CO 2 H HO CO 2 CH 4 H2O 2 H2O 2015). OH 2 H2O NH 3 H2O Silicate grain core Silicate grain core Silicate grain core Silicate grain core CO-dominated ice H2 O-dominated ice Interstellar ices and star formation with JWST Figure 3: The early evolutionary sequence of interstellar ices as it is currently understood. Starting with bare dust What is the future for observations of ices in planet- and grain surfaces, a thick layer of primarily water and CO2, star-formation? In the past decade, we have answered with traces of ammonia and methane is slowly developed, many questions related to ices, and revealed some of the likely at time scales of 105−6 yr. As the cloud density in- roles it plays in the chemical evolution of circumstellar creases CO freezes out on much shorter time scales, 104 yr material, with fundamental consequences for the initial or less, leading to the formation of a nearly pure CO layer. conditions of planetary composition. But we are far from Prior to or during the formation of protostellar cores, some done. Rather, as usually happens with more data, we now of the CO is converted to methanol. From Oberg¨ et al. have more questions, as well as a clearer idea of what the 2011. questions are. One fundamental problem that we must overcome is that remote sensing of ices has its limitations. The upper pure CO layer may play a quite fundamen- It is incredible that we have determined the structures and tal role in the Universe as part of a chain of events that environments of water, CO2 and CO ices, and to some ultimately lead to the development of habitable worlds degree of methanol. However, there are many more ice (planets and moons). The CO ice is exposed to interac- species of equal or greater importance that we have so far tions with surrounding cloud gas. In particular, this leads been unable to understand. Further, there are still many to the formation of formaldehyde (H2CO) and methanol strong infrared absorption bands that remain unidentified. (CH3OH) by hydrogen addition (Watanabe & Kouchi 2002; Most ice bands are broad, so we have generally spectrally Fuchs et al. 2009; Cuppen et al. 2009). Indeed, if water, resolved them. ammonia and methane are the saturated surface ice ver- sions of gas-phase elemental oxygen, nitrogen and carbon, The next event that will shape our understanding of in- methanol is the saturated ice version of CO. It appar- terstellar ices will be the launch of the James Webb Space ently takes some time to build up appreciable abundances Telescope (JWST). With a telescope diameter 7.5 times of methanol in the CO ice layer, because less evolved that of Spitzer, and medium resolution spectroscopy ex- (younger) quiescent areas of dark clouds tend to not have tending from 1 through 28 µm, JWST seems like the ideal detectable methanol ice (< 1−5% relative to water; Boogert machine for observations of interstellar ices, although it et al. 2013). Nevertheless, methanol continues to build up was never designed with ices in mind. While all of the over time, and perhaps other factors, such as slightly en- JWST instruments are capabable of obtaining various types hanced dust temperatures or increased atomic hydrogen of ice spectroscopy, two in particular stand out. NIRSpec influx, help catalyze the process. Eventually, very high is the near-infrared spectroscopy workhorse. It features methanol abundances of as much as 30% relative to wa- the first multi-object spectrograph capable of observing in ter ice are observed in some of the densest cloud regions the, for ices, critical 3-5 µm region. Using a novel micro- (the Serpens star-forming region is known to have areas shutter array (MSA; Moseley et al. 2004), NIRSpec is with particularly high methanol ice abundances) and in able to obtain 3-5 µm spectra of more than 100 targets si- some protoplanetary envelopes (Pontoppidan et al. 2004; multaneously within a 3 × 3 arcminute field of view at an

15 vations of interstellar ices is the mid-infrared instrument, MIRI. MIRI does not have the multiplexing of NIRSpec, but covers the critical 5-28 µm wavelength region at unprecedented sensitivity and spectral resolution2. MIRI will improve upon the Spitzer spectral resolution by a fac-

JWST NIRSpec multi-object spectrograph field of view tor 4 beyond 10 µm and a factor 30 between 5 and 10 µm. The sensitivity is improved by up to two orders of magnitude at wavelength ranges covering critical ice species, including methane and the highly diagnostic 15.2 µm bend- ing mode of CO2. It also includes the 5-8 µm region, which is filled with ice bands, many of which remain unidentified (Boogert et al. 2008). As with NIRSpec, MIRI opens up a great expanse of discovery space for ices, allowing observations in a much wider range of astrophysical environments than before, from the Galactic center to the Magellanic Clouds. References: Boogert et al. 2008, ApJ, 678, 985 Boogert et al. 2011, ApJ, 729, 92 Figure 4: 3.6-8.0 µm color composite of the isolated dark Boogert et al. 2013, ApJ, 777, 73 core BHR76 as observed by the Spitzer Cores to Disks Boogert, Gerakines & Whittet 2015, ARA&A, 53, in press Legacy program (Evans et al. 2003). The field of view Cambresy et al. 2002, AJ, 123, 2559 of the NIRSpec multi-object spectrograph on the James Chiar et al. 1995, ApJ, 455, 234 Webb Space Telescope is superimposed on the image. The Collings et al. 2004, MNRAS, 354, 1133 densest part of the core is visible in absorption toward Cuppen et al. 2009, 508, 275 diffuse Galactic background emission. The faintest back- Ehrenfreund et al. 1999, A&A, 350, 240 ground stars visible in this image are around 15 µJy at Evans et al. 2003, PASP, 115, 965 4.5 µm; JWST-NIRSpec will be able to obtain ice spec- Fraser et al. 2001, MNRAS, 327, 1165 troscopy toward every single star seen in the image, as Fuchs et al. 2009, A&A, 505, 629 well as many too faint to be detected by Spitzer. Hartigan et al. 2011, 736, 29 Honda et al. 2009, ApJ, 690, 110 Hudgins et al. 1993, ApJS, 86, 714 average resolving power of R ∼ 2700. Reaching a spectro- Kaib & Quinn 2009, Sci, 325, 1234 scopic 10σ sensitivity of around 8 µJy in 1 hour at 4.5µm, Lebouteiller et al. 2011, ApJS, 196, 8 1 NIRSpec represents an astounding 5000-fold increase in Luu & Jewitt 2002, ARA&A, 40, 63 raw sensitivity compared to ISAAC on the Very Large McClure et al. 2015, ApJ, 799, 162 telescope (the previous source of ice spectroscopy at com- Moseley et al. 2004, SPIE, 5487, 645 parable resolving power). Nomura & Millar 2004, A&A, 414, 409 ¨ What this means for ice observations is that JWST will Oberg et al. 2009a, A&A, 504, 891 ¨ be able to efficiently and with very high spatial resolution Oberg et al. 2009b, ApJ, 693, 1209 ¨ map the distribution of major ice species in dense cores Oberg et al. 2011, ApJ, 740, 109 ¨ and even protostellar envelopes by obtaining absorption Oberg et al. 2015, Nature, 520, 198 spectroscopy toward a dense grid of background stars. The Pontoppidan et al. 2004, A&A, 426, 925 match of the NIRSpec multi-object field of view to typical Spoon et al. 2003, A&A, 402, 499 dense cores is illustrated in Figure 4. JWST-NIRSpec will van de Hulst 1946, Recherches Astronomiques de l’Observatoire d’Utrecht, 11, 2 see the formation of water, CO2 and methanol directly, as a function of density and temperature in molecular cloud Watanabe & Kouchi 2002, ApJ, 571, 173 material. It will be able to image the effects of energetic Weissman 1983, A&A, 118, 90 processing on cloud boundaries and by protostellar shocks, Whittet et al. 2007, ApJ, 655, 332 as they occur. Whittet 2010, ApJ, 710, 1009 Yamagishi et al. 2011, ApJ, 731, 20 The other JWST instrument that will revolutionize obser- 1See http://www.stsci.edu/jwst/instruments/nirspec for more details. 2http://www.stsci.edu/jwst/instruments/miri

16 Abstracts of recently accepted papers

Planet formation around binary stars: Tatooine made easy B. C. Bromley1 and S. J. Kenyon2 1 Department of Physics & Astronomy, University of Utah, 115 S 1400 E, Salt Lake City, UT, 84112, USA 2 Smithsonian Astrophysical Observatory, 60 Garden St, Cambridge, MA 02138, USA E-mail contact: bromley at physics.utah.edu We examine characteristics of circumbinary orbits in the context of current planet formation scenarios. Analytical perturbation theory predicts the existence of nested circumbinary orbits that are generalizations of circular paths around a single star. These orbits have forced eccentric motion aligned with the binary as well as higher frequency oscillations, yet they do not cross, even in the presence of massive disks and perturbations from large planets. For this reason, dissipative gas and planetesimals can settle onto these ”most circular” orbits, facilitating the growth of protoplanets. Outside a region close to the binary where orbits are generally unstable, circumbinary planets form in much the same way as their cousins around a single star. Here, we review the theory and conﬁrm its predictions with a suite of representative simulations. We then consider the circumbinary planets discovered with NASA’s Kepler satellite. These Neptune- and Jupiter-size planets, or their planetesimal precursors, may have migrated inward to reach their observed orbits, since their current positions are outside of unstable zones caused by overlapping resonances. In situ formation without migration seems less likely, only because the surface density of the protoplanetary disks must be implausibly high. Otherwise, the circumbinary environment is friendly to planet formation, and we expect that many Earth-like ”Tatooines” will join the growing census of circumbinary planets. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1503.03876

The inner environment of Z CMa: High-Contrast Imaging Polarimetry with NaCo H. Canovas1,6, S. Perez2,6, C. Dougados3, J. de Boer4,7, F. M´enard3, S. Casassus2,6, M.R. Schreiber1,6, L.A. Cieza5,6, C. Caceres1,6, J.H. Girard7 1 Departamento de F´ısica y Astronom´ıa, Universidad de Valpara´ıso, Valpara´ıso, Chile 2 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 3 UMI-FCA, CNRS/INSU, France (UMI 3386), and Dept. de Astronom´ıa, Universidad de Chile, Santiago, Chile 4 Sterrewacht Leiden, Universiteit Leiden, P.O. Box 9513, 2300 RA Leiden, The Netherlands 5 Facultad de Ingenier´ıa, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile 6 Millennium Nucleus “Protoplanetary Disks in ALMA Early Science” 7 European Southern Observatory, Casilla 19001, Santiago, Chile E-mail contact: hector.canovas at dfa.uv.cl Context. ZCMa is a binary composed of an embedded Herbig Be and an FU Ori class star separated by ∼100 au. Observational evidence indicate a complex environment in which each star has a circumstellar disk and drives a jet, and the whole system is embedded in a large dusty envelope. Aims. We aim to probe the circumbinary environment of Z CMa in the inner 400 au in scattered light. Methods. We use high contrast imaging polarimetry with VLT/NaCo at H and Ks bands. Results. The central binary is resolved in both bands. The polarized images show three bright and complex structures: a common dust envelope, a sharp extended feature previously reported in direct light, and an intriguing bright clump located 0′′. 3 south of the binary, which appears spatially connected to the sharp extended feature. Conclusions. We detect orbital motion when compared to previous observations, and report a new outburst driven by the Herbig star. Our observations reveal the complex inner environment of Z CMa with unprecedented detail and contrast.

17 Accepted by A&A Letter http://arxiv.org/pdf/1504.05197

The infrared emission of young Hii regions: A Herschel/Hi-GAL study R. Cesaroni1, M. Pestalozzi2, M. T. Beltran1, M. G. Hoare3, S. Molinari2, L. Olmi1,4, M. D. Smith5, G. S. Stringfellow6, L. Testi7,1 and M. A. Thompson8 1 INAF, Osservatorio Astrofisico di Arcetri, Italy 2 INAF, Istituto di Astrofisica e Planetologia Spaziale, Italy 3 School of Physics and Astrophysics, University of Leeds, UK 4 University of Puerto Rico, Rio Piedras Campus, Physics Dept., Puerto Rico 5 Centre for Astrophysics and Planetary Science, University of Kent, UK 6 Center for Astrophysics and Space Astronomy, University of Colorado, USA 7 European Southern Observatory, Garching, Germany 8 Centre for Astrophysics Research, University of Hertfordshire, UK E-mail contact: cesa at arcetri.astro.it Investigating the relationship between radio and infrared emission of Hii regions may help shed light on the nature of the ionizing stars and the formation mechanism of early-type stars in general. We have taken advantage of recent unbiased surveys of the Galactic plane such as Herschel/Hi-GAL and VLA/CORNISH to study a bona-fide sample of young Hii regions, located in the Galactic longitude range 10◦–65◦, by comparing the mid- and far-IR continuum emission to the radio free-free emission at 5 GHz. We have identified the Hi-GAL counterparts of 230 CORNISH Hii regions and reconstructed the spectral energy distributions of 204 of these by complementing the Hi-GAL fluxes with ancillary data at longer and shorter wavelengths. Using literature data, we obtained a kinematical distance estimate for 200 Hii regions with Hi-GAL counterparts and determined their luminosities by integrating the emission of the corresponding spectral energy distributions. We have also estimated the mass of the associated molecular clumps from the (sub)millimeter flux densities. Our main finding is that for ∼1/3 of the Hii regions the Lyman continuum luminosity appears to be greater than the value expected for a zero-age main-sequence star with the same bolometric luminosity. This result indicates that a considerable fraction of young, embedded early-type stars present a “Lyman excess” possibly due to UV photons emitted from shocked material infalling onto the star itself and/or a circumstellar disk. Finally, by comparing the bolometric and Lyman continuum luminosities with the mass of the associated clump, we derive a star formation efficiency of 5%. The results obtained suggest that accretion may be still present during the early stages of the evolution of Hii regions, with important effects on the production of ionizing photons and thus on the circumstellar environment. More detailed numerical models describing the accretion process onto massive stars are required to shed light on the origin of the observed Lyman excess. Accepted by Astronomy and Astrophysics http://www.arcetri.astro.it/science/starform/preprints/cesa_25.pdf

Early evolution of embedded clusters J.E. Dale1,2, B. Ercolano1,2, I.A. Bonnell3 1 Excellence Cluster ‘Universe’, Boltzmannstr. 2, 85748 Garching, Germany 2 Universitäts–Sternwarte München, Scheinerstr. 1, 81679 München, Germany 3 Department of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS E-mail contact: dale at usm.lmu.de We examine the combined effects of winds and photoionizing radiation from O–type stars on embedded stellar clusters formed in model turbulent molecular clouds covering a range of masses and radii. We find that feedback is able to increase the quantities of dense gas present, but decreases the rate and efficiency of the conversion of gas to stars relative to control simulations in which feedback is absent. Star formation in these calculations often proceeds at a rate substantially slower than the freefall rate in the dense gas. This decoupling is due to the weakening of, and expulsion

18 of gas from, the deepest parts of the clouds’ potential wells where most of the star formation occurs in the control simulations. This results in large fractions of the stellar populations in the feedback simulation becoming dissociated from dense gas. However, where star formation does occur in both control and feedback simulations, it does so in dense gas, so the correlation between star formation activity and dense gas is preserved. The overall dynamical effects of feedback on the clusters are minimal, with only small fraction of stars becoming unbound, despite large quantities of gas being expelled from some clouds. This owes to the settling of the stars into virialised and stellar–dominated configurations before the onset of feedback. By contrast, the effects of feedback on the observable properties of the clusters – their U–, B– and V–band magnitudes – are strong and sudden. The timescales on which the clusters become visible and unobscured are short compared with the timescales which the clouds are actually destroyed. Accepted by MNRAS http://arxiv.org/pdf/1504.05896

Dust trapping by spiral arms in gravitationally unstable protostellar discs Giovanni Dipierro1, Paola Pinilla2, Giuseppe Lodato1, and Leonardo Testi3,4,5 1 Dipartimento di Fisica, Universit degli Studi di Milano, Via Celoria 16, 20133 Milano, Italy 2 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands 3 European Southern Observatory, Karl Schwarzschild str. 2, D-85748 Garching bei Mnchen, Germany 4 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy 5 Excellence Cluster Universe, Boltzmann str. 2, D-85748 Garching bei München, Germany E-mail contact: giovanni.dipierro at unimi.it In this paper we discuss the influence of gravitational instabilities in massive protostellar discs on the dynamics of dust grains. Starting from a Smoothed Particle Hydrodynamics (SPH) simulation, we have computed the evolution of the dust in a quasi-static gas density structure typical of self-gravitating disc. For different grain size distributions we have investigated the capability of spiral arms to trap particles. We have run 3D radiative transfer simulations in order to construct maps of the expected emission at (sub-)millimetre and near-infrared wavelengths. Finally, we have simulated realistic observations of our disc models at (sub-)millimetre and near-infrared wavelengths as they may appear with the Atacama Large Millimetre/sub-millimetre Array (ALMA) and the High-Contrast Coronographic Imager for Adaptive Optics (HiCIAO) in order to investigate whether there are observational signatures of the spiral structure. We find that the pressure inhomogeites induced by gravitational instabilities produce a non-negligible dynamical effect on centimetre sized particles leading to significant overdensities in spiral arms. We also find that the spiral structure is readily detectable by ALMA over a wide range of (sub-)millimetre wavelengths and by HiCIAO in near-infrared scattered light for non-face-on discs located in the Ophiucus star-forming region. In addition, we find clear spatial spectral index variations across the disc, revealing that the dust trapping produces a migration of large grains that can be potentially investigated through multi-wavelenghts observations in the (sub-)millimetric. Therefore, the spiral arms observed to date in protoplanetary disc might be interpreted as density waves induced by the development of gravitational instabilities. Accepted by MNRAS http://arxiv.org/pdf/1504.08099

The number fraction of discs around brown dwarfs in Orion OB1a and the 25 Orionis group Juan JoséDownes1,2, Carlos Román-Zúñiga1, Javier Ballesteros-Paredes3, Cecilia Mateu1,2, César Briceño4, Jesús Hernández2, Monika G. Petr-Gotzens6, Nuria Calvet5, Lee Hartmann5 and Karina Mauco3 1 Instituto de Astronom´ıa, UNAM, Ensenada, C.P. 22860, Baja California, México 2 Centro de Investigaciones de Astronom´ıa, AP 264, Mérida 5101-A, Venezuela 3 Centro de Radioastronom´ıay Astrof´ısica, UNAM. Apartado Postal 72-3 (Xangari), Morelia, Michoacán 58089, México 4 Cerro Tololo Interamerican Observatory, Casilla 603, La Serena, Chile 5 Department of Astronomy, University of Michigan, 825 Dennison Building, 500 Church Street, Ann Arbor, MI 48109,

19 USA 6 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany E-mail contact: jdownes at astrosen.unam.mx We present a study of 15 new brown dwarfs belonging to the ∼ 7 Myr old 25 Orionis group and Orion OB1a sub- association with spectral types between M6 and M9 and estimated masses between ∼ 0.07 M⊙ and ∼ 0.01 M⊙. By comparing them through a Bayesian method with low mass stars (0.8 ∼< M/M⊙ ∼< 0.1) from previous works in the 25 Orionis group, we found statistically significant differences in the number fraction of classical T Tauri stars, weak T Tauri stars, class II, evolved discs and purely photospheric emitters at both sides of the sub-stellar mass limit. +2.4 Particularly we found a fraction of 3.9−1.6 % low mass stars classified as CTTS and class II or evolved discs, against +10.8 a fraction of 33.3−9.8 % in the sub-stellar mass domain. Our results support the suggested scenario in which the dissipation of discs is less efficient for decreasing mass of the central object. Accepted by Monthly Notices of the Royal Astronomical Society http://arxiv.org/pdf/1504.05196

The difficult early stages of embedded star clusters and the importance of the pre-gas expulsion virial ratio J.P. Farias1, R. Smith1,2,3, M. Fellhauer1, S. Goodwin4, G.N. Candlish1, M. Blaña1,5, R. Dominguez1 1 Departamento de Astronomia, Universidad de Concepcion, Casilla 160-C, Concepcion, Chile 2 Yonsei University, Graduate School of Earth System Sciences-Astronomy-Atmospheric Sciences, Yonsei-ro 50, Seoul 120-749, Republic of Korea 3 Laboratoire AIM Paris-Saclay, CEA/IRFU/SAp, CNRS/INSU, UniversitéParis Diderot, 91191 Gif-sur-Yvette Cedex, France 4 Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, UK 5 Max-Planck-Institut für extraterrestrische Physik, Gieenbachstraße 1, D-85748 Garching, Germany E-mail contact: jfarias at asto-udec.cl We examine the effects of gas-expulsion on initially substructured distributions of stars. We perform N-body simulations of the evolution of these distributions in a static background potential to mimic the gas. We remove the static potential instantaneously to model gas-expulsion. We find that the exact dynamical state of the cluster plays a very strong role in affecting a cluster’s survival, especially at early times: they may be entirely destroyed or only weakly affected. We show that knowing both detailed dynamics and relative star-gas distributions can provide a good estimate of the post-gas expulsion state of the cluster, but even knowing these is not an absolute way of determining the survival or otherwise of the cluster. Accepted by MNRAS http://arxiv.org/pdf/1504.02474

Inefficient star formation through turbulence, magnetic fields and feedback Christoph Federrath1 1 Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611, Australia E-mail contact: christoph.federrath at anu.edu.au Star formation is inefficient. Only a few percent of the available gas in molecular clouds forms stars, leading to the observed low star formation rate (SFR). The same holds when averaged over many molecular clouds, such that the SFR of whole galaxies is again surprisingly low. Indeed, considering the low temperatures, molecular clouds should be highly gravitationally unstable and collapse on their global mean freefall timescale. And yet, they are observed to live about 10–100 times longer, i.e., the SFR per freefall time (SFRff ) is only a few percent. Thus, other physical mechanisms must counteract the quick global collapse. Turbulence, magnetic fields and stellar feedback have been proposed as regulating agents, but it is still unclear which of these processes is the most important and what their relative contributions are. Here we run high-resolution simulations including gravity, turbulence, magnetic fields, and

20 jet/outflow feedback. We confirm that clouds collapse on a mean freefall time, if only gravity is considered, producing stars at an unrealistic rate. In contrast, if turbulence, magnetic fields, and feedback are included step-by-step, the SFR is reduced by a factor of 2–3 with each additional physical ingredient. When they all act in concert, we find a constant SFRff = 0.04, currently the closest match to observations, but still about a factor of 2–4 higher than the average. A detailed comparison with other simulations and with observations leads us to conclude that only models with turbulence producing large virial parameters, and including magnetic fields and feedback can produce realistic SFRs. Accepted by MNRAS http://astrobites.org/2015/04/28/why-is-star-formation-so-inefficient/

Resolving the chemical substructure of Orion-KL S. Feng1, H. Beuther1, Th. Henning1, D. Semenov1, Aina Palau2 and E. A. C. Mills3 1 Max-Planck Institute for Astronomy, Heidelberg, Germany 2 Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico 3 National Radio Astronomy Observatory, USA E-mail contact: syfeng at mpe.mpg.de The Kleinmann-Low nebula in Orion (Orion-KL) is the nearest example of a high-mass star-forming environment. For the first time, we complemented 1.3 mm Submillimeter Array (SMA) interferometric line survey with IRAM 30 m single-dish observations of the Orion-KL region. Covering a 4 GHz bandwidth in total, this survey contains over 160 emission lines from 20 species (25 isotopologues), including 10 complex organic molecules (COMs). At a spatial resolution of ∼1200 AU, the continuum substructures are resolved. Extracting the spectra from individual substructures and providing the intensity-integrated distribution map for each species, we studied the small-scale chemical variations in this region. Our main results are: (1) We identify lines from the low-abundance COMs CH3COCH3 and CH3CH2OH, as well as tentatively detect CH3CHO and long carbon-chains C6H and HC7N. (2) We find that while most COMs are segregated by type, peaking either towards the hot core (e.g., nitrogen-bearing species) or the compact ridge (e.g., oxygen-bearing species like HCOOCH3, CH3OCH3, the distributions of others do not follow this segregated structure (e.g., CH3CH2OH, CH3OH, CH3COCH3). (3) We find a second velocity component of HNCO, 34 SO2, and SO lines, which may be associated with a strong shock event in the low-velocity outflow. (4) Temperatures and molecular abundances show large gradients between central condensations and the outflow regions, illustrating a transition between hot molecular core and shock-chemistry dominated regimes. Our observations of spatially resolved chemical variations in Orion-KL provide the nearest reference source for hot molecular core and outflow chemistry, which will be an important example for interpreting the chemistry of more distant HMSFRs. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1504.08012

Tracing the magnetic field morphology of the Lupus I molecular cloud G.A.P. Franco1 and F.O. Alves2 1 Departamento de F´ısica – ICEx – UFMG, Belo Horizonte, Brazil 2 Max-Planck-Institut für extraterrestrische Physik, Garching, Germany E-mail contact: franco at franco.ufmg.br Deep R-band CCD linear polarimetry collected for fields with lines-of-sight toward the Lupus I molecular cloud is used to investigate the properties of the magnetic field within this molecular cloud. The observed sample contains about 7000 stars, almost 2000 of them with polarization signal-to-noise ratio larger than 5. These data cover almost the entire main molecular cloud and also sample two diffuse infrared patches in the neighborhood of Lupus I. The large scale pattern of the plane-of-sky projection of the magnetic field is perpendicular to the main axis of Lupus I, but parallel to the two diffuse infrared patches. A detailed analysis of our polarization data combined with the Herschel/SPIRE 350 µm dust emission map shows that the principal filament of Lupus I is constituted by three main clumps acted by magnetic fields having different large-scale structure properties. These differences may be the reason

21 for the observed distribution of pre- and protostellar objects along the molecular cloud and its apparent evolutive stage. On the other hand, assuming that the magnetic field is composed by a large-scale and a turbulent components, we find that the latter is rather similar in all three clumps. The estimated plane-of-sky component of the large-scale magnetic field ranges from about 70 µG to 200 µG in these clumps. The intensity increases towards the Galactic plane. The mass-to-magnetic flux ratio is much smaller than unity, implying that Lupus I is magnetically supported on large scales. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1504.08222

Prestellar Core Formation, Evolution, and Accretion from Gravitational Fragmentation in Turbulent Converging Flows Munan Gong1 and Eve C. Ostriker1 1 Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA E-mail contact: munan at princeton.edu We investigate prestellar core formation and accretion based on three-dimensional hydrodynamic simulations. Our simulations represent local ∼1 pc regions within giant molecular clouds where a supersonic turbulent flow converges, triggering star formation in the post-shock layer. We include turbulence and self-gravity, applying sink particle techniques, and explore a range of inflow Mach number M = 2–16. Two sets of cores are identified and compared: t1-cores are identified of a time snapshot in each simulation, representing dense structures in a single cloud map; tcoll-cores are identified at their individual time of collapse, representing the initial mass reservoir for accretion. We find that cores and filaments form and evolve at the same time. At the stage of core collapse, there is a well-defined, converged characteristic mass for isothermal fragmentation that is comparable to the critical Bonner-Ebert mass at the post-shock pressure. The core mass functions (CMFs) of tcoll-cores show a deficit of high-mass cores (∼>7 M⊙) compared to the observed stellar initial mass function (IMF). However, the CMFs of t1-cores are similar to the observed CMFs and include many low-mass cores that are gravitationally stable. The difference between t1-cores and tcoll-cores suggests that the full sample from observed CMFs may not evolve into protostars. Individual sink particles accrete at a roughly constant rate throughout the simulations, gaining one tcoll-core mass per free-fall time even after the initial mass reservoir is accreted. High-mass sinks gain proportionally more mass at late times than low-mass sinks. There are outbursts in accretion rates, resulting from clumpy density structures falling into the sinks. Accepted by ApJ http://arxiv.org/pdf/1504.02140

Early Results from VLT SPHERE: Long-Slit Spectroscopy of 2MASS 0122-2439B, a Young Companion Near the Deuterium Burning Limit. Sasha Hinkley1, Brendan P. Bowler2,8, Arthur Vigan3,4, Kimberly M. Aller5, Michael C. Liu5, Dim- itri Mawet6,4, Elisabeth Matthews1, Zahed Wahhaj4, Stefan Kraus1, Isabelle Baraﬀe1,7 and Gilles Chabrier1,7 1 University of Exeter, Astrophysics Group, Physics Building, Stocker Road, Exeter, EX4 4QL, UK. 2 Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, USA 3 Aix Marseille Universit´e, CNRS, LAM (Laboratoire d‘Astrophysique de Marseille) UMR 7326, 13388 Marseille, France. 4 European Southern Observatory, Alonso de Cordova 3107, Vitcura, Santiago, Chile 5 University of Hawaii, Institute of Astronomy, 2860 Woodlawn Drive, Honolulu, HI 96822, USA 6 Department of Astronomy, California Institute of Technology, Mail Code 249-17, 1200 E. California Blvd, Pasadena, CA 91125, USA 7 CRAL, ENS-Lyon (CNRS UMR 5574), Lyon, France 8 Caltech Joint Center for Planetary Astronomy Fellow. E-mail contact: shinkley at gmail.com

22 We present 0.95–1.80 µm spectroscopy of the ∼12–27 MJup companion orbiting the faint (R∼13.6), young (∼120Myr) M-dwarf 2MASS J01225093–2439505(“2M0122–2439B”) at 1.5 arcsecond separation (50 AU). Our coronagraphic long- slit spectroscopy was obtained with the new high contrast imaging platform VLT-SPHERE during Science Verification. The unique long-slit capability of SPHERE enables spectral resolution an order of magnitude higher than other extreme AO exoplanet imaging instruments. With a low mass, cool temperature, and very red colors, 2M0122–2439B occupies a particularly important region of the substellar color-magnitude diagram by bridging the warm directly imaged hot planets with late-M/early-L spectral types (e.g. β Pic b and ROXs 42Bb) and the cooler, dusty objects near the L/T transition (HR 8799bcde and 2MASS 1207b). We fit BT-Settl atmospheric models to our R≈350 spectrum and find Teff =1600±100 K and log(g)=4.5±0.5 dex. Visual analysis of our 2M0122–2439 B spectrum suggests a spectral type L3-L4, and we resolve shallow J-band alkali lines, confirming its low gravity and youth. Specifically, we use the Allers & Liu (2013) spectral indices to quantitatively measure the strength of the FeH, VO, KI, spectral features, as well as the overall H-band shape. Using these indices, along with the visual spectral type analysis, we classify 2M0122–2439 B as an intermediate gravity (“INT-G”) object with spectral type L3.7±1.0. Accepted by ApJ Letters http://arxiv.org/pdf/1504.07240

Interplay of gas and ice during cloud evolution S. Hocuk1,2 and S. Cazaux2 1 Max-Planck-Institut fur extraterrestrische Physik, Giessenbachstrasse 1, 85748, Garching, Germany 2 Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV, Groningen, The Netherlands E-mail contact: seyit at mpe.mpg.de During the evolution of diffuse clouds to molecular clouds, gas-phase molecules freeze out on surfaces of small dust particles to form ices. On dust surfaces, water is the main constituent of the icy mantle in which a complex chemistry is taking place. We aim to study the formation pathways and the composition of the ices throughout the evolution of diffuse clouds. For this purpose, we used time-dependent rate equations to calculate the molecular abundances in the gas phase and on solid surfaces (onto dust grains). We fully considered the gas-dust interplay by including the details of freeze-out, chemical and thermal desorption, and the most important photo-processes on grain surfaces. The difference in binding energies of chemical species on bare and icy surfaces was also incorporated into our equations. Using the numerical code flash, we performed a hydrodynamical simulation of a gravitationally bound diffuse cloud and followed its contraction. We find that while the dust grains are still bare, water formation is enhanced by grain surface chemistry that is subsequently released into the gas phase, enriching the molecular medium. The CO molecules, on the other hand, tend to gradually freeze out on bare grains. This causes CO to be well mixed and strongly present within the first ice layer. Once one monolayer of water ice has formed, the binding energy of the grain surface changes significantly, and an immediate and strong depletion of gas-phase water and CO molecules occurs. While hydrogenation converts solid CO into formaldehyde (H2CO) and methanol (CH3OH), water ice becomes the main constituent of the icy grains. Inside molecular clumps formaldehyde is more abundant than water and methanol in the gas phase, owing its presence in part to chemical desorption. Accepted by Astronomy & Astrophysics http://adsabs.harvard.edu/abs/2015A\%26A...576A..49H

Long-term multicolor photometry of the young stellar objects FHO 26, FHO 27, FHO 28, FHO 29 and V1929 Cygni S.I. Ibryamov1, E.H. Semkov1 and S.P. Peneva1 1 Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences, 72, Tsarigradsko Shose Blvd., 1784 Soﬁa, Bulgaria E-mail contact: sibryamov at astro.bas.bg Results from long-term multicolor optical photometric observations of the pre-main sequence stars FHO 26, FHO 27, FHO 28, FHO 29 and V1929 Cyg collected during the period from June 1997 to December 2014 are presented. The objects are located in the dense molecular cloud L935, named ”Gulf of Mexico”, in the ﬁeld between the North

23 America and Pelican nebulae. All stars from our study exhibit strong photometric variability in all optical passbands. Using our BVRI observations and data published by other authors, we tried to deﬁne the reasons for the observed brightness variations. The presented paper is a part of our long-term photometric study of the young stellar objects in the region of ”Gulf of Mexico”. Accepted by Publications of the Astronomical Society of Australia (PASA) http://arxiv.org/pdf/1504.06774

A debris disk under the inﬂuence of a wide planetary mass companion: The system of HD106906 Lucie J´ılkov´a1 and Simon Portegies Zwart1 1 Leiden Observatory, Niels Bohrweg 2, Leiden, 2333 CA, The Netherlands E-mail contact: jilkova at strw.leidenuniv.nl

The 13 Myr old star HD106906 is orbited by a debris disk of at least 0.067 MMoon with an inner and outer radius of 20 AU and 120 AU, respectively, and by a planet at a distance of 650 AU. We use this curious combination of a close low-mass disk and a wide planet to motivate our simulations of this system. We study the parameter space of the initial conditions to quantify the mass loss from the debris disk and its lifetime under the influence of the planet. We find that when the planet orbits closer to the star than about 50 AU and with low inclination relative to the disk (less than about 10 ◦), more disk material is perturbed outside than inside the region constrained by observations on timescales shorter than 1 Myr. Considering the age of the system, such a short lifetime of the disk is incompatible with the timescale for planet–planet scattering which is one of the scenarios suggested to explain the wide separation of the planet. For some configurations when the planet’s orbit is inclined with respect to the disk, the latter will start to wobble. We argue that this wobbling is caused by a mechanism similar to the Kozai–Lidov oscillations. We also observe various resonant structures (such as rings and spiral arms) induced in the disk by the planet. Accepted by MNRAS http://arxiv.org/pdf/1504.05702

Ice chemistry in starless molecular cores J. Kalv¯ans1 1 Engineering Research Institute “Ventspils International Radio Astronomy Center” of Ventspils University College, Inzenieru 101, Ventspils, Latvia, LV-3601 E-mail contact: juris.kalvans at venta.lv Starless molecular cores are natural laboratories for interstellar molecular chemistry research. The chemistry of ices in such objects was investigated with a three-phase (gas, surface, and mantle) model. We considered the center part of ﬁve starless cores, with their physical conditions derived from observations. The ice chemistry of oxygen, nitrogen, sulfur, and complex organic molecules (COMs) was analyzed. We found that an ice-depth dimension, measured, e.g., in monolayers, is essential for modeling of chemistry in interstellar ices. Particularly, the H2O:CO:CO2:N2:NH3 ice abundance ratio regulates the production and destruction of minor species. It is suggested that photodesorption during core collapse period is responsible for high abundance of interstellar H2O2 and O2H, and other species synthesized on the surface. The calculated abundances of COMs in ice were compared to observed gas-phase values. Smaller activation barriers for CO and H2CO hydrogenation may help explain the production of a number of COMs. The observed abundance of methyl formate HCOOCH3 could be reproduced with a 1kyr, 20K temperature spike. Possible desorption mechanisms, relevant for COMs, are gas turbulence (ice exposure to interstellar photons) or a weak shock within the cloud core (grain collisions). To reproduce the observed COM abundances with the present 0D model, 1–10% of ice mass needs to be sublimated. We estimate that the lifetime for starless cores likely does not exceed 1Myr. Taurus cores are likely to be younger than their counterparts in most other clouds. Accepted by ApJ http://arxiv.org/pdf/1504.06065

24 A Ring of C2H in the Molecular Disk Orbiting TW Hya Joel H. Kastner1, Chunhua Qi2, Uma Gorti3, Pierre Hily-Blant4,5, Karin Oberg2, Thierry Forveille4, Sean Andrews2, David Wilner2 1 Chester F. Carlson Center for Imaging Science, School of Physics & Astronomy, and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester NY 14623 USA 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 3 SETI Institute, 189 Bernardo Ave., Mountain View, CA 94043, USA; NASA Ames Research Center, Moffett Field, CA 94035, USA 4 UniversitéGrenoble Alpes, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), F-38000, Grenoble, France; CNRS, IPAG, F-38000, Grenoble, France 5 Institut Universitaire de France, F-38000, Grenoble, France E-mail contact: jhk at cis.rit.edu ′′ We have used the Submillimeter Array to image, at ∼1. 5 resolution, C2H (3–2) emission from the circumstellar disk orbiting the nearby (D = 54 pc), ∼8 Myr-old, ∼0.8 M⊙ classical T Tauri star TW Hya. The SMA imaging reveals that the C2H emission exhibits a ring-like morphology. Based on a model in which the C2H column density follows a truncated radial power-law distribution, we find that the inner edge of the ring lies at ∼45 AU, and that the ring extends to at least ∼120 AU. Comparison with previous (single-dish) observations of C2H (4–3) emission indicates that the C2H molecules are subthermally excited and, hence, that the emission arises from the relatively warm, tenuous upper atmosphere of the disk. We propose that the C2H emission most likely traces particularly efficient photo-destruction of small grains and/or photodesorption and photodissociation of hydrocarbons derived from grain ice mantles in the surface layers of the outer disk. The presence of a C2H ring in the TW Hya disk hence likely serves as a marker of dust grain processing and radial and vertical grain size segregation within the disk. Accepted by ApJ http://arxiv.org/pdf/1504.05980

Formation of Super-Earth Mass Planets at 125–250 AU from a Solar-type Star Scott J. Kenyon1 and Benjamin C. Bromley2 1 Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 USA 2 Department of Physics, University of Utah, 201 JFB, Salt Lake City, UT 84112 USA E-mail contact: kenyon at cfa.harvard.edu

We investigate pathways for the formation of icy super-Earth mass planets orbiting at 125–250 AU around a 1 M⊙ star. An extensive suite of coagulation calculations demonstrates that swarms of 1 cm to 10 m planetesimals can form super-Earth mass planets on time scales of 1–3 Gyr. Collisional damping of 10−2 − 102 cm particles during oligarchic growth is a highlight of these simulations. In some situations, damping initiates a second runaway growth phase where 1000–3000 km protoplanets grow to super-Earth sizes. Our results establish the initial conditions and physical processes required for in situ formation of super-Earth planets at large distances from the host star. For nearby dusty disks in HD 107146, HD 202628, and HD 207129, ongoing super-Earth formation at 80–150 AU could produce gaps and other structures in the debris. In the solar system, forming a putative planet X at a < 300 AU (a > 1000 AU) requires a modest (very massive) protosolar nebula. Accepted by Astrophysical Journal http://arxiv.org/pdf/1501.05659

Evidence for Decay of Turbulence by MHD Shocks in Molecular Clouds via CO Emission Rebecca L. Larson1, Neal J. Evans II1, Joel D. Green1,2 and Yao-Lun Yang1 1 University of Texas at Austin, Department of Astronomy, Austin, TX 2 Space Telescope Science Institute, Baltimore, MD E-mail contact: saturnswings at gmail.com

25 We utilize observations of sub-millimeter rotational transitions of CO from a Herschel Cycle 2 open time program (“COPS”, PI: J. Green) to identify previously predicted turbulent dissipation by magnetohydrodynamic (MHD) shocks in molecular clouds. We find evidence of the shocks expected for dissipation of MHD turbulence in material not associated with any protostar. Two models fit about equally well: model 1 has a density of 103 cm−3, a shock velocity of3km s−1, and a magnetic field strength of 4 µG; model 2 has a density of 103.5 cm−3, a shock velocity of 2 km s−1, and a magnetic field strength of 8 µG. Timescales for decay of turbulence in this region are comparable to crossing times. Transitions of CO up to J of 8, observed close to active sites of star formation, but not within outflows, can trace turbulent dissipation of shocks stirred by formation processes. Although the transitions are difficult to detect at individual positions, our Herschel-SPIRE survey of protostars provides a grid of spatially-distributed spectra within molecular clouds. We averaged all spatial positions away from known outflows near seven protostars. We find significant agreement with predictions of models of turbulent dissipation in slightly denser (103.5 cm−3) material with a stronger magnetic field (24 µG) than in the general molecular cloud. Accepted by The Astrophysical Journal http://arxiv.org/pdf/1505.00847

Smoothed particle magnetohydrodynamic simulations of protostellar outflows with misaligned magnetic field and rotation axes Benjamin T. Lewis1,2, Matthew R. Bate1,2 and Daniel J. Price2 1 School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK 2 Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, Clayton, Vic 3800, Australia E-mail contact: blewis at astro.ex.ac.uk We have developed a modified form of the equations of smoothed particle magnetohydrodynamics which are stable in the presence of very steep density gradients. Using this formalism, we have performed simulations of the collapse of magnetised molecular cloud cores to form protostars and drive outflows. Our stable formalism allows for smaller sink particles (< 5 AU) than used previously and the investigation of the effect of varying the angle, θ, between the initial field axis and the rotation axis. The nature of the outflows depends strongly on this angle: jet-like outflows are not produced at all when θ > 30◦, and a collimated outflow is not sustained when θ > 10◦. No substantial outflows of any kind are produced when θ > 60◦. This may place constraints on the geometry of the magnetic field in molecular clouds where bipolar outflows are seen. Animations can be found at http://www.astro.ex.ac.uk/people/blewis/research/outflows misaligned fields.html Accepted by MNRAS http://arxiv.org/pdf/1504.08322v1

G-virial: Gravity-based structure analysis of molecular clouds Guang-Xing Li1, Friedrich Wyrowski1, Karl Menten1, Tom Megeath2 and Xun Shi3 1 MPIfR Bonn, Germany 2 University of Toledo, USA 3 MPA Garching, Germany E-mail contact: gxli at mpifr.de Accepted by A&A We present the G-virial method (http://gxli.github.io/G-virial/) which aims to quantify (1) the importance of gravity in molecular clouds in the position-position-velocity (PPV) space, and (2) properties of the gas condensations in molecular clouds. Different from previous approaches that calculate the virial parameter for different regions, our new method takes gravitational interactions between all the voxels in 3D PPV data cubes into account, and generates maps of the importance of gravity. This map can be combined with the original data cube to derive relations such as the mass-radius relation. Our method is important for several reasons. First, it offers the the ability to quantify the centrally condensed structures in the 3D PPV data cubes, and enables us to compare them in an uniform framework. Second, it allows us to understand the importance of gravity at different locations in the data cube, and provides a

26 global picture of gravity in clouds. Third, it offers a robust approach to decomposing the data into different regions which are gravitationally coherent. To demonstrate the application of our method we identified regions from the Perseus and Ophiuchus molecular clouds, and analyzed their properties. We found an increase in the importance of gravity towards the centers of the individual molecular condensations. We also quantified the properties of the regions in terms of mass-radius and mass-velocity relations. Through evaluating the virial parameters based on the G-virial, we found that all our regions are almost gravitationally bound. Cluster-forming regions appear are more centrally condensed. Accepted by A&A http://arxiv.org/pdf/1504.01003

ALMA Resolves the Spiraling Accretion Flow in the Luminous OB Cluster-Forming Region G33.92+0.11 Hauyu Baobab Liu1, Roberto Galván-Madrid2, Izaskun Jiménez-Serra3, Carlos Román-Zúñiga4, Qizhou Zhang5, Zhiyun Li6 and Huei-Ru Chen7 1 Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan 2 Centro de Radioastronomia y Astrofisica, UNAM, A.P. 3-72, Xangari, Morelia 58089, Mexico 3 European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany 4 Instituto de Astronomia, UNAM, Unidad Academica en Ensenada, Ensenada 22860, Mexico 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 6 Department of Astronomy, P.O. Box 400325, Charlottesville, VA 22904, USA 7 Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan E-mail contact: baobabyoo at gmail.com How rapidly collapsing parsec-scale massive molecular clumps feed high-mass stars, and how they fragment to form OB clusters, have been outstanding questions in the field of star-formation. In this work, we report the resolved structures and kinematics of the approximately face-on, rotating massive molecular clump, G33.92+0.11. Our high resolution Atacama Large Millimeter/submillimeter Array (ALMA) images show that the spiral arm-like gas overdensities form in the eccentric gas accretion streams. First, we resolved that the dominant part of the ∼0.6 pc scale massive molecular +2.8· 3 clump (3.0−1.4 10 M⊙) G33.92+0.11A is tangled with several 0.5-1 pc size molecular arms spiraling around it, which may be connected further to exterior gas accretion streams. Within G33.92+0.11A, we resolved the ∼0.1 pc width gas mini-arms connecting with the two central massive (100-300 M⊙) molecular cores. The kinematics of arms and cores elucidate a coherent accretion flow continuing from large to small scales. We demonstrate that the large molecular arms are indeed the cradles of dense cores, which are likely current or future sites of high-mass star formation. Since these deeply embedded massive molecular clumps preferentially form the highest mass stars in the clusters, we argue that dense cores fed by or formed within molecular arms play a key role in making the upper end of the stellar and core mass functions. Accepted by ApJ (804, 37, 2015)

Far-infrared CO and H2O emission in intermediate-mass protostars M. Matuszak1, A. Karska1, L. E. Kristensen2, G. J. Herczeg3, L. Tychoniec1, T.A. van Kempen4 and A. Fuente5 1 Astronomical Observatory, Adam Mickiewicz University, Sloneczna 36, PL-60-268 Poznan, Poland 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 3 Kavli Institut for Astronomy and Astrophysics, Yi He Yuan Lu 5, HaiDian Qu, Peking University, Beijing, 100871, PR China 4 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands 4 Observatorio Astron´omico Nacional (OAN, IGN), Apdo 112, 28803 Alcal´ade Henares, Spain E-mail contact: agata.karska at amu.edu.pl Context: Intermediate-mass young stellar objects (YSOs) provide a link to understanding how feedback from shocks and UV radiation scales from low- to high-mass star forming regions.

27 Aims: Our aim is to analyze excitation of CO and H2O in deeply embedded intermediate-mass YSOs and compare it with similar studies on low-mass and high-mass YSOs. 2 3 Methods: Herschel/PACS spectral maps are analyzed for six YSOs with bolometric luminosities of Lbol ∼ 10 − 10 4 L⊙. The maps cover spatial scales of ∼ 10 AU in several CO and H2O lines located in the ∼ 55 − 210 µm range. Results: Rotational diagrams of CO show two temperature components at Trot ∼ 320 K and Trot ∼ 700 − 800 K, comparable to low- and high-mass protostars probed at similar spatial scales. The diagrams for H2O show a single component at Trot ∼ 130 K, as seen in low-mass protostars, and about 100 K lower than in high-mass protostars. Since the uncertainties in Trot are on the same order as the diﬀerence between the intermediate and high-mass protostars, we cannot conclude whether the change in rotational temperature occurs at a speciﬁc luminosity or whether the change is more gradual from low- to high-mass YSOs. Conclusions: Molecular excitation in intermediate-mass protostars is comparable to the central 103 AU of low-mass protostars and consistent within the uncertainties with the high-mass protostars probed at 3·103 AU scales, suggesting similar shock conditions in all those sources. Accepted by A&A http://arxiv.org/pdf/1504.03347

The Pillars of Creation revisited with MUSE: gas kinematics and high-mass stellar feedback traced by optical spectroscopy A.F. Mc Leod1, J.E. Dale2,3, A. Ginsburg1, B. Ercolano2,3, M. Gritschneder2, S. Ramsay1, and L. Testi1,4 1 European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei Mnchen, Germany 2 Universitäts-Sternwarte München, Scheinerstr. 1, D-81679 Mnchen, Germany 3 Excellence Cluster ‘Universe’, Boltzmannstr. 2, D-85748 Garching bei München, Germany 4 INAF/Osservatorio Astrofisico of Arcetri, Largo E. Fermi, 5, 50125 Firenze, Italy E-mail contact: amcleod at eso.org Integral field unit (IFU) data of the iconic Pillars of Creation in M16 are presented. The ionisation structure of the pillars was studied in great detail over almost the entire visible wavelength range, and maps of the relevant physical parameters, e.g. extinction, electron density, electron temperature, line-of-sight velocity of the ionised and neutral gas are shown. In agreement with previous authors, we find that the pillar tips are being ionised and photo-evaporated by the massive members of the nearby cluster NGC 6611. They display a stratified ionisation structure where the emission lines peak in a descending order according to their ionisation energies. The IFU data allowed us to analyse the kinematics of the photo-evaporative flow in terms of the stratified ionisation structure, and we find that, in agreement with simulations, the photo-evaporative flow is traced by a blueshift in the position-velocity profile. The gas kinematics and ionisation structure have allowed us to produce a sketch of the 3D geometry of the Pillars, positioning the pillars with respect to the ionising cluster stars. We use a novel method to detect a previously unknown bipolar outflow at the tip of the middle pillar and suggest that it has an embedded protostar as its driving source. Furthermore we identify a candidate outflow in the leftmost pillar. With the derived physical parameters and ionic abundances, we −1 estimate a mass loss rate due to the photo-evaporative flow of 70 M⊙ Myr which yields an expected lifetime of approximately 3 Myr. Accepted by MNRAS http://arxiv.org/pdf/1504.03323

Detailed Kinematic Investigation of Herbig-Haro Objects in the Northeast Region of NGC 7129 T.A. Movsessian1, T.Yu. Magakian1, A.V. Moiseev2 and M.G. Gevorgian1 1 Byurakan Astrophysical Observatory, Byurakan, 0213 Armenia 2 Special Astrophysical Observatory, RAS, Nizhnii Arkhyz, 369167 Russia E-mail contact: tigmov at web.am Using the Fabry-Perot scanning interferometer at the SAO RAS 6-m telescope, we studied a number of Herbig-Haro

28 objects in the northeast region of NGC 7129. We detected a helicoidal flow in HH 234, consisting of separate high- speed knots propagating within the cavity in interstellar medium created by the outflow. HH 235 consists of at least five knots, each of which form its own bow shock. The direction of these fronts together with the NW-SE oriented high-velocity core of the flow indicates the location of a possible source. The origin of the objects HH 105 and HH 821 is discussed as well. Possible Herbig-Haro outflow sources in this region are located further north of the cluster center in the vicinity of the active star V350 Cep, except for HH 234 with a known source. It can be considered ascertained that NGC 7129 region consists of several star-forming cores, in which the multiple outflows from stars of different masses are present. Accepted by Astrophysical Bulletin (Vol. 70, No. 2, 2015)

C2H observations toward the Orion Bar Z. Nagy1,2, V. Ossenkopf2, F. F. S. van der Tak3, A. Faure4, Z. Makai2 and E. A. Bergin5 1 Department of Physics and Astronomy, University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606, USA 2 I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany 3 Kapteyn Astronomical Institute, University of Groningen and SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands 4 UniversitéJoseph Fourier/CNRS, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, 38041 Grenoble, France 5 University of Michigan, Ann Arbor, MI 48197, USA E-mail contact: zsofia.nagy.astro at gmail.com

The ethynyl radical (C2H) is one of the first radicals to be detected in the interstellar medium. Its higher rotational transitions have recently become available with the Herschel Space Observatory. We aim to constrain the physical parameters of the C2H emitting gas toward the Orion Bar. + We analyse the C2H line intensities measured toward the Orion Bar CO Peak and Herschel/HIFI maps of C2H, + CH, and HCO , and a NANTEN map of [Ci]. We interpret the observed C2H emission using the combination of Herschel/HIFI and NANTEN data with radiative transfer and PDR models. Five rotational transitions of C2H (from N=6−5 up to N=10−9) have been detected in the HIFI frequency range + toward the CO peak of the Orion Bar. Based on the five detected C2H transitions, a single component rotational 13 −2 diagram analysis gives a rotation temperature of ∼64 K and a beam-averaged C2H column density of 4 × 10 cm . The rotational diagram is also consistent with a two-component fit resulting in rotation temperatures of 43±0.2 K and 123±21 K, and beam-averaged column densities of ∼ 8.3 × 1013 cm−2 and ∼ 2.3 × 1013 cm−2 for the three lower-N and for the three higher-N transitions, respectively. The measured five rotational transitions cannot be explained by any single parameter model. According to a non-LTE model, most of the C2H column density produces the lower−N C2H transitions and traces a warm (Tkin ∼ 100 − 150 5 6 −3 K) and dense (n(H2)∼10 -10 cm ) gas. A small fraction of the C2H column density is required to reproduce the 6 −3 intensity of the highest-N transitions (N=9−8 and N=10−9) originating from a high density (n(H2)∼5×10 cm ) 14 −2 hot (Tkin ∼ 400 K) gas. The total beam-averaged C2H column density in the model is 10 cm . A comparison of + the spatial distribution of C2H to those of CH, HCO , and [Ci] shows the best correlation with CH. Both the non-LTE radiative transfer model and a simple PDR model representing the Orion Bar with a plane-parallel slab of gas and dust suggest, that C2H cannot be described by a single pressure component, unlike the reactive ion CH+, which was previously analysed toward the Orion Bar CO+ peak. The physical parameters traced by the higher rotational transitions (N=6-5,...,10-9) of C2H may be consistent with the edges of dense clumps exposed to UV radiation near the ionization front of the Orion Bar. Accepted by A&A http://arxiv.org/pdf/1405.3903

Demographics of transition discs in Ophiuchus and Taurus Joan R. Najita1,2, Sean M. Andrews2 and James Muzerolle3 1 National Optical Astronomy Observatory, 950 N. Cherry Ave, Tucson, AZ 85719 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138

29 3 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 E-mail contact: najita at noao.edu Transition disc systems are young stars that appear to be on the verge of dispersing their protoplanetary discs. We explore the nature of these systems by comparing the stellar accretion rates and disc masses of transition discs and normal T Tauri stars in Taurus and Ophiuchus. After controlling for the known dependences of stellar accretion rate and disc mass on age, accretion rate on stellar mass, and disc mass on the presence of stellar or substellar companions, we ﬁnd that the normal T Tauri stars show a trend of stellar accretion rate increasing with disc mass. The transition discs tend to have higher average disc masses than normal T Tauri stars as well as lower accretion rates than normal T Tauri stars of the same disc mass. These results are most consistent with the interpretation that the transition discs have formed objects massive enough to alter the accretion ﬂow, i.e. single or multiple giant planets. Several Ophiuchus T Tauri stars that are not known transition disc ???systems also have very low accretion rates for their disc masses. We speculate on the possible nature of these sources. Accepted by MNRAS http://arxiv.org/pdf/1504.05198

A Survey of Extended H2 Emission from Massive YSOs Felipe Navarete1, Augusto Damineli1, Cassio L. Barbosa2 and Robert D. Blum3 1 Instituto de Astronomia, Geofisica e Ciencias Atmosfericas - University of Sao Paulo (IAG-USP) 2 MCTI/Laboratorio Nacional de Astrofisica 3 National Optical Astronomy Observatory (NOAO) E-mail contact: navarete at usp.br We present the results from a survey, designed to investigate the accretion process of massive young stellar objects (MYSOs) through near infrared narrow band imaging using the H2 ν=1-0 S(1) transition filter. A sample of 353 Massive Young Stellar Object (MYSO) candidates was selected from the Red MSX Source survey using photometric criteria at longer wavelengths (infrared and submillimeter) and chosen with positions throughout the Galactic Plane. Our survey was carried out at the SOAR Telescope in Chile and CFHT in Hawaii covering both hemispheres. The data reveal that extended H2 emission is a good tracer of outflow activity, which is a signpost of accretion process on young massive stars. Almost half of the sample exhibit extended H2 emission and 74 sources (21%) have polar morphology, suggesting collimated outflows. The polar-like structures are more likely to appear on radio-quiet sources, indicating these structures occur during the pre-UCHII phase. We also found an important fraction of sources associated with fluorescent H2 diffuse emission that could be due to a more evolved phase. The images also indicate only ∼23% (80) of the sample is associated with extant (young) stellar clusters. These results support the scenario in which massive stars are formed by accretion disks, since the merging of low mass stars would not produce outflow structures. Accepted by MNRAS http://arxiv.org/pdf/1504.06174

The Three-mm Ultimate Mopra Milky Way Survey. II. Cloud and Star Formation Near the Filamentary Ministarburst RCW 106 Hans Nguyêñ1,2, Quang Nguyêñ Lu’o’ng1,3,4, Peter G. Martin1, Peter J. Barnes5,6, Erik Muller4, Vicki Lowe7,8, Nadia Lo9, Maria Cunningham8, Frédérique Motte10, Balthasar Indermühle7, Stefan N. O’Dougherty11, Audra K. Hernandez12 and Gary A. Fuller13 1 Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada 2 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany 3 EACOA Fellow at NAOJ, Japan & KASI, Korea 4 National Astronomical Observatory of Japan, Chile Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 5 Astronomy Department, University of Florida, P.O. Box 112055, Gainesville, FL 32611, USA 6 School of Science and Technology, University of New England, NSW 2351, Australia 7 CSIRO Astronomy and Space Science, P.O. Box 76, Epping, NSW 1710, Australia

30 8 School of Physics, University of New West Wales, NSW 2052 Australia 9 Departamento de Astronom´ıa, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Casilla 36-D, Chile 10 Laboratoire AIM Paris-Saclay, CEA/IRFU - CNRS/INSU - Université Paris Diderot, Service d’Astrophysique, Bât. 709, CEA-Saclay, F-91191, Gif-sur-Yvette Cedex, France 11 College of Optical Sciences, University of Arizona, 1630 E. University Blvd., P.O. Box 210094, Tucson, AZ 85721, USA 12 Astronomy Department, University of Wisconsin, 475 East Charter St., Madison, WI 53706, USA 13 Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, University of Manchester, Manchester, M13 3PL., UK E-mail contact: hnguyen at mpifr-bonn.mpg.de We report here a study of gas, dust and star formation rates (SFRs) in the molecular cloud complexes (MCCs) surrounding the giant H II region RCW 106 using 12CO and 13CO (1-0) data from the Three-mm Ultimate Mopra Milky way Survey (ThrUMMS) and archival data. We separate the emission in the Galactic Plane around l = 330◦- ◦ ◦ ◦ −1 335 and b = −1 -1 into two main MCCs: the RCW 106 (VLSR = −48kms ) complex and the MCC331-90(VLSR = −1 6 −90kms ) complex. While RCW 106 (M∼ 5.9 × 10 M⊙) is located in the Scutum-Centaurus arm at a distance 6 of 3.6kpc, MCC331-90 (M∼ 2.8 × 10 M⊙) is in the Norma arm at a distance of 5 kpc. Their molecular gas mass −2 surface densities are ∼ 220 and ∼ 130M⊙ pc , respectively. For RCW 106 complex, using the 21 cm continuum fluxes and dense clump counting, we obtain an immediate past (∼-0.2 Myr) and an immediate future (∼+0.2 Myr) SFRs of +0.09 −1 ± −1 +3.4 −1 −2 0.25−0.023 M⊙, yr and 0.12 0.1 M⊙ yr . This results in an immediate past SFR density of 9.5−0.9 M⊙ yr kpc +3.8 −1 −2 and an immediate future SFR density of 4.8−3.8 M⊙ yr kpc . As both SFRs in this cloud are higher than the ministarburst threshold, they must be undergoing a ministarburst event although burst peak has already passed. We conclude that this is one of the most active star forming complexes in the southern sky, ideal for further investigations of massive star formation and potentially shedding light on the physics of high-redshift starbursts. Accepted by ApJ https://publications.mpifr-bonn.mpg.de/manuscripts/uploads/hnguyen1428574191.pdf http://arxiv.org/pdf/1504.02246

Long-Slit Spectroscopy of Parsec-Scale Jets from DG Tauri Heeyoung Oh1,2, Tae-Soo Pyo3,4, In-Soo Yuk2 and Byeong-Gon Park1,2 1 Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 305-350, Korea 2 Korea Astronomy and Space Science Institute,776 Daedeokdae-ro, Yuseong-gu, Daejeon 305-348, Korea 3 Subaru Telescope, National Astronomical Observatory of Japan, 650 North A’ohoku Place, Hilo, HI 96720 4 School of Mathematical and Physical Science, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa 240-0193, Japan E-mail contact: hyoh at kasi.re.kr We present observational results from optical long-slit spectroscopy of parsec-scale jets of DG Tau. From HH 158 and HH 702, the optical emission lines of Hα, [O I] λλ6300, 6363, [N II] λλ6548, 6584, and [S II] λλ6716, 6731 are obtained. The kinematics and physical properties (i.e., electron density, electron temperature, ionization fraction, and mass-loss rate) are investigated along the blueshifted jet up to 650′′ distance from the source. For HH 158, the radial velocity ranges from −50 to −250 km s−1. The proper motion of the knots is 0′′. 196 − 0′′. 272 yr−1. The electron density is ∼104 cm−3 close to the star, and decreases to ∼102 cm−3 at 14 arcsec away from the star. Ionization fraction indicates that the gas is almost neutral in the vicinity of the source. It increases up to over 0.4 along the distance. HH 702 is located at 650 arcsec from the source. It shows ∼ −80 km s−1 in the radial velocity. Its line ratios are similar to −7 −1 those at knot C of HH 158. The mass-loss rate is estimated to be about ∼ 10 M⊙ yr , which is similar to values obtained from previous studies. Accepted by Journal of The Korean Astronomical Society http://arxiv.org/pdf/1505.00942.pdf

31 Circumstellar Disks revealed by H/K Flux Variation Gradients F. Pozo Nunez1, M. Haas1, R. Chini1,2, M. Ramolla1, C. Westhues1 and K.-W. Hodapp3 1 Astronomisches Institut, Ruhr-Universitat Bochum, Universitatsstrasse 150, 44801 Bochum, Germany 2 Instituto de Astronomia, Universidad Catolica del Norte, Avenida Angamos 0610, Casilla 1280 Antofagasta, Chile 3 Institute for Astronomy, University of Hawaii, 640 N. Aohoku Place, Hilo HI 96720, USA E-mail contact: fpozo at astro.rub.de The variability of young stellar objects (YSO) changes their brightness and color preventing a proper classification in traditional color-color and color magnitude diagrams. We have explored the feasibility of the flux variation gradient (FVG) method for YSOs, using H and K band monitoring data of the star forming region RCW 38 obtained at the University Observatory Bochum in Chile. Simultaneous multi-epoch flux measurements follow a linear relation FH = α+β·FK for almost all YSOs with large variability amplitude. The slope β gives the mean HK color temperature Tvar of the varying component. Because Tvar is hotter than the dust sublimation temperature, we have tentatively assigned it to stellar variations. If the gradient does not meet the origin of the flux-flux diagram, an additional non- or less-varying component may be required. If the variability amplitude is larger at the shorter wavelength, e.g. α< 0, this component is cooler than the star (e.g. a circumstellar disk); vice versa, if α> 0, the component is hotter like a scattering halo or even a companion star. We here present examples of two YSOs, where the HK FVG implies the presence of a circumstellar disk; this finding is consistent with additional data at J and L. One YSO shows a clear K-band excess in the JHK color-color diagram, while the significance of a K-excess in the other YSO depends on the measurement epoch. Disentangling the contributions of star and disk it turns out that the two YSOs have huge variability amplitudes (∼ 3 − 5 mag). The HK FVG analysis is a powerful complementary tool to analyze the varying components of YSOs and worth further exploration of monitoring data at other wavelengths. Accepted by Astronomy and Astrophysics http://arxiv.org/pdf/1504.07562

High-contrast imaging constraints on gas giant planet formation - The Herbig Ae/Be star opportunity Sascha P. Quanz1 1 ETH Zurich, Institute for Astronomy, Wolfgang-Pauli-Strasse, 8053 Zurich, Switzerland E-mail contact: sascha.quanz at astro.phys.ethz.ch Planet formation studies are often focused on solar-type stars, implicitly considering our Sun as reference point. This approach overlooks, however, that Herbig Ae/Be stars are in some sense much better targets to study planet formation processes empirically, with their disks generally being larger, brighter and simply easier to observe across a large wavelength range. In addition, massive gas giant planets have been found on wide orbits around early type stars, triggering the question if these objects did indeed form there and, if so, by what process. In the following I brieﬂy review what we currently know about the occurrence rate of planets around intermediate mass stars, before discussing recent results from Herbig Ae/Be stars in the context of planet formation. The main emphasis is put on spatially resolved polarized light images of potentially planet forming disks and how these images - in combination with other data - can be used to empirically constrain (parts of) the planet formation process. Of particular interest are two objects, HD100546 and HD169142, where, in addition to intriguing morphological structures in the disks, direct observational evidence for (very) young planets has been reported. I conclude with an outlook, what further progress we can expect in the very near future with the next generation of high-contrast imagers at 8-m class telescopes and their synergies with ALMA. Accepted by Astrophysics and Space Science as invited short review in special issue about Herbig Ae/Be stars http://arxiv.org/pdf/1504.04880

Conﬁrmation and characterization of the protoplanet HD100546 b - Direct evidence for gas giant planet formation at 50 au Sascha P. Quanz1, Adam Amara1, Michael R. Meyer1, Julien H. Girard2, Matthew A. Kenworthy3 and

32 Markus Kasper4 1 ETH Zurich, Institute for Astronomy, Wolfgang-Pauli-Strasse, 8053 Zurich, Switzerland 2 European Southern Observatory, Alonso de Córdova 3107, Vitacura, Cassilla 19001, Santiago, Chile 3 Sterrewacht Leiden, P.O. Box 9513, Niels Bohrweg 2, 2300 RA Leiden, The Netherlands 4 European Southern Observatory, Karl Schwarzschild Strasse, 2, 85748 Garching bei München, Germany E-mail contact: sascha.quanz at astro.phys.ethz.ch We present the first multi-wavelength, high-contrast imaging study confirming the protoplanet embedded in the disk around the Herbig Ae/Be star HD100546. The object is detected at L′ (∼ 3.8 µm) and M ′ (∼ 4.8 µm), but not at Ks (∼ 2.1 µm), and the emission consists of a point source component surrounded by spatially resolved emission. For the point source component we derive apparent magnitudes of L′ = 13.92 ± 0.10 mag, M ′ = 13.33 ± 0.16 mag, ′′ ◦ and Ks > 15.43 ± 0.11 mag (3σ limit), and a separation and position angle of (0.457 ± 0.014) and (8.4 ± 1.4) , and (0.472 ± 0.014)′′ and (9.2 ± 1.4)◦ in L′ and M ′, respectively. We demonstrate that the object is co-moving with HD100546 and can reject any (sub-)stellar fore-/background object. Fitting a single temperature blackbody to the +193 observed fluxes of the point source component yields an effective temperature of Teff = 932−202 K and a radius +2.7 +0.6 · −4 for the emitting area of R = 6.9−2.9 RJupiter. The best-fit luminosity is L = (2.3−0.4) 10 L⊙. We quantitatively compare our findings with predictions from evolutionary and atmospheric models for young, gas giant planets, discuss the possible existence of a warm, circumplanetary disk, and note that the de-projected physical separation from the host star of (53 ± 2) au poses a challenge standard planet formation theories. Considering the suspected existence of an additional planet orbiting at ∼13–14 au, HD100546 appears to be an unprecedented laboratory to study the formation of multiple gas giant planets empirically. Accepted by ApJ http://arxiv.org/pdf/1412.5173

13 Sensitive survey for CO, CN, H2CO, and SO in the disks of T Tauri and Herbig Ae stars II: Stars in ρ Oph and Upper Scorpius L. Reboussin1,2, S. Guilloteau1,2, M. Simon3, N. Grosso4, V. Wakelam1,2, E. Di Folco1,2, A. Dutrey1,2 and V. Piétu5 1 Universitéde Bordeaux, LAB, UMR 5804, F-33270, Floirac, France 2 CNRS, LAB, UMR 5804, F-33270, Floirac, France 3 Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA 4 Observatoire Astronomique de Strasbourg, Universitéde Strasbourg, CNRS, UMR 7550, 11 rue de l’Université, 6700 Strasbourg, France 5 IRAM, 300 rue de la piscine, F-38406, Saint Martin d’Hères, France E-mail contact: laura.reboussin at obs.u-bordeaux1.fr We attempt to determine the molecular composition of disks around young low-mass stars in the ρ Oph region and to compare our results with a similar study performed in the Taurus-Auriga region. We used the IRAM 30 m telescope to perform a sensitive search for CN N=2-1 in 29 T Tauri stars located in the ρ Oph and upper Scorpius regions. 13CO J=2-1 is observed simultaneously to provide an indication of the level of confusion with the surrounding molecular 17 cloud. The bandpass also contains two transitions of ortho-H2CO, one of SO, and the C O J=2-1 line, which provides complementary information on the nature of the emission. Contamination by molecular cloud in 13CO and even C17O is ubiquitous. The CN detection rate appears to be lower than for the Taurus region, with only four sources being detected (three are attributable to disks). H2CO emission is found more frequently, but appears in general to be due to the surrounding cloud. The weaker emission than in Taurus may suggest that the average disk size in the ρ Oph region is smaller than in the Taurus cloud. Chemical modeling shows that the somewhat higher expected disk temperatures in ρ Oph play a direct role in decreasing the CN abundance. Warmer dust temperatures contribute to convert CN into less volatile forms. In such a young region, CN is no longer a simple, sensitive tracer of disks, and observations with other tracers and at high enough resolution with ALMA are required to probe the gas disk population. Accepted by A&A http://arxiv.org/pdf/1504.04542

33 Chemistry in Protoplanetary Disks: the gas-phase CO/H2 ratio and the Carbon reservoir L. Reboussin1,2, V. Wakelam1,2, S. Guilloteau1,2, F. Hersant1,2 and A. Dutrey1,2 1 Universitéde Bordeaux, LAB, UMR 5804, F-33270, Floirac, France 2 CNRS, LAB, UMR 5804, F-33270, Floirac, France E-mail contact: laura.reboussin at obs.u-bordeaux1.fr The gas mass of protoplanetary disks, and the gas-to-dust ratio, are two key elements driving the evolution of these disks and the formation of planetary system. We explore here to what extent CO (or its isotopologues) can be used as a tracer of gas mass. We use a detailed gas-grain chemical model and study the evolution of the disk composition, starting from a dense pre-stellar core composition. We explore a range of disk temperature profiles, cosmic rays ionization rates, and disk ages for a disk model representative of T Tauri stars. At the high densities that prevail in disks, we find that, due to fast reactions on grain surfaces, CO can be converted to less volatile forms (principally s-CO2, and to a lesser extent s-CH4) instead of being evaporated over a wide range of temperature. The canonical gas-phase abundance of 10−4 is only reached above about 30-35 K. The dominant Carbon bearing entity depends on the temperature structure and age of the disk. The chemical evolution of CO is also sensitive to the cosmic rays ionization rate. Larger gas phase CO abundances are found in younger disks. Initial conditions, such as parent cloud age and density, have a limited impact. This study reveals that CO gas-phase abundance is heavily dependent on grain surface processes, which remain very incompletely understood so far. The strong dependence on dust temperature profile makes CO a poor tracer of the gas-phase content of disks. Accepted by A&A http://arxiv.org/pdf/1505.01309

A Catalog of Point Sources Towards NGC 1333 L. M. Rebull1 1 Infrared Science Archive (IRSA) and Spitzer Science Center (SSC), Infrared Processing and Analysis Center (IPAC) E-mail contact: rebull at ipac.caltech.edu I present a catalog of point source objects towards NGC 1333, resolving a wide variety of confusion about source names (and occasionally positions) in the literature. I incorporate data from optical to radio wavelengths, but focus most of the eﬀort on being complete and accurate from J (1.25 µm) to 24 µm. The catalog encompasses 52◦

HH 666: Different kinematics from Hα and [Fe II] emission provide a missing link between jets and outflows Megan Reiter1, Nathan Smith1, Megan M. Kiminki1, and John Bally2 1 Steward Observatory, University of Arizona, Tucson, 933 N. Cherry Ave, Tucson, AZ 85721, USA 2 Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309, USA E-mail contact: mreiter at as.arizona.edu HH 666 is an externally irradiated protostellar outflow in the Carina Nebula for which we present new near-IR [Fe II] spectra obtained with the FIRE spectrograph at Magellan Observatory. Earlier Hα and near-IR [Fe II] imaging revealed that the two emission lines trace substantially different morphologies in the inner ∼40′′ of the outflow. Hα

34 traces a broad cocoon that surrounds the collimated [Fe II] jet that extends throughout the parent dust pillar. New spectra show that this discrepancy extends to their kinematics. Near-IR [Fe II] emission traces steady, fast velocities of ±200 km s−1 from the eastern and western limbs of the jet. We compare this to a previously published Hα spectrum that reveals a Hubble-flow velocity structure near the jet-driving source. New, second-epoch HST/ACS Hα images reveal the lateral spreading of the Hα outflow lobe away from the jet axis. Hα proper motions also indicate a sudden increase in the mass-loss rate ∼1000 yr ago, while steady [Fe II] emission throughout the inner jet suggests that the burst is ongoing. An accretion burst sustained for ∼1000 yr is an order of magnitude longer than expected for FU Orionis outbursts, but represents only a small fraction of the total age of the HH 666 outflow. Altogether, available data suggests that [Fe II] traces the highly collimated protostellar jet while Hα traces the entrained and irradiated outflow. HH 666 appears to be a missing link between bare jets seen in H II regions and entrained molecular outflows seen from embedded protostars in more quiescent regions. Accepted by MNRAS http://arxiv.org/pdf/1504.00669

Near-Infrared Variability in the Orion Nebula Cluster Thomas S. Rice1, Bo Reipurth2, Scott J. Wolk3, Luiz Paulo Vaz4, and N. J. G. Cross5 1 Department of Astronomy, University of Michigan, 311 West Hall, 1085 South University Avenue, Ann Arbor, MI 48109, USA 2 Institute for Astronomy at Manoa and NASA Astrobiology Institute, University of Hawaii, 640 N. Aohoku Place, Hilo, HI 96720, USA 3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 4 Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, C.P. 702, 30.123-970, Belo Horizonte, MG, Brazil 5 Scottish Universities Physics Alliance, Institute for Astronomy, School of Physics, University of Edinburgh, Royal Observatory, Blackford hill, Edinburgh, EH( 3HJ, UK E-mail contact: tsrice at umich.edu Using the United Kingdom Infrared Telescope on Mauna Kea, we have carried out a new near-infrared J, H, K monitoring survey of almost a square degree of the star-forming Orion Nebula Cluster with observations on 120 nights over three observing seasons, spanning a total of 894 days. We monitored ∼15,000 stars down to J∼20 using the WFCAM instrument, and have extracted 1203 significantly variable stars from our data. By studying variability in young stellar objects (YSOs) in the H–K, K color-magnitude diagram, we are able to distinguish between physical mechanisms of variability. Many variables show color behavior indicating either dust-extinction or disk/accretion activity, but we find that when monitored for longer periods of time, a number of stars shift between these two variability mechanisms. Further, we show that the intrinsic timescale of disk/accretion variability in young stars is longer than that of dust-extinction variability. We confirm that variability amplitude is statistically correlated with evolutionary class in all bands and colors. Our investigations of these 1203 variables have revealed 73 periodic AA Tau type variables, many large-amplitude and long-period (P > 15 day) YSOs, including three stars showing widely- spaced periodic brightening events consistent with circumbinary disk activity, and four new eclipsing binaries. These phenomena and others indicate the activity of long-term disk/accretion variability processes taking place in young stars. We have made the light curves and associated data for these 1203 variables available online. Accepted by Astron. J. http://arxiv.org/pdf/1505.01495

On shocks driven by high-mass planets in radiatively ineﬃcient disks. I. Two-dimensional global disk simulations Alexander J.W. Richert1,2,3,4, Wladimir Lyra3,4,5, Aaron Boley6, Mordecai-Mark Mac Low7, Neal Turner3 1 Department of Astronomy & Astrophysics, Penn State University, 525 Davey Lab, University Park, PA 16802, USA 2 Center for Exoplanets & Habitable Worlds, Pennsylvania State University

35 3 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA, 91109, USA 4 Division of Geological & Planetary Sciences, California Institute of Technology, 1200 E California Blvd MC 150-21, Pasadena, CA 91125 USA 5 Sagan Fellow 6 Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada 7 Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA E-mail contact: ajr327 at psu.edu Recent observations of gaps and non-axisymmetric features in the dust distributions of transition disks have been interpreted as evidence of embedded massive protoplanets. However, comparing the predictions of planet-disk interaction models to the observed features has shown far from perfect agreement. This may be due to the strong approximations used for the predictions. For example, spiral arm fitting typically uses results that are based on low-mass planets in an isothermal gas. In this work, we describe two-dimensional, global, hydrodynamical simulations of disks with embedded protoplanets, with and without the assumption of local isothermality, for a range of planet-to-star mass ratios 1–10 Mjup for a 1 M⊙ star. We use the Pencil Code in polar coordinates for our models. We find that the inner and outer spiral wakes of massive protoplanets (M > 5 Mjup) produce significant shock heating that can trigger buoyant instabilities. These drive sustained turbulence throughout the disk when they occur. The strength of this effect depends strongly on the mass of the planet and the thermal relaxation timescale; for a 10 Mjup planet embedded in a thin, purely adiabatic disk, the spirals, gaps, and vortices typically associated with planet-disk interactions are disrupted. We find that the effect is only weakly dependent on the initial radial temperature profile. The spirals that form in disks heated by the effects we have described may fit the spiral structures observed in transition disks better than the spirals predicted by linear isothermal theory. Accepted by ApJ http://arxiv.org/pdf/1504.00066

Herschel SPIRE-FTS observations of RCW 120 J.A. Rodón1,2, A. Zavagno2, J.-P. Baluteau2, E. Habart3, M. Köhler3, J. Le Bourlot4, F. Le Petit4, and A. Abergel3 1 European Southern Observatory, Alonso de Córdova 3107, Vitacura, Santiago 19, Chile 2 Aix Marseille université, CNRS, Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388 Marseille, France 3 Institut d’Astrophysique Spatiale, CNRS/UniversitéParis-Sud 11, 91405 Orsay, France 4 LUTH, Observatoire de Paris et Universite Paris 7, 5 Place Jules Janssen, F-92190 Meudon, France E-mail contact: jrodon at eso.org The expansion of Galactic HII regions can trigger the formation of a new generation of stars. However, little is know about the physical conditions that prevail in these regions. We study the physical conditions that prevail in specific zones towards expanding HII regions that trace representative media such as the photodissociation region, the ionized region, and condensations with and without ongoing star formation. We use the SPIRE Fourier Transform Spectrometer (FTS) on board Herschel to observe the HII region RCW 120. Continuum and lines are observed in the 190–670 µm range. Line intensities and line ratios are obtained and used as physical diagnostics of the gas. We used the Meudon PDR code and the RADEX code to derive the gas density and the radiation field at nine distinct positions including the PDR surface and regions with and without star-formation activity. For the different regions we detect the atomic lines [NII] at 205 µm and [CI] at 370 and 609 µm, the 12CO ladder between the J=4 and J=13 levels and the 13CO ladder between the J=5 and J=14 levels, as well as CH+ in absorption. We find gas temperatures 4 6 −3 22 −2 in the range 45–250K for densities of 10 –10 cm , and a high column density on the order of NH ∼ 10 cm that is in agreement with dust analysis. The ubiquitousness of the atomic and CH+ emission suggests the presence of a low-density PDR throughout RCW 120. High-excitation lines of CO indicate the presence of irradiated dense 20 structures or small dense clumps containing young stellar objects, while we also find a less dense medium (NH ∼ 10 cm−2) with high temperatures (80–200K). Accepted by A&A http://arxiv.org/pdf/1504.06485

36 The Kinematic and Chemical Properties of a Potential Core-Forming Clump: Perseus B1-E S.I. Sadavoy1, Y. Shirley2,1, J. Di Francesco3, Th. Henning1, M.J. Currie4, Ph. André5, S. Pezzuto6 1 Max-Planck-Institut für Astronomie (MPIA), Königstuhl 17, D-69117 Heidelberg, Germany 2 Astronomy Department, The University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USA 3 National Research Council Canada, 5071 West Saanich Road, Victoria BC Canada, V9E 2E7 4 Joint Astronomy Centre, 660 N. Aóh¯ok¯uPlace, University Park, Hilo, Hawaii, 96720, USA 5 Laboratoire AIM, CEA/DSM-CNRS-UniversitéParis Diderot, IRFU/Service dAstrophysique, Saclay, 91191 Gifsur- Yvette, France 6 Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, 00133, Rome, Italy E-mail contact: sadavoy at mpia.de We present 13CO and C18O (1–0), (2–1), and (3–2) maps towards the core-forming Perseus B1-E clump using observations from the James Clerk Maxwell Telescope (JCMT), Submillimeter Telescope (SMT) of the Arizona Radio Observatory, and IRAM 30 m telescope. We find that the 13CO and C18O line emission both have very complex velocity structures, indicative of multiple velocity components within the ambient gas. The (1–0) transitions reveal a radial velocity gradient across B1-E of 1 km s−1 pc−1 that increases from north-west to south-east, whereas the majority of the Perseus cloud has a radial velocity gradient increasing from south-west to north-east. In contrast, we see no evidence of a velocity gradient associated with the denser Herschel-identified substructures in B1-E. Addition- ally, the denser substructures have much lower systemic motions than the ambient clump material, which indicates that they are likely decoupled from the large-scale gas. Nevertheless, these substructures themselves have broad line widths (0.4 km s−1) similar to that of the C18O gas in the clump, which suggests they inherited their kinematic properties from the larger-scale, moderately dense gas. Finally, we find evidence of C18O depletion only toward one substructure, B1-E2, which is also the only object with narrow (transonic) line widths. We suggest that as prestellar cores form, their chemical and kinematic properties are linked in evolution, such that these objects must first dissipate their turbulence before they deplete in CO. Accepted by ApJ http://arxiv.org/pdf/1504.05206

High spectral and spatial resolution observations of the PDR emission in the NGC2023 reflection nebula with SOFIA and APEX G. Sandell1, B. Mookerjea2, R. Gusten3, M. A. Requena-Torres3, D. Riquelme3 and Y. Okada4 1 SOFIA/USRA, NASA Ames Research Center, MS 232-12, Building N232, Rm. 146, PO Box 1, Moffett Field, CA 94035-0001, USA 2 Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India 3 Max Planck Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany 4 I. Physikalisches Institut der Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany E-mail contact: gsandell at sofia.usra.edu We have mapped the NGC 2023 reflection nebula in [C ii] and CO(11–10) with the heterodyne receiver GREAT on SOFIA and obtained slightly smaller maps in 13CO(3–2), CO(3–2), CO(4–3), CO(6–5), and CO(7–6) with APEX in Chile. We use these data to probe the morphology, kinematics, and physical conditions of the C ii region, which is ionized by FUV radiation from the B2 star HD 37903. The [C ii] emission traces an ellipsoidal shell-like region at a position angle of ∼ −50◦, and is surrounded by a hot molecular shell. In the southeast, where the C ii region expands into a dense, clumpy molecular cloud ridge, we see narrow and strong line emission from high-J CO lines, which comes from a thin, hot molecular shell surrounding the [C ii] emission. The [C ii] lines are broader and show photo evaporating gas flowing into the C ii region. Based on the strength of the [13C ii] F=2–1 line, the [C ii] line appears to be somewhat optically thick over most of the nebula with an optical depth of a few. We model the physical conditions of the surrounding molecular cloud and the PDR emission using both RADEX and simple PDR models. The temperature of the CO emitting PDR shell is ∼ 90 – 120 K, with densities of 105 – 106 cm−3, as deduced from RADEX modeling. Our PDR modeling indicates that the PDR layer where [C ii] emission dominates has somewhat lower densities, 104 to a few times 105 cm−3.

37 Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1504.03745

The young low-mass star ISO-Oph-50: Extreme variability induced by a clumpy, evolving circumstellar disk Alexander Scholz1, Koraljka Muzić2, Vincent Geers3 1 School of Physics and Astronomy, University of St. Andrews, The North Haugh, St. Andrews, Fife, KY16 9SS, United Kingdom 2 European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Santiago 19001, Chile 3 UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh, EH9 3HJ, United Kingdom E-mail contact: as110 at st-andrews.ac.uk ISO-Oph-50 is a young low-mass object in the ∼1 Myr old Ophiuchus star forming region undergoing dramatic changes in its optical/near/mid-infrared brightness by 2–4 mag. We present new multi-band photometry and near-infrared spectra, combined with a synopsis of the existing literature data. Based on the spectroscopy, the source is confirmed as a mid M dwarf, with evidence for ongoing accretion. The near-infrared lightcurves show large-scale variations, with 2–4 mag amplitude in the bands IJHK, with the object generally being bluer when faint. Near its brightest state, the object shows colour changes consistent with variable extinction of ∆AV ∼ 7 mag. High-cadence monitoring at 3.6 µm reveals quasi-periodic variations with a typical timescale of 1–2 weeks. The best explanation for these characteristics is a low-mass star seen through circumstellar matter, whose complex variability is caused by changing inhomogeneities in the inner parts of the disk. When faint, the direct stellar emission is blocked; the near-infrared radiation is dominated by scattered light. When bright, the emission is consistent with a photosphere strongly reddened by circumstellar dust. Based on the available constraints, the inhomogeneities have to be located at or beyond ∼0.1 AU distance from the star. If this scenario turns out to be correct, a major portion of the inner disk has to be clumpy, structured, and/or in turmoil. In its observational characteristics, this object resembles other types of YSOs with variability caused in the inner disk. Compared to other objects, however, ISO-Oph-50 is clearly an extreme case, given the large amplitude of the brightness and colour changes combined with the erratic behaviour. ISO-Oph-50 has been near its brightest state since 2013; further monitoring is highly encouraged. Accepted by MNRAS http://arxiv.org/pdf/1504.03568

Evolution of column density distributions within Orion A A. M. Stutz1 and J. Kainulainen1 1 MPIA, Heidelberg, Germany E-mail contact: stutz at mpia.de We compare the structure of star–forming molecular clouds in different regions of Orion A to determine how the column density probability distribution function (N–PDF) varies with environmental conditions such as the fraction of young protostars. A correlation between the N–PDF slope and Class 0 protostar fraction has been previously observed in a low-mass star–formation region (Perseus) by Sadavoy; here we test if a similar correlation is observed in a high–mass star–forming region. We use Herschel PACS and SPIRE cold dust emission observations to derive a column density map of Orion A. We use the Herschel Orion Protostar Survey (HOPS) catalog for accurate identification and classification of the Orion A young stellar object (YSO) content, including the cold and relatively short–lived Class 0 protostars (with a ∼ 0.14 Myr lifetime). We divide Orion A into eight independent 0.25 square degree (13.5 pc2) regions; in each region we fit the N–PDF distribution with a power–law, and we measure the fraction of Class 0 protostars. We use a maximum likelihood method to measure the N–PDF power–law index without binning the column density data. We find that the Class 0 fraction is higher in regions with flatter column density distributions. We test the effects of incompleteness, extinction–driven misclassification of Class 0 sources, resolution, and adopted pixel–scales. We show that these effects cannot account for the observed trend. Our observations demonstrate an association between the slope of the power–law N–PDF and the Class 0 fractions within Orion A. Various interpretations are discussed

38 including timescales based on the Class 0 protostar fraction assuming a constant star–formation rate. The observed relation suggests that the N–PDF can be related to an “evolutionary state” of the gas. If universal, such a relation permits an evaluation of the evolutionary state from the N–PDF power–law index at much greater distances than those accesible with protostar counts. Accepted by A&A Letters http://arxiv.org/pdf/1504.05188

Constraining the abundances of complex organics in the inner regions of solar-type protostars Vianney Taquet1,2, Ana Lpez-Sepulcre3,4,5, Cecilia Ceccarelli3,4, Roberto Neri6, Claudine Kahane3,4 and Steven B. Charnley1 1 Astrochemistry Laboratory and The Goddard Center for Astrobiology, Mailstop 691, NASA Goddard Space Flight Center, USA 2 Leiden Observatory, Leiden University, The Netherlands 3 Univ. Grenoble Alpes, France 4 CNRS, IPAG, France 5 Department of Physics, The University of Tokyo, Japan 6 Institut de Radioastronomie Millimtrique, Grenoble, France E-mail contact: taquet at strw.leidenuniv.nl The high abundances of Complex Organic Molecules (COMs) with respect to methanol, the most abundant COM, detected toward low-mass protostars, tend to be underpredicted by astrochemical models. This discrepancy might come from the large beam of the single-dish telescopes, encompassing several components of the studied protostar, commonly used to detect COMs. To address this issue, we have carried out multi-line observations of methanol and several COMs toward the two low-mass protostars NGC 1333-IRAS 2A and -IRAS 4A with the Plateau de Bure interferometer at an angular resolution of 2??, resulting in the first multi-line detection of the O-bearing species glycolaldehyde and ethanol and of the N-bearing species ethyl cyanide toward low-mass protostars other than IRAS 16293. The high number of detected transitions from COMs (more than 40 methanol transitions for instance) allowed us to accurately derive the source size of their emission and the COM column densities. The COM abundances with respect to methanol derived toward IRAS 2A and IRAS 4A are slightly, but not substantially, lower than those derived from previous single-dish observations. The COM abundance ratios do not vary significantly with the protostellar luminosity, over five orders of magnitude, implying that low-mass hot corinos are quite chemically rich as high-mass hot cores. Astrochemical models still underpredict the abundances of key COMs, such as methyl formate or di-methyl ether, suggesting that our understanding of their formation remains incomplete. Accepted by The Astrophysical Journal http://iopscience.iop.org/0004-637X/804/2/81/

Gas density drops inside dust cavities of transitional disks around young stars observed with ALMA Nienke van der Marel1, Ewine F. van Dishoeck1,2, Simon Bruderer2, Laura Perez3 and Andrea Isella4 1 Leiden Observatory, P.O. Box 9513, 2300 RA Leiden, the Netherlands 2 MPE, Giessenbachstrasse 1, 85748 Garching, Germany 3 NRAO, P.O. Box O, Socorro, NM 87801, USA 4 Rice University, 6100 Main Street, Houston, TX 77005, USA E-mail contact: nmarel at strw.leidenuniv.nl Transitional disks with large dust cavities are important laboratories to study planet formation and disk evolution. Cold gas may still be present inside these cavities, but the quantiﬁcation of this gas is challenging. The gas content is important to constrain the origin of the dust cavity. We use Atacama Large Millimeter/submillimeter Array (ALMA) observations of 12CO 6–5 and 690 GHz (Band 9) continuum of ﬁve well-studied transitional disks. In addition, we analyze previously published Band 7 observations of a disk in 12CO 3–2 line and 345 GHz continuum. The observations

39 are used to set constraints on the gas and dust surface density profiles, in particular the drop delta-gas of the gas density inside the dust cavity. The physical-chemical modeling code DALI is used to analyze the gas and dust images simultaneously. We model SR21, HD135344B, LkCa15, SR24S and RXJ1615-3255 (Band 9) and J1604-2130 (Band 7). The SED and continuum visibility curve constrain the dust surface density. Subsequently, the same model is used to calculate the 12CO emission, which is compared with the observations through spectra and intensity cuts. The amount of gas inside the cavity is quantified by varying the delta-gas parameter. Model fits to the dust and gas indicate that gas is still present inside the dust cavity for all disks but at a reduced level. The gas surface density drops inside the cavity by at least a factor 10, whereas the dust density drops by at least a factor 1000. Disk masses are comparable with previous estimates from the literature, cavity radii are found to be smaller than in the 345 GHz SubMillimeter Array (SMA) data. The derived gas surface density profiles suggest clearing of the cavity by one or more companions in all cases, trapping the millimeter-sized dust at the edge of the cavity. Accepted by A&A http://arxiv.org/pdf/1504.03927

Investigating the rotational evolution of young, low-mass stars using Monte Carlo simulations Maria Jaqueline Vasconcelos1,2 and Jerome Bouvier2 1 LATO/DCET - UESC, Rodovia Jorge Amado, km 16, Ilhéus, 45662-900 - Brazil 2 Univ. Grenoble Alpes, IPAG, F-38000 Grenoble, France CNRS, IPAG, F-38000 Grenoble, France E-mail contact: mjvasc at uesc.br Young stars rotate well below break-up velocity, which is thought to result from the magnetic coupling with their accretion disk. We investigate the rotational evolution of young stars under the disk-locking hypothesis through Monte Carlo simulations. Our simulations included 280,000 stars, each of which was initially assigned a mass, a rotational period, and a mass accretion rate. The mass accretion rate depends on both mass and time, following power-law indices of 1.4 and -1.5, respectively. A mass-dependent accretion threshold was defined below which a star was considered as diskless, which resulted in a distribution of disk lifetimes that matches observations. Stars were evolved at constant angular spin rate while accreting and at constant angular momentum when they became diskless. Starting with a bimodal distribution of periods for disk and diskless stars, we recovered the bimodal period distribution seen in several young clusters. The short-period peak mostly consists of diskless stars, and the long-period peak is mainly populated by accreting stars. Both distributions, however, present a long tail toward long periods, and a population of slowly rotating diskless stars is observed at all ages. We reproduced the observed correlations between disk fraction and spin rate, as well as between IR excess and rotational period. The period-mass relation we derived from the simulations only shows the same global trend as observed in young clusters when we released the disk-locking assumption for the lowest mass stars. Finally, we find that the time evolution of median specific angular momentum follows a power-law index of -0.65 for accreting stars, as expected from disk locking, and of -0.53 for diskless stars, a shallower slope that results from a wide distribution of disk lifetimes. At the end of the accretion phase, our simulations reproduce the angular momentum distribution of the low-mass members of the 13 Myr h Per cluster. Using observationally documented distributions of disk lifetimes, mass accretion rates, and initial rotation periods, and evolving an initial population from 1 to 12 Myr, we reproduced the main characteristics of pre-main sequence angular momentum evolution, which supports the disk-locking hypothesis. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1504.04717

Strong effect of the cluster environment on the size of protoplanetary discs? Kirsten Vincke1, Andreas Breslau1 and Susanne Pfalzner1 1 Max Planck Institute for Radio Astronomy, Auf dem Hügel 69, 53121 Bonn, Germany E-mail contact: kvincke at mpifr-bonn.mpg.de Context. Most stars are born in clusters, thus the protoplanetary discs surrounding the newly formed stars might be influenced by this environment. Isolated star-disc encounters have previously been studied, and it was shown that

40 very close encounters are necessary to completely destroy discs. However, relatively distant encounters are still able to change the disc size considerably. Aims. We quantify the importance of disc-size reduction that is due to stellar encounters in an entire stellar population. Method. We modelled young, massive clusters of different densities using the code Nbody6 to determine the statistics of stellar encounter parameters. In a second step, we used these parameters to investigate the effect of the environments on the disc size. For this purpose, we performed a numerical experiment with an artificial initial disc size of 105 AU. Results. We quantify to which degree the disc size is more sensitive to the cluster environment than to the disc mass or frequency. We show that in all investigated clusters a large portion of discs is significantly reduced in size. After 5 Myr, the fraction of discs smaller than 1000 AU in ONC-like clusters with an average number density of ∼ 60 pc−3, the fraction of discs smaller than 1000 AU is 65%, while discs smaller than 100 AU make up 15%. These fractions increase to 84% and 39% for discs in denser clusters like IC 348 (∼ 500 pc−3). Even in clusters with a density four times lower than in the ONC (∼ 15 pc−3), about 43% of all discs are reduced to sizes below 1000 AU and roughly 9% to sizes below 100 AU. Conclusions. For any disc in the ONC that initially was larger than 1000 AU, the probability to be truncated to smaller disc sizes as a result of stellar encounters is quite high. Thus, among other effects, encounters are important in shaping discs and potentially forming planetary systems in stellar clusters. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1504.06092

Spectro-astrometry of LkCa 15 with X-Shooter: Searching for emission from LkCa 15b E.T. Whelan1, N. Huélamo2, J.M. Alcalá3,J. Lillo-Box2, H. Bouy2, D. Barrado2, J. Bouvier4,5, and B. Mer´ın6 1 Institut für Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Eberhard Karls Universität, 72076 Tübingen, Germany 2 Centro de Astrobiolog´ıa, INTA-CSIC, Depto Astrof´ısica, European Space Astronomy Cente (ESAC) Campus, PO Box 78, 28691, Villanueva de la Cañada, Madrid, Spain 3 INAF-Osservatorio Astronomico di Capodimonte, via Moiariello, 16, I-80131, Napoli, Italy 4 Univ. Grenoble Alpes, IPAG, F-38000 Grenoble, France 5 CNRS, IPAG, F-38000 Grenoble, France 6 European Space Astronomy Center (ESAC), P.O. box 78, 28691, Villanueva de la Caada, Madrid, Spain E-mail contact: emma.whelan at astro.uni-tuebingen.de Planet formation is one explanation for the partial clearing of dust observed in the disks of some T Tauri stars. Indeed studies using state-of-the-art high angular resolution techniques have very recently begun to observe planetary companions in these so-called transitional disks. The goal of this work is to use spectra of the transitional disk object LkCa 15 obtained with X-Shooter on the Very Large Telescope to investigate the possibility of using spectro-astrometry to detect planetary companions to T Tauri stars. It is argued that an accreting planet should contribute to the total emission of accretion tracers such as Hα and therefore planetary companions could be detected with spectro-astrometry in the same way as it has been used to detect stellar companions to young stars. A probable planetary-mass companion was recently detected in the disk of LkCa 15. Therefore, it is an ideal target for this pilot study. We studied several key accretion lines in the wavelength range 300 nm to 2.2 µm with spectro-astrometry. While no spectro-astrometric signal is measured for any emission lines the accuracy achieved in the technique is used to place an upper limit on the contribution of the planet to the flux of the Hα, Paγ, and Paβ lines. The derived upper limits on the flux allows an upper limit of the mass accretion rate, log(M˙ acc) = −8.9 to −9.3 for the mass of the companion between 6 MJup and 15 MJup, respectively, to be estimated (with some assumptions). Accepted by A&A http://arxiv.org/pdf/1504.04824

41 New Jobs

New Faculty Position in Galactic or Extragalactic Star Formation at Universidad de Chile

The Universidad de Chile Department of Astronomy (DAS) invites applications for a tenure track position at the assistant professor level beginning no later than September 2016. We are primarily interested in candidates with a proven record of independent research in the area of star formation, in the Galactic and/or extragalactic fields. In particular, we seek candidates who can make effective use of the 10% of ALMA time available to astronomers working in Chilean institutions. The successful candidate is expected to join the activities of the DAS, including carrying out an original research program involving graduate students and postdocs, and teaching at the graduate and undergraduate levels. Graduate level teaching is often conducted in English, however, candidates are expected to teach undergraduate courses in Spanish after 1 year of arrival. Spanish courses for foreigners are offered for free by the University. Our department is one of the leading –and the oldest– astronomy centers in Chile, fostering an engaging and productive international community composed of 22 faculty, 15 postdoctoral researchers, and 30 graduate students. The DAS hosts many international programs including the French UMI-FCA, the Chinese CASSACA (www.cassaca.org), and other major science and technology grants (see www.das.uchile.cl/web en/das proyectos.html). The successful applicant will have access to the 10% of telescope time guaranteed to Chilean institutions on all observatories in the country, including the future GMT and E-ELT (see www.das.uchile.cl/das cntac.html). Super- computing facilities are available both locally and through the National Laboratory for High Performance Computing (www.nlhpc.cl). Interested applicants should submit a curriculum vitae, a list of publications, a statement of previous research (3 page limit), a research plan (5 page limit), and a description of teaching interests (1 page). At least three letters of reference should be sent directly to the recruiting committee. All materials must be emailed to [email protected]. Review of the applications will commence on July 1st, 2015 and will continue until the position is filled. We expect to have a short list by the end of September and to make an offer before the end of November 2015. For enquiries, please contact Diego Mardones, chair of the recruiting committee, at [email protected]. Santiago is a growing metropolis with excellent global communications and a high standard of living. The DAS is located in a beautiful part of the city, site of the old National Observatory. The compensation package includes a competitive salary, moving expenses, and housing benefits. Chilean law includes six months of paid parental leave for mothers. Universidad de Chile is an equal opportunity employer committed to excellence through diversity. We encourage applications from all nationalities and from under-represented groups in science.

42 Postdoctoral and PhD position in protoplanetary/debris discs or evolved stars with planets at the UAM, Madrid, Spain

Applications are invited for a 2-year postdoctoral position (1+1yr after positive evaluation) and a 4-year PhD position at the Department of Theoretical Physics from the Universidad Autónoma de Madrid (UAM). The successful candidates will be hired under the project ”From stones to planets and back to rocks: understanding planet formation and destruction” (AYA2014-55840-P), lead by Eva Villaver and Gwendolyn Meeus and funded by the Spanish National Plan of R&D. The research will depend on the experience of the candidate, but should focus on either: - How the structure of protoplanetary and debris discs depends on the presence of planets. - How stellar evolution affects the architecture of planetary systems. The methods can either be observational or theoretical. For the postdoctoral position, we are seeking a highly motivated researcher with experience in some of the following areas: protoplanetary or debris disc modelling, stellar evolution, detection of planets, or high spatial/spectral resolution disc observations (e.g. with ALMA, SPHERE or NACO). Postdoctoral applicants must have obtained their PhD in Astrophysics or Physics and have a doctoral certificate at the moment of appointment, while the doctoral candidate must have a Master in Astrophysics or Physics at that time. Ideally the position will start in fall of 2015, but a later start is also possible. Applicants should send their CV with publication list, along with a cover letter briefly describing research interests and achievements, and arrange for two recommendation letters to be sent to [email protected] and [email protected] by July 20th, 2015. The contracts include medical insurance under the Spanish National Health Service which also cover your accompanying partner and children, if relevant. Our group is also a host for Marie S. Curie fellowships, and can provide administrative support for those wishing to apply. Located in Madrid, Spain, the Department of Theoretical Physics at UAM offers a rich atmosphere in front-line physics research, ranging from Particle Physics (both theoretical and experimental), Nuclear Physics, Neuroscience, Experimental High-Energy Physics, to Astrophysics. The Astrophysics group at the department carries out research on Cosmology, Galactic and Extra-galactic Astrophysics, and runs a Master PhD program in Astrophysics. Fur- ther information about UAM’s Department of Theoretical Physics is available via the Internet on the UAM Web page (www.ft.uam.es). Close collaboration with the Centre for Astrobiology (CAB) and the ESA European Space Astronomy Centre (ESAC), also located in Madrid, is ongoing.

PhD position on the origin of the IMF Vienna, Austria

Given our group’s recent success in calibrating ESA Herschel Space Observatory data and constructing robust and large-scale column density and temperature maps of nearby stellar nurseries, we are looking for a PhD candidate to explore the possible link between molecular cloud structure and the origin of the stellar Initial Mass Function (IMF). The candidate will work on a robust definition of a dense core, the ’stellar embryo’, a fundamental but hard to define astrophysical object, as well as on the optimal extraction techniques from large scale dust continuum maps and core population statistics. We are looking for a highly motivated PhD student with a good knowledge of image analysis and statistics (preferably with open source tools, e.g., Python, R) and familiarity with interstellar cloud research. The Department of Astrophysics of the University of Vienna offers a stimulating research environment with staff working in various areas of astrophysics. The department is involved in the major observatories of ESO (VLT and E-ELT) and ESA/JAXA/NASA (Gaia, Spica, Plato, Euclid, JWST). The city of Vienna, where E. Salpeter was born, scored highest worldwide for overall quality of living for 4 consecutive years according to Mercer’s survey (2010-2014). Review of applications starts Jun 1st, 2015 and will continue until the position is filled. Applications should be sent to Prof. João Alves ([email protected]) and include: 1) CV, 2) a brief description of past research, and 3) two letters of reference.

43 Meetings

From Clouds to Protoplanetary Disks: the Astrochemical Link 5-8 October 2015 Hans Harnack Haus, Berlin, Germany

Recent advances in sub-millimeter (ALMA, NOEMA) and IR (Spitzer, Herschel) observational facilities and modeling have started to shed more light on the physical and chemical processes governing the evolution of interstellar clouds into pre-stellar cores, protostars, protoplanetary disks, and, eventually, planetary systems. Molecular spectroscopy has played a crucial role in these advances, as only lines can unveil the underlying dynamics and can provide information on the physical and chemical structure across clouds, cores and protoplanetary disks. Furthermore, chemo-dynamical models have become more and more detailed, thanks also to the great advances in (gas phase and surface) laboratory work as well as quantum chemistry calculations, while magneto-hydrodynamical simulations have included simplified chemical codes to test theoretical predictions. We believe this is the right moment to try to summarize a current status quo in this exciting field of astronomy, and to facilitate and foster future directions of astrochemistry research. Since astrochemistry is the trait d’union of different communities, the main goal of this well-focussed meeting will be to bring together observers, theoreticians and experimentalists to present their recent advances, to discuss about the main uncertainties and to plan future developments. Interaction between the different communities will be encouraged and mixed, lengthy discussions will be organized at the end of each session, and in the end of each conference’s day. We will particularly encourage young scientists (students, PhD students, post-docs) to participate, with the main aim to help them to shape their knowledge and understanding of modern and forthcoming ideas about details of planet- and star-formation from a cohort of the world-leading experts. Further information can be found on the workshop website: https://cas-events.mpe.mpg.de/astrolink SOC/LOC: Chair: Paola Caselli (MPE Garching München) co-Chair: Dimitry Semenov (MPIA Heidelberg, co-Chair) Christian Endres (MPE Garching München) Leonardo Testi (ESO Garching München) Anton Vasyunin (MPE Garching München) Yuri Aikawa (Kobe Univ., Japan) Henrik Beuther (MPIA Heidelberg, DE) Jrgen Blum (TU Braunschweig, DE) Cecilia Ceccarelli (IPAG, Grenoble, France) Ewine van Dishoeck (Leiden/ESO, NL/DE) Cornelis Dullemond (ITA Heidelberg, DE) Anne Dutrey (LAB, Bordeaux, France) Thomas Henning (MPIA Heidelberg, DE) Eric Herbst (Univ. of Virginia, Charlottesville, USA) Karin Oeberg (Harvard Univ., USA) Nami Sakai (Univ. of Tokio, Japan) Peter Schilke (MPIfR, Bonn, DE) Serena Viti (UCL, London, UK) Organizer: MPE Garching & MPIA Heidelberg The total number of participants is restricted by the available rooms in the Harnack-Haus and will be limited to 120 guests.

44 Cloudy workshop 2015 Sept 21-26 Inter-University Centre for Astronomy and Astrophysics, Pune, India

Registration is now open for the 2015 September Cloudy workshop. It will be held Sept 2126 at the Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune, India Cloudy simulates the microphysics of matter exposed to ionizing radiation. It calculates the atomic physics, chemistry, radiation transport, and dynamics problems simultaneously and self consistently, building from a foundation of individual atomic and molecular processes. The result is a prediction of the conditions in the material and its observed spectrum. The workshop will cover observation, theory, and application of Cloudy to a wide variety of astronomical environments. This includes the theory of diﬀuse non-LTE matter and quantitative spectroscopy, the science of using spectra to make physical measurements. We will use Cloudy to simulate such objects as AGB stars, Active Galactic Nuclei, Starburst galaxies, and the intergalactic medium. The sessions will consist of a mix of textbook study, using Osterbrock & Ferland, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei, application of the spectral-simulation code Cloudy to a variety of astrophysical problems, and projects organized by the participants. No prior experience with Cloudy is assumed. There is no registration fee and ﬁnancial support is not available. See http://cloud9.pa.uky.edu/?gary/cloudy/CloudySummerSchool/ for more information and for information on how to apply.

45 Summary of Upcoming Meetings

Triple Evolution & Dynamics in Stellar and Planetary Systems 31 May - 5 June 2015 Haifa, Israel http://trendy-triple.weebly.com Workshop on the Formation of the Solar System II 2 - 4 June 2015 Berlin, Germany https://indico.mpifr-bonn.mpg/FormationOfTheSolarSystem2 IGM@50: is the Intergalactic medium driving Star Formation? 8 - 12 June 2015 Abbazia di Spineto, Italy http://www.arcetri.astro.it/igm50 The Formation and Destruction of Molecular Clouds 22 - 23 June 2015 Tenerife, Spain http://eas.unige.ch/EWASS2015/session.jsp?id=S6 30 Years of Photodissociation regions - A Symposium to honor David Hollenbach’s lifetime in science 28 June - 3 July 2015 http://pdr30.strw.leidenuniv.nl Gordon Research Conference on Origins of Solar Systems 28 June - 3 July 2015 http://www.grc.org/programs.aspx?id=12345 Disc dynamics and planet formation 29 June - 3 July 2015 Larnaka, Cyprus http://www.star.uclan.ac.uk/discs2015 The Stellar IMF at Low Masses: A Critical Look at Variations and Environmental Dependencies 29 June - 1 July 2015 Baltimore, Maryland, USA http://www.stsci.edu/institute/conference/stellar-imf/ From super-Earths to brown dwarfs: Who’s who 29 June - 3 July 2015 Paris, France http://www.iap.fr/col2015 Orion (un)plugged 1-3 + 6-8 July 2015 Vienna, Austria https://www.univie.ac.at/alveslab/orion_unplugged/ From Interstellar Clouds to Star-forming Galaxies: Universal Processes? 3 - 7 August 2015 http://astronomy2015.org/symposium_315 Cosmic Dust 17 - 21 August 2015 Tokyo, Japan https://www.cps-jp.org/~dust/ 6th Zermatt ISM Symposium: Conditions and Impact of Star Formation - From Lab to Space 7 - 11 September 2015 Zermatt, Switzerland http://www.astro.uni-koeln.de/zermatt2015 Cloudy Workshop 21 - 26 September 2015 Pune, India http://cloud9.pa.uky.edu/?gary/cloudy/CloudySummerSchool/ From Clouds to Protoplanetary Disks: the Astrochemical Link

46 5 - 8 October 2015 Berlin, Germany https://cas-events.mpe.mpg.de/astrolink Exchanging Mass, Momentum and Ideas: Connecting Accretion and Outﬂows in Young Stellar Objects 27 - 29 October 2015 Noordwijk, The Netherlands http://www.cosmos.esa.int/web/accretion-outflow-workshop Extreme Solar Systems III 29 November - 4 December 2015 Hawaii, USA http://ciera.northwestern.edu/Hawaii2015.php From Stars to Massive Stars 6 - 9 April 2016, Gainesville, Florida, USA http://conference.astro.ufl.edu/STARSTOMASSIVE/ The 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun 6 - 10 June 2016 Uppsala, Sweden http://www.coolstars19.com Other meetings: http://www1.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/meetings/

47 Short Announcements

Fizeau exchange visitors program - special call for applications

Dear colleagues! The Fizeau exchange visitors program in optical interferometry funds (travel and accommodation) visits of researchers to an institute of his/her choice (within the European Community) to perform collaborative work and training on one of the active topics of the European Interferometry Initiative. The visits will typically last for one month, and strengthen the network of astronomers engaged in technical, scientific and training work on optical/infrared interferometry. The program is open for all levels of astronomers (Ph.D. students to tenured staff). non-EU based missions will only be funded if considered essential by the Fizeau Committee. Applicants are strongly encouraged to seek also partial support from their home or host institutions. IMPORTANT NOTE: This is a special call to support attendance of the 8th VLTI summer school: http://www.astro.uni-koeln.de/vltischool2015. Therefore no research plan and invitation letter from the host institution are required. The deadline for applications is May 30. Further informations and application forms can be found at www.european-interferometry.eu and vltischool.sciencesconf.org The program is funded by OPTICON/FP7. Please distribute this message also to potentially interested colleagues outside of your community! Looking forward to your applications, Josef Hron & Laszlo Mosoni (for the European Interferometry Initiative) Electronic mail: fi[email protected]

Moving ... ??

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