THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 276 — 12 December 2015 Editor: Bo Reipurth ([email protected]) List of Contents The Star Formation Newsletter Interview ...................................... 3 My Favorite Object ............................ 6 Editor: Bo Reipurth [email protected] Perspective ................................... 12 Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers .......... 16 [email protected] Dissertation Abstracts ........................ 56 Technical Assistant: Hsi-Wei Yen New Jobs ..................................... 57 [email protected] Meetings ..................................... 58 Editorial Board Summary of Upcoming Meetings ............. 60 New Books ................................... 61 Joao Alves Alan Boss Jerome Bouvier Lee Hartmann Thomas Henning Paul Ho Cover Picture Jes Jorgensen Charles J. Lada Herschel 36 (the bright star in the center of Thijs Kouwenhoven the image) is here shown in an image from Michael R. Meyer HST. The star is a spectroscopic triple system Ralph Pudritz (O7.5V+O9V+B0.5V) which illuminates and ion- Luis Felipe Rodr´ıguez izes the famous Hourglass Nebula at the center of Ewine van Dishoeck M8. Hans Zinnecker Image courtesy NASA, ESA, J. Trauger (Jet The Star Formation Newsletter is a vehicle for Propulson Laboratory) fast distribution of information of interest for as- tronomers 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 journals), Abstracts of recently accepted major re- Submitting your abstracts views (not standard conference contributions), Dis- sertation Abstracts (presenting abstracts of new Latex macros for submitting abstracts Ph.D dissertations), Meetings (announcing meet- and dissertation abstracts (by e-mail to ings broadly of interest to the star and planet for- [email protected]) are appended to mation and early solar system community), New each Call for Abstracts. You can also Jobs (advertising jobs specifically aimed towards submit via the Newsletter web inter- persons within the areas of the Newsletter), and face at http://www2.ifa.hawaii.edu/star- Short Announcements (where you can inform or re- formation/index.cfm 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 Galactic anticenter for my thesis. In order to get higher resolution I observed these clouds at the 5m millimeter- Leo Blitz wave telescope at McDonald observatory. Coming off the in conversation with Bo Reipurth telescope one time, I met Charlie Lada and Bruce Elmegreen who asked what I planned to do for a thesis. I told them that I wanted to investigate Blaauw’s ideas and that per- haps the HII regions drive shocks into the molecular clouds compressing the clouds and ultimately forming new stars. However, Charlie and Bruce were already working on their seminal paper on the mechanism for sequential star forma- tion and my vague thoughts on the matter nevertheless provided an impetus for them to finish quickly. Later that year, Charlie called to tell me that there was go- ing to be a meeting on Giant Molecular Clouds in Wales that summer (1977), the first meeting on that subject, and that I should go. I rounded up some financial sup- port for the trip and at the meeting wound up giving the review talk that Thaddeus was supposed to give. Gath- ering together the work of Pat’s group, I recognized that the GMCs we were mapping all had similar properties and Q: You have spent a lifetime studying molecular clouds, in although I didn’t realize it at the time, I presented what our Galaxy and in nearby galaxies. How did this interest turned out to be the first survey of GMCs anywhere. Since originate? it was the second talk of the meeting, every subsequent paper referred to it and the attention was a dizzying ex- A: It started in graduate school in 1976. Pat Thaddeus, perience for a fresh-faced graduate student. As a result, I my advisor, had just built a 1.2 m millimeter-wave tele- was hooked. scope on the roof of the physics building at Columbia, and Q each of his graduate students was given a six hour LST : In 1980 you and Frank Shu published an influential range to map the CO emission from a particular region of paper showing that giant molecular clouds generally have the sky. I chose the slot that included Orion, even though ages of less than 30 million years. What was the context the Orion GMCs had already been mapped. I turned my of this result? attention to the Rosette Nebula, which had been looked at A: At the end of the 1970s, a few people were speculating by one of the other students who found nothing but a few about the ages of GMCs. There was the camp that argued weak lines toward the center of the HII region. I was con- that GMCs were old (τ > 3 × 108y) led by Phil Solomon. vinced that the nebula had to have come from something Another group led by Frank Bash posited that GMCs were more substantial, so I started a systematic search by doing young with ages < 3×107 y old. At stake, among other a 10x10 map, and for a day nothing turned up. By the things, was an understanding of how the clouds form and time I got to point number 98 of the map, I started to get get destroyed. At the star formation discussion group I a strong signal, and by the time I got to point number 100, started at Berkeley, Frank Shu argued convincingly that the signal was booming! It became clear that there was in GMCs were young and I encouraged Frank to publish a fact a big GMC associated with the Rosette Nebula that paper on the subject. Frank agreed if I would be a co- was similar in size to the Orion GMC, but lies off to one author. One of the main issues was the fraction of the side of the nebula; the HII region and the molecular cloud total gas at various radii in the Galaxy, with the long complex are transverse to the line of sight. Nevertheless, lifetime advocates requiring that the molecular fraction the HII region could be seen to be clearly interacting with dominates and the short lifetime advocates arguing the the molecular cloud. I spent the next six days mapping opposite, since one of the key arguments had to do with out the GMC. Knowing its distance from the photometry mass flow between the two phases. Frank and I argued for of the O stars, I could get an estimate for the size and the latter and we provided a number of other quantitative mass of the cloud. To this day, I always sneak in a slide analytical arguments in the paper on GMC lifetimes. This of the Rosette nebula when I give a talk on GMCs. became a hotly contested topic. Both sides agreed that an Strongly influenced by Adriaan Blaauw’s 1964 Annual Re- acid test would be to see if GMCs were confined to spiral view article on sequential star formation in OB associa- arms in grand design spirals, but it took some years before tions, I started a program mapping the molecular clouds millimeter-wave interferometers were good enough to map connected to the OB associations in the direction of the GMCs in other galaxies and provide answers. Ultimately, 3 it became clear that for most of the disk, the atomic gas in overpressured regions perhaps in weak shocks. They are dominated and that GMCs are indeed concentrated in spi- largely free of star formation and there is no ”dark mat- ral arms. ter” such as anomalous dust to provide the gravitational Q: In 1982 you and Michel Fich and Tony Stark published binding. One could use the clouds to provide additional a very high-impact paper on CO radial velocities toward evidence that the Sun lies about 20 pc above the midplane HII regions. What was the origin of this project? of the Milky Way. A: Just before I started my postdoc, I was trying to figure Q: You have made a number of studies of the rotation out what I was going to do at Berkeley. A group of Cana- curve of the outer Milky Way, notably with your former dians led by Tony Moffat had just published the distances student Jan Brand. to many distant O stars in the outer region of the Milky A: I met Jan when I was on a visit to Leiden in the sum- Way. I knew from my thesis that O stars were almost mer of 1982. His original thesis plans had fallen through always associated with molecular clouds whose radial ve- and he was casting around for something else to do. His locities could be measured with high accuracy. With the original plan was to mount a 1mm receiver on an opti- distances from the Canadians and the velocities from the cal telescope and do molecular line observations using it. molecular clouds, I realized one could measure the rotation The problem was that there were so many reflections that curve of the outer Galaxy. The rotation curve was a hot it was impossible to get decent spectra and calibrate the topic in those years because Vera Rubin and others showed lines. But to measure the Galactic rotation curve, one that spiral galaxies tended to have flat rotation curves, im- needed only accurate velocities not intensities. So I sug- plying that there was a lot of dark matter around.