THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 241 — 12 January 2013 Editor: Bo Reipurth ([email protected]) 1 List of Contents The Star Formation Newsletter Interview ...................................... 3 My Favorite Object ............................ 5 Editor: Bo Reipurth [email protected] Perspective .................................... 7 Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers .......... 10 [email protected] New Jobs ..................................... 42 Technical Assistant: Hsi-Wei Yen Meeting Announcements ...................... 44 [email protected] Upcoming Meetings .......................... 45 Editorial Board Short Announcements ........................ 47 Joao Alves Alan Boss Jerome Bouvier Lee Hartmann Cover Picture Thomas Henning Paul Ho The Cygnus X region is one of the richest known Jes Jorgensen regions of star formation in the Galaxy. Because Charles J. Lada of the high extinction to the region, it is rather Thijs Kouwenhoven unremarkable at optical wavelengths, but in the in- Michael R. Meyer frared the full scale of star formation activity is re- Ralph Pudritz vealed. The image shows a Spitzer mosaic, from Luis Felipe Rodr´ıguez the Spitzer Cygnus X Legacy Survey, of a region Ewine van Dishoeck several pc wide at the assumed distance of 1.7 kpc Hans Zinnecker (blue 3.6 µm, aqua 4.5 µm, green 8 µm, red 24 µm). The pillars and globules face towards the center of The Star Formation Newsletter is a vehicle for the Cygnus OB2 association, which harbors about fast distribution of information of interest for as- a hundred O stars and many thousands of young tronomers working on star and planet formation low mass stars. Several generations of young stars and molecular clouds. You can submit material are found with an age spread from ∼1 Myr to 5- for the following sections: Abstracts of recently 7 Myr. An infrared dark cloud to the upper right accepted papers (only for papers sent to refereed shows ongoing star formation. A stellar wind bub- journals), Abstracts of recently accepted major re- ble surrounds a massive star. views (not standard conference contributions), Dis- sertation Abstracts (presenting abstracts of new Image courtesy Jet Propulsion Laboratory Ph.D dissertations), Meetings (announcing meet- ings broadly of interest to the star and planet for- mation and early solar system community), New Jobs (advertising jobs specifically aimed towards persons within the areas of the Newsletter), and Short Announcements (where you can inform or re- Submitting your abstracts quest information from the community). Addition- ally, the Newsletter brings short overview articles Latex macros for submitting abstracts on objects of special interest, physical processes or and dissertation abstracts (by e-mail to theoretical results, the early solar system, as well [email protected]) are appended to as occasional interviews. each Call for Abstracts. You can also submit via the Newsletter web inter- Newsletter Archive face at http://www2.ifa.hawaii.edu/star- www.ifa.hawaii.edu/users/reipurth/newsletter.htm formation/index.cfm 2 few major problems that astronomers were wrestling with? Ben Zuckerman A: To answer this question, I took a look at my 1974 ARAA article with Pat Palmer. I was only 30 when we in conversation with Bo Reipurth wrote that article on interstellar molecules and recall think- ing how thankful I was that Alan Maxwell had steered me to such a blossoming place in modern astronomy. In the late 1960s the new field of infrared astronomy, along with maser emission from OH and water molecules, en- abled astronomers to peer into the depths of dark clouds – some of which were found to be much more massive than any known previously – right at protostars. Maser sizes could be measured with long baseline interferometers that were just coming into their own then. My 1968 Ph.D. thesis was a study of thermal and maser OH emission. The path from formation of a giant molecular cloud, to fragmentation into clusters of protostars, and then to the mechanisms for collapse of an individual protostar occu- pied the efforts of many of us. The last stages in this chain Q: You spent the first 15 or so years of your research career were accompanied by both accretion and bi-polar mass in radio astronomy. How did that come about? outflow. Tom and Eva Kuiper and I wrote the earliest published paper on an observed, high velocity, molecular A: I began my research in astronomy in 1965 as a grad- outflow, focusing on the Orion molecular cloud behind the uate student at Harvard University. Senior Research As- Orion Nebula. In 1973 I wrote a paper titled ’A model of tronomer Alan Maxwell apparently thought I was floun- the Orion Nebula’ that married massive molecular clouds dering, so he steered me to the radio astronomical research to HII regions in ways that had not previously been done. group of Professor A. Edward Lilley. Ed’s graduate stu- The paper was generally well received and it soon earned dent Ellen Gundermann had just discovered OH maser me an all-expenses paid trip to a memorable meeting at emission as part of her Ph.D. thesis research and Hoglund a ski resort in the Austrian Alps. I was greatly impressed & Mezger had announced in Science the first convincing by how much beer some astronomers could consume with- detection of a radio recombination line (n = 110 → 109) out sliding under the table; Nick Scoville and Eric Becklin from Galactic HII regions. So spectral line radio astron- come to mind. omy was hopping and I was glad to become part of it. During the 1970s discovery and study of interstellar and The interior of the Grand Canyon is my favorite place on circumstellar molecules was rather akin to discovery and Earth. So perhaps it is fitting that one of my favorite study of extrasolar planets now. papers of my nearly 50-year research career was hatched while I was hiking in 1973 in the Canyon with my wife. Q: As regards star formation, what was the observational The issue at hand was how to explain the large velocity situation at the onset of your career? widths of molecular lines seen coming from giant molecular A: In 1965 what we knew about star formation came pri- clouds. Some very smart astronomers, including theorist marily from theory, there was little observational data. Peter Goldreich and an observational team led by Arno Bart Bok (my academic grandfather) found isolated dark Penzias and Bob Wilson, apparently preferred overall free- clouds (’Bok globules’) that could be progenitors to stars, fall collapse of the clouds due to their self-gravity. Peter and George Herbig had identified numerous T Tauri stars and his graduate student John Kwan wrote a lovely paper associated with dark clouds, but the interstellar dust grains explaining the line profiles in this way. placed strict limits on what these optical astronomers could But I was unhappy with this model and, while walking hope to accomplish on the actual star formation process. in the Canyon, hit upon some problems with free-fall col- I remember how people would talk of the North Amer- lapse. At that time I was a visiting researcher at UC ica Nebula as a site of recent star formation, but it was Berkeley and was working with Neal Evans who was Char- only after infrared and radio telescopes were pointed there lie Townes’ graduate student. Neal and I published a 1974 that we all fully appreciated that current star formation paper “Models of Massive Molecular Clouds” that con- was taking place in the dark ’Gulf of Mexico’ and not in tained two principal conclusions: (1) if massive molecular the famous glowing nebula itself. clouds were collapsing at all, then it was at velocities much Q: As observations relevant to star formation began to less than free-fall, and (2) turbulence was the likely mech- catch up with and eventually overtake theory, what were a 3 anism that was slowing the collapse. Conclusion #1 was 2012 my former graduate student Carl Melis led our team accepted quickly by the star formation community. The as we watched a massive extrasolar zodiacal-cloud analog same could not be said for conclusion #2. The unusual ci- mysteriously vanish in a space of only 1.5 years. tation history of our paper illustrates the prevailing ideas Q: You have written a number of ARAA articles. Have in the field over the next nearly 40 years, right up to the these tracked your changing astronomical interests? present day. For decades the favored mechanism to slow cloud collapse was interstellar magnetism and our paper A: I’ve had 4 ARAA articles between 1974 and 2004 and was hardly cited. But, in recent years, turbulence has am not anxious to write any more; they are a lot of work! made a comeback and the situation is still hotly debated I’m happy to say that the first one, on interstellar molecules, today. Our paper was published in 1974 but received, by has had some legs and is still being cited. My 1980 arti- far, its most citations, 38 years later, in 2012. cle on mass loss from red giants appeared shortly before the launch of IRAS, which revolutionized our knowledge Q: In the late 1970s and early 1980s you drifted away from of the field, and soon made my article obsolete. The third the study of interstellar molecular clouds and away from ARAA article, on dusty circumstellar disks, appeared in radio astronomy. Why? 2001 and was in large part a tribute to IRAS. The article A: Some first-rate astronomers have spent their entire ca- appeared shortly before the launch of Spitzer whose re- reers focused on one area of astronomy.