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THE FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 257 — 10 May 2014 Editor: Bo Reipurth ([email protected]) List of Contents

The Newsletter Interview ...... 3 My Favorite Object ...... 5 Editor: Bo Reipurth [email protected] Perspective ...... 10

Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers ...... 14 [email protected] Abstracts of Newly Accepted Major Reviews . 42 Technical Assistant: Hsi-Wei Yen New Jobs ...... 44 [email protected] New and Upcoming Meetings ...... 45

Editorial Board New Books ...... 47 Passings ...... 48 Joao Alves Alan Boss Short Announcements ...... 49 Jerome Bouvier Lee Hartmann Paul Ho Jes Jorgensen Cover Picture Charles J. Lada Thijs Kouwenhoven This image shows the LBN 777 in Tau- Michael R. Meyer rus close to the . The cloud was origi- Ralph Pudritz nally catalogued as Barnard 207, and has later be- Luis Felipe Rodr´ıguez come known as L1489. It contains the IRAS 04016+2610, a small multiple that Hans Zinnecker produces a molecular outflow and a chain of HH objects 360, 361, 362. The cometary shape of the The Star Formation Newsletter is a vehicle for globule suggests that the star formation event may fast distribution of information of interest for as- have been triggered by an external event. tronomers working on star and formation and molecular clouds. You can submit material Image courtesy Mark Hanson for the following sections: Abstracts of recently http://www.btlguce.com accepted papers (only for papers sent to refereed journals), Abstracts of recently accepted major re- views (not standard conference contributions), Dis- sertation Abstracts (presenting abstracts of new Ph.D dissertations), Meetings (announcing meet- ings broadly of interest to the star and planet for- Submitting your abstracts mation and early community), New Jobs (advertising jobs specifically aimed towards Latex macros for submitting abstracts persons within the areas of the Newsletter), and and dissertation abstracts (by e-mail to Short Announcements (where you can inform or re- [email protected]) are appended to quest information from the community). Addition- each Call for Abstracts. You can also ally, the Newsletter brings short overview articles submit via the Newsletter web inter- on objects of special interest, physical processes or face at http://www2.ifa.hawaii.edu/star- theoretical results, the early solar system, as well formation/index.cfm as occasional interviews. Newsletter Archive www.ifa.hawaii.edu/users/reipurth/newsletter.htm

2 in the control room, where people jumped and shouted when they viewed the screen with spectra never seen be- G¨osta Gahm fore. So did I when I saw the spectrum of RU Lupi. in conversation with Bo Reipurth We thought the strong emission lines from hot regions im- plied TTS enhanced by factors 105 com- pared to the . The concept of magnetospheric from circumstellar disks had not yet emerged. Fascinat- ing how our view of the phenomenon has changed since then. And can RU Lupi still hide some secrets? Over the last , my main partners on TTS have been Peter Petrov, Eric Stempels, Fred Walter, and Gregory Herczeg, and in our last paper (2013) we found evidence that the ac- cretion streams are curved and trailing the star. If con- firmed, I think an exciting step will be to match observed spectral variations with line transfer calculations based on recent models involving complex, non-axisymmetric mag- netic field configurations.

Q: In 1970, you were the first astronomer in Scandinavia Q: You did one of the pioneering studies of T Tauri to study young stars. From where came the inspiration? in X-rays using Einstein. Do your early conclusions still stand in light of what we have learnt from later missions? A: It all started after my supervisor Per Olof Lindblad arranged a stay with at the Lick Obser- A: After the first FUV surveys the next natural step was vatory. George gave me a coud´espectrum of RW Aur A to explore how TTS appear at higher energies. Timely, the and suggested I should think of something one could learn X-ray satellite Einstein was launched. There were predic- from it. I started to read all I could find about T Tauri tions around on high X-ray fluxes based on extrapolations stars (TTS) in the library. After a month we met again. of the strong ”hot” lines found in the FUV. I selected a I had many questions but he insisted on asking me what number of such stars and got so astonished when I found I thought. He was a wonderful mentor. that none was detected in X-rays. By chance, one field in- cluded a weak-line TTS, and yes, this object had a strong When back in Stockholm after a and half at Lick I signal. When closing a paper on this (1980) I realized that was hooked on young stars, and people said I was talk- at these relatively low X-ray energies the bulk of the X-ray ing only about TTS during breakfast, lunch and dinner. emission can be absorbed in the gas surrounding the stars. Despite this some students thought the subject was excit- I added a note on this at the last moment. ing. A group expanded including G¨oran Olofsson, Lennart Nordh, Ren´eLiseau, Peter Lindroos, Malcolm Fridlund, Since then X-ray observations have provided a wealth of and Erik Gullbring, some of whom are still active in as- data with information on stellar coronae, accretion shocks, tronomy. stellar flares and also shock-excited regions further out from the star, like Herbig-Haro objects. I did not continue Q: You have been studying RU Lupi for many years, in- myself within this field, except that we have collected X- cluding the first far-ultraviolet study. Does RU Lupi still ray data during periods of groundbased monitoring. It was surprise? always hard to arrange strictly simultaneous X-ray and A: After Lick we started simultaneous spectroscopic and optical observations, but now we have seen such studies photometric observations at ESO, which was still in its appearing in the literature. pioneering phase. Our first target was RU Lupi, a TTS Q: You and your collaborators have found evidence that with an extremely rich emission line spectrum. I have RW Aur A may be a spectroscopic binary. Has this been returned many times to this star as well as to RW Aur further supported by additional data? A. Not unusual that astronomers return to the place of the crime, I have found. Each time we gained some new A: There was indeed a time when I thought the small- insights, but new questions always popped up. amplitude periodic velocity changes we detected in TTS could flag the presence of brown dwarfs in close , and At the time new spectral windows became accessible for which would eventually be swallowed by the star. It could studies of TTS. Observers from all parts of Europe gath- also explain how non-axisymmetric accretion streams de- ered in Villafranca, Spain to conduct FUV observations velop in their combined magnetospheres. I was arguing with the IUE satellite. I remember many exiting moments with Petrov, who thought we instead were dealing with

3 two accretion areas not aligned with the stellar magnetic forces, which was partly true. Per Carlqvist ar- axis. Colleagues called our conversations quarrels, and I gued that plasma physics should be applied in full scale remember how we spent a whole evening in the dancing in models of interstellar clouds. Even the cold molecu- hall on a ferry between Stockholm and Helsinki totally oc- lar clouds are by standard definitions plasmas. We stud- cupied by finding the weak points in each story and ways ied twisted, filamentary clouds in CO with collegues in to defend our own conclusions. In fact, quarrels can be Finland and Onsala, Anlaug Kaas and P¨aivi Harjunp¨a¨a very refreshing and creative. We finally presented both mapped polarization, and with Helmuth Kristen we sur- views in a paper on RW Aur A (2001). veyed elephant trunks in 10 H II regions in Hα at the Later, when investigating the same phenomenon in RU Nordic Optical Telescope. Lupi, I had to admit that Peter probably was on the right We found that many trunks are composed of thin molecu- track after all. The periodic velocity changes are related to lar threads that can be confined over . Several look cold and hot spots on the rotating star. Usually we agree like twisted coaxial cables and shaped like double helices in on how to interpret observations, and our collaboration some cases. Not far-fetched to think that electromagnetic has always survived since we met in Moscow back in 1974. forces play an important role in sculpting these features. As the Swedish poet Nils Ferlin wrote: God may forgive Carlqvist developed the ”Theory of twisted trunks”. me certain lines. However, one must check each star care- Magnetic fields and electric currents are here to stay, and fully. Recently, K´osp´al et al. found that in EX Lup such over the last decade some very impressive models have velocity variations are caused by a close component. been published treating the evolution of ”magnetic” shells Q: You had the interesting idea to look for young binaries and trunks in H II regions. pairing OB stars with T Tauri stars, and found a number Q: Your latest interest are the small ”globulettes” in HII of such cases, work later continued by Peter Lindroos. Do regions. What have you learnt? these companions appear to be normal T Tauri stars? A: I always loved to be in a control room and see data ac- A: When Lindroos entered our group I had in my drawer cumulating on-line. At NOT the trunks were seen as dark a compilation of early-type stars with faint visual compo- silhouettes against the nebular background on the screen. nent(s). A few of these secondaries were known to be of I then noticed some tiny dark spots, which I thought were late type. The idea was to collect Str¨omgren photometry bad pixels in the camera. I moved the telescope a bit, and and spectra for both primaries and secondaries. From the the spots followed the shift, they were real. photometry one would get the age of the . If the Now and then I wondered about their . I found systems were physical, also the secondaries must be very that several people had already paid attention to similar young. Then their positions in the HR diagram could be cloudlets, for instance you Bo! Then Tiia Grenman in compared to model tracks, and one could check for spectral Lule˚awas looking for a thesis project, and we made an characteristics of youth, like lithium and emission lines. inventory of tiny clouds from the NOT images in several Lindroos turned on and did a very thorough survey of H II regions. We called them globulettes since they are of such systems as his thesis work. He concluded that most a different nature than globules and , and we just systems are physical. Many secondaries populate a region published a survey of such objects in the Nebula. above the main-sequence, and their strong Li line indicate We have now measured sizes and for more than 400 youth. Several stars show weak Hα emission. He had globulettes. Most are of planetary and they have all located a population of post-T Tauri stars. been accelerated outwards from the central cluster. Lindroos left after his graduation. I meet him I have been so happy to see an entirely new now and then, and he was of course very pleased to know of collaborators blossom, including Carina Persson at On- that the objects later were named the Lindroos stars. sala and Lauri Haikala and Minja M¨akel¨ain Helsinki. We Q: You and your collaborators have been studying rotating have now added radio and NIR observations. A question is and twisted elephant trunks in HII regions. Is this likely whether globulettes may collapse to form planetary mass to be a general phenomenon? objects, which will shoot into surrounding space like bul- lets. There is an enormous reservoir of free floating A: In the eighties I spent some time at the Alfv´en labo- in the . Did some form in globulettes? Well, this is ratory doing laboratory experiments shooting hot plasma a very speculative idea, but we have discovered dense cores into different configurations of magnetic fields and elec- in many of these objects, so I think it is not impossible. tric currents. The idea was to learn something about the excitation of Herbig-Haro objects. That was fun, but A team at UCL London has started modelling our objects. more important, I got in touch with the plasma physi- By the end of May observers and theoreticians will meet cists. They thought astronomers were neglecting electro- in Greece to discuss topics like this. Astronomy is fun!

4 My Favorite Object The Double Cluster h & χ Persei Estelle Moraux

Figure 1: The Double Cluster h & χ Persei (or NGC 869 and NGC 884, respectively on the right and left). Both clusters have an apparent dimension of 30 arcmin. Copy- right Robert Gendler 2006. 1 Introduction & motivation

The double cluster (02h20m, +57d08’) is the com- star 20 arcmin west of it. Sir William Her- mon name for the two open clusters h & χ Persei (also schel, working on the completeness of his Double Stars known as NGC 869 and NGC 884, respectively) in the Catalogue, was the first astronomer to recognize h & χ Perseus constellation. This pair is exceptional due to the Persei as stellar clusters in 1780 thanks to the use of the large number of young bright O and B stars in each cluster, telescope. These are his notes when referring to χ Per- and their closeness whilst still being clearly distinguished. sei: “Multiple. An astonishing number of small stars all The clusters visual magnitudes (respectively 4.9 and 5.7, within the space of a few minutes. I counted not less than Slesnick et al. 2002) make them visible to the naked eye 40 within my small field of view.”1 and a favorite of amateur astronomers. In small telescopes the double cluster appears as a beautiful assemblage of bright stars located in a rich star field. Dominated by bright blue stars, the clusters also host a few orange stars that add to the visual interest (see Fig. 1). The double cluster was first catalogued by Hipparchus (130 BC) but was probably known since antiquity. It is not clear, though, when astronomers became aware of its dou- ble nature. Claudius Ptolemy described them as a “dense mass”, and Copernicus as a “nebulous star”. Tycho Brahe catalogued this object as a single star and described it as “enveloped”, “wrapped” or “enshrouded” in nebulosity. Analysing Johann Bayer’s star , Uranometria 1603, partly reproduced in Fig. 2, we can realize the existence of an h and a χ label in the sword hand of Perseus and it Figure 2: Perseus represented in Johann Bayer’s star atlas, is thought that the double cluster represents the jeweled Uranometria 1603. Note the h and χ in the sword hand handle of Perseus’s sword. It is not clear however if the of Perseus. This image was retrieved from the Linda Hall h and χ in this atlas represent the same astronomical ob- Library online, http://lhldigital.lindahall.org/. jects that are today associated with the double cluster as they are reversed to the current notation and represented 1 with wrong magnitudes. According to O’Meara & Green Citation taken from the William Herschels Cat- alog, maintained by Bruce MacEvoy, that can be found at (2003), it seems that χ Persei historically corresponded http://www.handprint.com/ASTRO/herschel.html. to the double cluster, and very likely h Persei was a 6th

5 h& χ Persei is the largest double cluster known nowadays larger or equal to ten at each telescope. in the . Being very dense, with a high density We then produced the light curves for each object detected of evolved high mass stars (O-B giants/ supergiants and in the images of each telescope following the procedure dwarfs) it was intensively studied in the last 200 years, described in Irwin et al. (2007a). For the CFHT dataset, leading to a gradual improvement in the knowledge of its the achieved photometric precision for each data point is properties. Since early 1900, it has been the target of ′ better than 2 mmag for the brightest objects (iCFHT ≤ extensive photometric surveys using photographic plates ′ 16), with a scatter < 1 per cent up to iCFHT ≃ 19.5. The (e.g., van Maanen 1911; Oosterhoff 1937) and spectro- photometric precision for the Maidanak data is also very scopic studies (e.g., Trumpler 1926; Bidelman 1943; Schild good, while for the CrAO and Byurakan photometry, the 1965), leading to some controversy about the distances and limit for the rms scatter is around 5 mmag. relative ages of h and χ Per. More recent studies (e.g., Keller et al. 2001; Capilla & Fabregat 2002; Slesnick et al. To take the best benefit of our sampling, we performed 2002; Uribe et al. 2002; Bragg & Kenyon 2005; Mayne et the period search on objects detected in both CFHT and al. 2007; Currie et al. 2010) are now converging to similar Maidanak images, which allowed us to be sensitive to pe- properties for both clusters, with a distance modulus of riodic variations on timescales of less than 0.2 day and up ∼11.8 (d ∼2.3 kpc), an E(B − V ) ∼ 0.54 and to 20 days. Photometry obtained at CrAO and Byurakan an age of ∼13 Myr (Mayne & Naylor 2008). h Per is about was only used a posteriori to check the goodness of the 30% more populous than χ Per with at least ∼3000 stars period found. Selection of candidate members using em- within its 10 arcmin center and has an estimated mass of pirical isochrones in various CMDs in the optical and the ∼ 4700 M⊙ (Currie et al. 2010). near- (see Fig. 3) identified 2287 objects that were detected in both CFHT and Maidanak data. We restricted The age of the double cluster probes a very interesting our period analysis to these sources. phase for pre- evolution, and in particu- lar for stellar evolution. By the age of the clusters (∼ 13 Myr), the has fully disappeared and the stars can freely spin-up while evolv- ing towards the zero-age main sequence (ZAMS). Hence, deriving the rotational distribution of hundreds of coeval low-mass stars in this cluster allows to characterize the an- gular momentum properties of stars at the end of the ac- cretion phase, when they have finally acquired their total mass. This was the main aim of our recent study (Moraux et al. 2013), as well as to investigate the angular momen- tum evolution of low mass stars using the distribution of rotation rates at ∼13 Myr as initial conditions for further evolution to the ZAMS and onto the main sequence (MS).

2 h Persei rotational period distri-

bution ′ ′ Figure 3: iCFHT , V − iCFHT color magnitude diagram. Left: All the objects located between the two solid lines Within the framework of the Monitor project (Aigrain et have been selected as possible cluster members. Right: al. 2007), we conducted a multisite photometric moni- The red open circles show the objects that have been an- toring of h Persei during the fall 2008 using four differ- alyzed, while the green crosses show the periodic objects. ent telescopes: the 3.6m Canada-France-Hawaii Telescope (CFHT), the 1.5m telescope in Maidanak (Uzbekistan), the 2.6m Shajn telescope (ZTSh) at the Crimean Astro- The light curves of the candidate cluster members were physical Observatory (CrAO, Ukraine), and the 2.6m tele- searched for periodic modulations due to scope of Byurakan Observatory (Armenia). The total using three different methods : Lomb-Scargle periodogram amount of time spent monitoring the cluster was ∼ 110 (Scargle 1982; Horne & Baliunas 1986), CLEAN discrete hrs, spread over two months from September 5 to Octo- Fourier transform (CLN DFT, Roberts et al. 1987) and ber 27, 2008. The observations were done in the I-band, string-length minimization (Dworetsky 1983). After re- and the individual exposure times were adapted to reach moval of spurious periods resulting from the nightly sam- ′ − the equivalent of iCFHT ≃ 21, with a signal-to-noise ratio pling rate (frequencies around 0.5 and 1d 1), and eye

6 Figure 4: Phased light curves of periodic h Per candidate members (red dots: CFHT, black dots: Maidanak). The object number is given in each panel (top) as well as the period (in days, bottom left) and amplitude (in magnitude, bottom right). The light curves are ordered by decreasing periodogram peak power. Only the first 21 light curves are shown here as an example. examination of the phase folded light curves with a low 3 Angular momentum evolution false alarm probability (FAP ≤ 0.05), we found 586 peri- odic objects in the mass range 0.4 ≤ M/M⊙ ≤ 1.4. The The derivation of hundreds of rotational periods for low- phased light curves of 21 periodic variables are shown in mass stars in the 13 Myr-old h Per cluster provides a new Fig. 4 as an example. In some cases, especially for ob- time step to investigate pre-main sequence angular mo- jects with short periods, the phased light curve provides mentum evolution. This time step, which was not previ- clear evidence for phase and/or amplitude variations over ously covered by other cluster studies (e.g., Irwin & Bou- the time span of the observations, indicative of spot evo- vier 2009; Messina et al. 2010, 2011), is particularly in- lution and/or surface differential rotation over a timescale teresting as it marks the end of the PMS disk accretion of weeks. process. Disk accretion is thought to be largely terminated As synchronized binaries are expected to have a different by 10 Myr (Kennedy & Kenyon 2009; Fedele et al. 2010), angular momentum evolution than detached systems and leaving at most a few percent of stars still actively accret- single stars, we removed them from our sample to further ing from their disks in h Per (Currie et al. 2007). The investigate stellar rotation at 13 Myr and angular momen- “disk-locking process” by which stars are prevented from tum evolution prior to the arrival on the main sequence. spinning up during their early PMS evolution is therefore The obtained period distribution of h Per candidate mem- over for most of the h Per low-mass population. These bers is shown as a function of mass in Fig. 5. It exhibits a stars are thus expected to freely spin up as they contract wide dispersion, with most of the measured periods in the towards the ZAMS, which they eventually reach at an age range ∼ 0.3 to ∼ 9 days and a few slow rotators around 15 of 22, 33, 66, and 100 Myr for a mass of 1.2, 1.0, 0.7, and days, and does not show any clear dependence on mass. 0.5 M⊙, respectively. The rotational distribution of h Per In particular, the upper and lower envelopes (correspond- members is thus particularly suited to investigate stellar ing respectively to slow and fast rotators) is remarkably spin-up at the end of PMS evolution and on the approach flat over the whole mass range. On a log scale, the period to the ZAMS. distribution appears somewhat bimodal, especially at low Figure 6 compares the rotational distribution of h Per masses, with a primary broad peak around 4-10 days and members with those of solar-type and lower mass mem- a secondary peak at a fraction of a day. There is also a bers of various open clusters over the age range from 5 to slight indication that the 0.4-0.6 M⊙ mass objects have a 150 Myr. At all ages, a significant spread is seen in the larger fraction of fast rotators, which is in agreement with rotational period distributions. the finding of previous studies (e.g., Herbst et al. 2001, The upper envelope of the period distribution, located at Irwin et al. 2007b, 2008a, 2008b). ∼10 day in h Per, does not appear to evolve much between 5 and 40 Myr overthe mass rangefrom 0.4 to 0.9 M⊙. This suggests that at least a fraction of slow rotators are pre-

7 Figure 5: Periods detected for 508 h Per photometric can- Figure 6: Period versus mass distributions for clusters didate members (excluding synchronized binaries with pe- with an age ranging from 4 to 150 Myr. The clusters’ riod ≤1d) are shown as a function of . Periods name and age are given in each panel. Red dotted lines are are plotted on a linear scale in the upper panel and on a drawn at periods of 0.2 and 10 days to guide the eye. Ref- log scale in the lower one. On the top panel, the upper erences: Cep OB3b: Littlefair et al. (2010); NGC 2362: ′ x-axis scale corresponds to iCFHT -band magnitude. Irwin et al. (2008a); NGC 2547: Irwin et al. (2008b); Pleiades: Hartman et al. (2010); M 50: Irwin et al. (2009); NGC 2516: Irwin et al. (2007b); M35: Meibom et al. (2009). vented from spinning up over this timescale. By the age of the Pleiades (125 Myr), the upper envelope of the dis- tribution has decreased towards faster rotation for masses larger than 0.7 M⊙. A significant fraction of lower mass lack of mass dependency in the rotational distribution of stars, even at this age, still exhibits long periods, sug- the former, while the latter exhibit a narrow rotation-mass gesting that the pre-ZAMS spin-up is more efficient for relationship for masses larger than about 0.7 M⊙. Indeed, solar-mass than for low-mass stars. the largest scatter of rotation rates over the investigated In contrast, the lower envelope of the period distribu- mass range is observed for the 13 Myr-old h Per cluster, tion exhibits quite a drastic evolution from 5 Myr to the which is at the end of the PMS accretion phase. This ZAMS. In h Per, the lower envelope appears rather flat result supports the role of disk accretion in establishing the initial dispersion of stellar angular momentum in low- over the mass range 0.4-1.1 M⊙ at a period of ∼0.2-0.3d. In younger clusters, the minimum period seems to strongly mass stars (Edwards et al. 1993; Bouvier et al. 1993; Rebull et al. 2004). depend on mass, ranging from ∼0.4-0.5d at 0.4-0.6 M⊙ to 1.0d or more for solar-type stars. This provides good evi- While the rotational distributions of fast and slow rotators dence for PMS spin-up for the fast rotators between 5 and provide some clues to the angular momentum evolution of 13 Myr. From 13 to 130 Myr, the fastest rotators in the PMS stars, the complete distributions have to be modeled 0.8-1.1 M⊙ mass range have been spun down, presumably to understand the processes at play. We thus computed upon their arrival on the ZAMS, while lower mass stars angular momentum evolution models starting from the ob- down to 0.4 M⊙ still exhibit the same maximum rotation served 5 Myr rotational distributions as initial conditions rate of ∼0.3d. and evolved them at ages of 13, 40, and 130 Myr to com- The most striking difference between the 13 Myr-old h Per pare with observations. The models assume all stars are cluster and ZAMS clusters at an age of 125-150 Myr is the released from their disk at 5 Myr and therefore do not in- clude any “disk-locking” process after this age. Angular

8 momentum loss due to stellar winds are included in the Irwin, J., Aigrain, S., Bouvier, J., et al. 2009, MNRAS, 392, 1456 way described in Irwin & Bouvier (2009). Core-envelope Keller, S. C., Grebel, E. K., Miller, G. J., & Yoss, K. M. 2001, AJ, decoupling is also included in the model through the in- 122, 248 troduction of a coupling timescale τc over which angular Kennedy, G. M., & Kenyon, S. J. 2009, ApJ, 695, 1210 momentum is exchanged between the radiative core and Littlefair, S. P., Naylor, T., Mayne, N. J., Saunders, E. S., & Jeffries, the convective envelope (Allain 1998). Our results sug- R. D. 2010, MNRAS, 403, 545 gest that core-envelope decoupling occurs on a timescale Mayne, N. J., Naylor, T., Littlefair, S. P., Saunders, E. S., & Jeffries, inversely proportional to surface rotation. Furthermore, R. D. 2007, MNRAS, 375, 1220 our models indicate that less than 10% of stars may re- Mayne, N. J., & Naylor, T. 2008, MNRAS, 386, 261 main coupled to their disk beyond 5 Myr in order to repro- Meibom, S., Mathieu, R. D., & Stassun, K. G. 2009, ApJ, 695, 679 duce the spin evolution to the ZAMS, in agreement with Messina, S., Desidera, S., Turatto, M., Lanzafame, A. C., & Guinan, current estimates of disk lifetimes. E. F. 2010, A&A, 520, A15 Messina, S., Desidera, S., Lanzafame, A. C., Turatto, M., & Guinan, E. F. 2011, A&A, 532, A10 4 Future work Moraux, E., Artemenko, S., Bouvier, J., et al. 2013, A&A, 560, A13 OMeara, S. J. & Green, D. W. E. 2003, Sky and Telescope, 105, 116 We are now investigating the rotational period distribu- Oosterhoff, P. T. 1937, Annalen van de Sterrewacht te Leiden, 17, tion of χ Per using similar data obtained in 2010 to look A1 for any possible difference between the two clusters. More- Rebull, L. M., Wolff, S. C., & Strom, S. E. 2004, AJ, 127, 1029 over, the CFHT light curves obtained in 2008 and 2010 for Roberts, D. H., Lehar, J., & Dreher, J. W. 1987, AJ, 93, 968 both clusters will be analysed to search for period evolu- Scargle, J. D. 1982, ApJ, 263, 835 tion over a two year baseline and investigate differential rotation. Schild, R. E. 1965, ApJ, 142, 979 Slesnick, C. L., Hillenbrand, L. A., & Massey, P. 2002, ApJ, 576, 880 Other clusters with an age between 10 Myr and the ZAMS are also being investigated to get further constraints on the Trumpler, R. J. 1926, PASP, 38, 350 early stellar angular momentum evolution. Uribe, A., Garc´ıa-Varela, J.-A., Sabogal-Mart´ınez, B.-E., Higuera G., M. A., & Brieva, E. 2002, PASP, 114, 233

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9 6 The Brief History of Young Spec- Perspective troscopic Binaries PMS Spectroscopic Binaries Although T Tauri stars have been studied since the 1940s (Joy 1945) and spectroscopic binaries for even longer (Pick- Lisa Prato ering 1890), remarkably it was not until Herbig (1977) that the overlap in these two populations was noted. In the following decade, Mathieu et al. (1989), motivated by the study of binary formation, began to search system- atically for the pre-main sequence (PMS) spectroscopic binary population in Taurus. In their landmark paper, Mathieu et al. determined that short-period (P<100 days) spectroscopic binaries are likely not the drivers of circum- stellar disk dissipation in weak-lined systems, presented orbital solutions for 5 new spectroscopic pairs, identified the transition to non-zero eccentricity binaries at peri- ods of >4 days, and used the mass limits imposed by the double-lined spectroscopic solution for NTTS 162814−2427 to test the PMS evolutionary calculations of VandenBerg (1985) and Cohen & Kuhi (1979). By the mid-1990s, Mathieu (1994) had compiled a census of 12 double-lined and 13 single-lined young spectroscopic binaries. 5 Motivation

As an undergraduate I believed that few things could be 7 Enter the Infrared more outdated and stultifying than the study of low-mass binaries; in my mind real astronomy dealt with big, ex- Figure 1 shows the most recent results for the mass ra- plosive things, AGN, supernovae. So why do I now spend tio distribution of double-lined PMS systems, which now a significant fraction of my time very happily on young, number over 50. The obvious bias toward a mass ratio of low-mass spectroscopic binaries, and why are they of core importance to the entire field of star formation? The pri- mary virtue of a stellar binary is its adherence to simple Keplerian motion; this makes it possible to dynamically determine orbital and stellar properties with relative pre- cision. The attractive hook in the study of young spectro- scopic binaries is that they provide an unambiguous route to the determination of mass ratios and in particular masses. These properties are fundamental to our understanding of binary formation, young star evolu- tion, and the relationship between planets and their host stars. The latter is underscored by the growing number of transiting planets found by the Kepler mission which spectroscopic binaries (e.g., Orosz et al. 2012). Although there is some ambiguity as to the exact fraction of binary systems, there is little doubt that the majority of stars reside in binary or multiple configurations. Therefore, bi- naries are integral to star formation while at the same time providing an invaluable tool for the measurement of fun- damental young star properties useful for anchoring the- ory to observation and thus for the characterization of the global young star population. Figure 1: Visible light and infrared measured mass ratios for double-lined T Tauri spectroscopic binaries.

10 unity among the visible-light-identified pairs reflects the fact that flux scales as a steeper function of mass in the visible than in the infrared. In the mid-1990s, Mike Simon and I began to leverage this infrared advantage on the single-lined systems listed in Mathieu (1994); for about 90% of these binaries, colleagues, students, and I have determined double-lined orbits (e.g., Steffen et al. 2001; Prato et al. 2002a,b; Simon & Prato 2004; Schaefer et al. 2008; Mace et al. 2012; Simon et al. 2013; Torres et al. 2013; Karnath et al. 2013). Other sources of single- lined systems include Alcal´aet al. (1996, 2000), Webb et al. (1999), and Prato (2007) from which we selected additional targets (Mace et al. 2009; Rosero et al. 2011; Ru´ız-Rodr´ıguez et al. 2013). Thanks to the heightened sensitivity to the secondary star spectrum achievable in the infrared, and the power of two- dimensional cross-correlation (Zucker & Mazeh 1994), it has been possible to measure mass ratios in young sys- Figure 2: Examples of scatter between 1−100 Myr age tems down to q = M2/M1 = 0.2. Furthermore, in col- PMS mass tracks for 1.0, 0.6, and 0.1 M⊙ (Simon 2008). laboration with Guillermo Torres, it has become evident For the Baraffe et al. (1998, BCAH) 0.1 M⊙ track a mixing that, once both the primary and secondary spectral types length, α, of 1.0 was used; otherwise α =1.9. SDF=Siess and, perhaps more significantly, v sin i, have been esti- et al. (2000), PS=Palla & Stahler (1999), DM=D’Antona mated on the basis of the infrared spectra, it is possible & Mazzitelli (1994), Yi=Yi et al. (2003). to then extract full double-lined solutions on the basis of the visible light data as well (Mace et al. 2012; Torres et al. 2013; Kellogg et al. 2014 in prep). In this way by the requirement for an independent distance estimate, we have been able to exploit archival visible light data or (2) by measuring the radial velocities (RVs) of both for more precise double-lined solutions. Our observed in- stars in a spectroscopic binary to obtain the orbital pe- frared (H-band) spectral library is publicly available at riod, eccentricity, time of periastron passage, longitude of www2.lowell.edu/users/lprato/hband/homepage.html. periastron, and component velocity semi-amplitudes (P, T, e, ω, K1, and K2) combined with the inclination, i, measurable in an angularly resolved (e.g., 8 Young Star Masses Schaefer et al. 2008) or in an eclipsing system (e.g., Stas- sun et al. 2004): PMS stellar masses have traditionally been estimated by determining and effective temperature, map- −7 2 2 3/2 ping these quantities onto the Hertzsprung-Russell (H-R) 1.036 × 10 (K1 + K2) K2P (1 − e ) M1 = M⊙ (1) diagram, and comparing the results with models of star sin3i formation and evolution (e.g., Weinberger et al. 2013). −7 2 2 3/2 However, models for low-mass stars suffer from the lack of 1.036 × 10 (K1 + K2) K1P (1 − e ) M2 = 3 M⊙ (2) a reliable observational framework and incomplete knowl- sin i edge of molecular opacities and diverge on the basis of −1 where K1 and K2 are in km s and P is in days. choices for the equation of state and somewhat arbitrary initial conditions (Baraffe et al. 2003). Figure 2 illustrates The observational challenge is to identify young binaries the discrepancies between five sets of tracks for low-mass with sufficiently short periods that we can determine their stars. Ideally, a set of well-characterized young stars with double-lined spectroscopic solution while at the same time masses measured to a precision of a few % or better, span- angularly resolving the components via adaptive optics ning the full range from ∼0.1 to ∼1.0 M⊙, and consistent imaging, non-redundant masking, and interferometry, or effective temperatures and , are needed. to identify young binaries in eclipsing systems. To date, there are only about a dozen pairs with components of < There are two ways to dynamically measure young star 1 M⊙ and sufficiently precise (better than 10%), dynami- masses: (1) by mapping the Keplerian rotation of a cir- cally determined absolute masses adequate for the calibra- cumstellar or circumbinary disk interferometrically (e.g., tion of the low-mass theoretical models (e.g., Hillenbrand Guilloteau et al. 2013), although this approach is limited & White 2004; G. Schaefer, priv. comm.). The good news

11 is that some of our recent observational results (e.g., Tor- shown in Figure 3 (mass ratio is 0.98 and res et al. 2013; Schaefer et al. 2012; Simon et al. 2013; velocity, γ, is −6.78 km s−1; Rosero et al. 2011) were Le Bouquin et al. 2013) have provided a few more precise combined in all 286 possible combinations of three and anchor points and are spurring theorists to revisit these the mass ratio calculated using the negative of the slope stellar models (I. Baraffe, priv. comm.). We are inching of the primary versus secondary RV (Wilson 1941) for each our way toward a substantial sample of precise, absolute, set of 3 radial velocities. A Gaussian fit to the resulting young star masses. histogram showed that mass ratio determinations based There are, of course, undiscussed challenges in placing on three observations are strongly peaked spectroscopic binary components, even those with pre- at 0.98 with a FWHM spread of only 0.08 in mass ratio, il- cisely measured masses, on an H-R diagram (!). One of lustrating the reliability of the approach (V. Rosero, priv. comm.). the foremost is the determination of Teff , and another the determination of luminosity, or , which require a relatively precise knowledge of the dis- tance to the system. M. Simon and others are attacking the issue of Teff and the exquisite work of R. Torres, L. Loinard, and colleagues (e.g., Torres et al. 2009), not to mention the results at the end of its 5-year mission in 2018, address the distances to young stars in nearby regions. Also, for an angularly resolved visual binary that is also a double-lined spectroscopic binary, distance may be directly determined (Schaefer et al. 2008).

9 Mass Ratio and Other Distribu- tions

Dynamically measured mass ratios number <5 dozen (Fig- ure 1). Most stars in the Solar neighborhood reside in binary or multiple systems, yet we do not yet have a sat- isfactory picture of how they form, especially the shortest period, i.e. spectroscopic binary, systems. Theory has Figure 3: Linear fit to the primary vs. secondary radial reached a point where simulations of the formation of en- velocities for RX J1622.7-2325Nw (Rosero et al. 2011). tire clusters of young stars yield mass ratio distributions Uncertainties in the RV are not shown because they are −1 for sub-samples of various primary star masses (e.g., Bate smaller than the symbol size (1−2 km s ). 2012). Unhappily, there are no analogous observed young star mass ratio distributions for comparison. Clearly far With the acquisition of a large sample of double-lined spec- larger observed samples are needed to guide further theo- troscopic binaries (preferably hundreds!), complete within retical developments. individual star forming regions, broad areas of heretofore unexamined study will open up. Spectroscopic binary Identifying spectroscopic binaries is a time-consuming pro- properties will facilitate a new perspective on star forma- cess requiring at least two and preferably at least three tion. epochs of observations (e.g., Prato 2007; F¨ur´esz et al. 2008; Tobin et al. 2009). Orbital solutions with better These properties include: than 10% uncertainties in the elements require a dozen, • The total frequency of spectroscopic binaries in a given or better a couple of dozen, observations distributed in region phase. The beauty of a mass ratio measurement is that, • The frequency of spectroscopic binaries as a function of unlike the other orbital properties, it is possible to obtain primary star mass (or spectral type) with as few as three observations following Wilson (1941), • The mass ratio distribution of spectroscopic binaries illustrated in Figure 3. To test how robust a mass ratio • The period distribution of spectroscopic binaries measurement is on the basis of three pairs of radial ve- • The eccentricity distribution of spectroscopic binaries locities, we conducted an experiment using a system for Some questions that will be possible to explore: which numerous radial velocity pairs were available. The • How do short-period spectroscopic binaries form? Do thirteen pairs of primary and secondary radial velocities they dynamically evolve and if so how quickly? for the young spectroscopic binary RX J1622.7-2325Nw • How do circumstellar and circumbinary disks form and

12 evolve in such systems? (There is ample evidence for careful analysis the results of the complete GAIA mission both!) will reveal the orbital inclinations. In combination with • Do global parameters such as the mass ratio distribution Equations (1) and (2) this will yield masses for systems vary between star forming regions? with periods down to a few days at distances of out to ∼1 • What do the spectroscopic binary population properties kpc. It’s an excellent time to be in the young spectroscopic tell us about a star forming region? About angular mo- binary business! mentum in star forming regions? • What are the relationships between mass, Teff , and lu- minosity for T Tauri stars of a given age? 11 Acknowledgements • What is the eccentricity vs. log period distribution for coeval populations of spectroscopic binaries? Can this be This manuscript benefitted from comments on the part used effectively as a stellar chronometer? of my colleagues most involved in this work with me, Gail Schaefer, Guillermo Torres, and Michal Simon. For- mer students Gregory Mace, Viviana Rosero, Dary Ru´ız- 10 How Do We Get There Rodr´ıguez, and Nicole Karnath, and colleague Lawrence Wasserman have all contributed significantly to the efforts Complete surveys for spectroscopic binaries in the nearby described here. star forming regions are necessary but have never been References: carried out given the intensive observing required. An ex- Alcal´a, J. M., et al. 2000, A&A, 353, 186 cellent approach taken by F¨ur´esz et al. (2008) and Tobin Alcal´a, J. M., et al. 1996, A&AS, 119, 7 et al. (2009) leveraged the multiplexing advantage of the Baraffe, I., et al. 1998, A&A, 337, 403 Hectochelle instrument at the MMT. With over 200 fibers Baraffe, I., et al. 2003, A&A, 402, 701 Bate, M. R. 2012, MNRAS, 419, 3115 distributable over a degree of sky at once, Hectochelle Cohen, M., & Kuhi, L. V. 1979, ApJS, 41, 743 (Szentgyorgyi et al. 2011) is ideal for the observation of D’Antona, F., & Mazzitelli, I. 1994, ApJS, 90, 467 many stars simultaneously in dense star forming regions F¨ur´esz, G., et al. 2008, ApJ, 676, 1109 such as and NGC 2264. With adequate integration Guilloteau, S., et al. 2013, A&A, 549, 92 Herbig, G. H. 1977, ApJ, 214, 747 time and hence sufficiently high signal to noise ratios, com- Hillenbrand, L. A., & White, R. J. 2004, ApJ, 604, 741 plete surveys are within reach over the next few years with Joy, A. H. 1945, ApJ, 102, 168 such a facility. Furthermore, many, if not most, stars in Karnath, N., et al. 2013, AJ, 146, 149 smaller regions, such as Taurus and , have been Le Bouquin, J.-B., et al. A&A, 561, 101 Mace, G. N., et al. 2009, AJ, 137, 3487 observed at high spectral resolution repeatedly and their Mace, G. 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13 Abstracts of recently accepted papers

Large-scale magnetic fields in Bok globules Gesa Bertrang1, Sebastian Wolf1 and Himadri S. Das2 1 University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstr. 15, 24118 Kiel, Germany 2 Assam University, Department of Physics, Silchar – 788 011, India E-mail contact: gbertrang at astrophysik.uni-kiel.de Context: The role of magnetic fields in the star formation process is a contentious matter of debate. In particular, no clear observational proof exists of a general influence by magnetic fields during the initial collapse of molecular clouds. Aims: Our aim is to examine magnetic fields and their influence on a wide range of spatial scales in low-mass star- forming regions. Method: We trace the large-scale magnetic field structure on scales of 103 − 105 AU in the local environment of Bok globules through optical and near-infrared and combine these measurements with existing submillimeter measurements, thereby characterizing the small-scale magnetic field structure on scales of 102 − 103 AU. Results: For the first time, we present polarimetric observations in the optical and near-infrared of the three Bok globules B335, CB68, and CB54, combined with archival observations in the submillimeter and the optical. We find a significant polarization signal (P > 2 %, P/σP > 3) in the optical and near-infrared for all three globules. Additionally, we detect a connection between the structure on scales of 102 − 103 AU to 103 − 104 AU for both B335 and CB68. Furthermore, for CB54, we trace ordered polarization vectors on scales of ∼ 105 AU. We determine a magnetic field orientation that is aligned with the CO outflow in the case of CB54, but nearly perpendicular to the CO outflow for CB68. For B335 we find a change in the magnetic field oriented toward the outflow direction, from the inner core to the outer regions. Conclusion: We find strongly aligned polarization vectors that indicate dominant magnetic fields on a wide range of spatial scales. Accepted by A&A http://www.aanda.org/articles/aa/pdf/forth/aa23091-13.pdf

Planetesimal driven migration as an explanation for observations of high levels of warm, Amy Bonsor1,2, Sean N. Raymond3,4, Jean-Charles Augereau1, and Chris W. Ormel5 1 UJF-Grenoble 1 / CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Greno- ble, F-38041, France 2 School of Physics, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK 3 CNRS, UMR 5804, Laboratoire d’Astrophysique de Bordeaux, 2 rue de l’Observatoire, BP 89, F-33271 Floirac Cedex, France 4 Universit´ede Bordeaux, Observatoire Aquitain des Sciences de l’Univers, 2 rue de l’Observatoire, BP 89, F-33271 Floirac Cedex, France 5 Astronomy Department, University of California, Berkeley, CA 94720, USA E-mail contact: amy.bonsor at gmail.com High levels of exozodiacal dust have been observed in the inner regions of a large fraction of main sequence stars. Given the short lifetime of the observed small dust grains, these ‘exozodis’ are difficult to explain, especially for old (>100 Myr) stars. The exozodiacal dust may be observed as excess emission in the mid-infrared, or using interferometry. We hypothesise that exozodi are sustained by scattered by planets inwards from an outer belt, where collision timescales are long. In this work, we use N-body simulations to show that the outwards migration of a planet into a belt, driven by the scattering of planetesimals, can increase, or sustain, the rate at which planetesimals

14 are scattered from the outer belt to the exozodi region. We hypothesise that this increase is sufficient to sustain the observed exozodi on Gyr timescales. No correlation between observations of an outer belt and an exozodi is required for this scenario to work, as the outer belt may be too faint to detect. If planetesimal driven migration does explain the observed exozodi, this work suggests that the presence of an exozodi indicates the presence of outer planets and a planetesimal belt. Accepted by MNRAS http://arxiv.org/pdf/1404.2606

Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-Lived Ra- dioisotopes with a . III. Rotating Three Dimensional Cloud Cores A. P. Boss1 and S. A. Keiser1 1 DTM, Carnegie Institution, 5241 Broad Branch Road, NW, Washington, DC 20015-1305, USA E-mail contact: aboss at carnegiescience.edu A key test of the triggering and injection hypothesis for the origin of the solar system’s short-lived radioiso- topes is to reproduce the inferred initial abundances of these isotopes. We present here the most detailed models to date of the shock wave triggering and injection process, where shock waves with varied properties strike fully three dimensional, rotating, dense cloud cores. The models are calculated with the FLASH adaptive mesh hydrodynamics code. Three different outcomes can result: triggered collapse leading to fragmentation into a multiple protostar system; triggered collapse leading to a single protostar embedded in a protostellar disk; or failure to undergo dynamic collapse. Shock wave material is injected into the collapsing clouds through Rayleigh-Taylor fingers, resulting in initially inho- mogeneous distributions in the and protostellar disks. Cloud rotation about an axis aligned with the shock propagation direction does not increase the injection efficiency appreciably, as the shock parameters were chosen to be optimal for injection even in the absence of rotation. For a shock wave from a core-collapse supernova, the dilution factors for supernova material are in the range of ∼ 10−4 to ∼ 3 × 10−4, in agreement with recent laboratory estimates of the required amount of dilution for 60Fe and 26Al. We conclude that a type II supernova remains as a promising candidate for synthesizing the solar system’s short-lived radioisotopes shortly before their injection into the presolar cloud core by the supernova’s remnant shock wave. Accepted by ApJ http://home.dtm.ciw.edu/users/boss/ftp/triggerIII.pdf http://arxiv.org/pdf/1404.7190

Temperaments of young stars: rapid mass-accretion rate changes in T Tauri and Herbig Ae stars Grainne Costigan1,2,3, Jorick S. Vink2, Aleks Scholz1,4, Tom Ray1 and Leonardo Testi3,5 1 Dublin Institute for Advanced Studies, Ireland 2 Armagh Observatory, Northern Ireland 3 European Southern Observatory, Germany 4 School of Physics & Astronomy, University of St. Andrews, Scotland 5 INAF-Osservatorio Astrofisico di Arcetri, Italy; Excellence Cluster , Germany E-mail contact: costigag at gmail.com Variability in emission lines is a characteristic feature in young stars and can be used as a tool to study the physics of the accretion process. Here we present a study of Hα variability in 15 T Tauri and Herbig Ae stars (K7 - B2) over a wide range of time windows, from minutes, to hours, to days, and years. We assess the variability using linewidth measurements and the time series of line profiles. All objects show gradual, slow profile changes on time-scales of days. In addition, in three cases there is evidence for rapid variations in Hα with typical time-scales of 10 min, which occurs in 10% of the total covered observing time. The mean accretion-rate changes, inferred from the line fluxes,are 0.01 - 0.07 dex for time-scales of < 1 hour, 0.04 - 0.4 dex for time-scales of days, and 0.13 - 0.52 dex for time-scales of years. In Costigan et al. (2012) we derived an upper limit finding that the intermediate (days) variability dominated over

15 longer (years) variability. Here our new results, based on much higher cadence observations, also provide a lower limit to accretion-rate variability on similar time-scales (days), thereby constraining the accretion rate variability physics in a much more definitive way. A plausible explanation for the gradual variations over days is an asymmetric accretion flow resulting in a rotational modulation of the accretion-related emission, although other interpretations are possible as well. In conjunction with our previous work, we find that the time-scales and the extent of the variability is similar for objects ranging in mass from ∼ 0.1 to ∼5 M⊙. This confirms that a single mode of accretion is at work from T Tauri to Herbig Ae stars – across a wide range of stellar masses. Accepted by MNRAS http://adsabs.harvard.edu/pdf/2014arXiv1403.4088C

A First-Look Atmospheric Modeling Study of the Young Directly-Imaged Planet-Mass Companion, ROXs 42Bb Thayne Currie1, Adam Burrows2, and Sebastian Daemgen1 1 Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, ON, Canada 2 Department of Astrophysical Sciences, Princeton University, USA E-mail contact: tcurrie at cfa.harvard.edu ′ We present and analyze JKsL photometry and our previously published H-band photometry and K-band spec- troscopy for ROXs 42Bb, an object Currie et al. (2014) first reported as a young directly imaged planet-mass com- panion. ROXs 42Bb exhibits IR colors redder than field L dwarfs but consistent with other planet-mass companions. From the H2O-2 spectral index, we estimate a spectral type of L0 ± 1; weak detections/non-detections of the CO bandheads, Na I, and Ca I support evidence for a young, low surface object primarily derived from the H2(K) index. ROXs 42Bb’s photometry/K-band spectrum are inconsistent with limiting cases of dust-free atmospheres (COND) and marginally inconsistent with the AMES/DUSTY models and the BT-SETTL models. However, ROXS 42Bb data are simultaneously fit by atmosphere models incorporating several micron-sized dust grains entrained in thick clouds, although further modifications are needed to better reproduce the K-band spectral shape. ROXs 42Bb’s best-estimated temperature is Teff ∼ 1950–2000 K, near the low end of the empirically-derived range in Currie et al. (2014). For an age of ∼ 1–3 Myr and considering the lifetime of the protostar phase, ROXs 42Bb’s luminosity of +3 log(L/L⊙) ∼−3.07 ± 0.07 implies a mass of 9−3 MJ, making it one of the lightest planetary mass objects yet imaged. Accepted by ApJ http://arxiv.org/pdf/1404.0131

Molecular Gas Clumps from the Destruction of Icy Bodies in the β Pictoris W.R.F. Dent1, M. C. Wyatt2, A. Roberge3, J.-C. Augereau4, S. Casassus5, S. Corder1, J.S. Greaves6, I. de Gregorio-Monsalvo1, A. Hales1, A.P. Jackson2, A. Meredith Hughes7, A.-M. Lagrange4, B. Matthews8, and D. Wilner9 1 ALMA Santiago Central Offices, Alonso de C´ordova 3107, Vitacura, Casilla 763 0355, Santiago, Chile 2 Institute of Astronomy Madingley Road, Cambridge CB3 0HA, UK 3 and Stellar Astrophysics Lab, NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA 4 UJF-Grenoble 1 / CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble (IPAG), UMR 5274, Greno- ble, F-38041, France 5 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 6 Dept. of Astronomy, University of St. Andrews, North Haugh, St. Andrews, UK 7 Wesleyan University Department of Astronomy, Van Vleck Observatory, 96 Foss Hill Drive, Middletown, CT 06459, USA 8 National Research Council of Canada, Herzberg Astronomy & Astrophysics Programs, 5701 West Saanich Road, Victoria, BC, Canada, V9E 2E7, and Department of Physics & Astronomy, University of Victoria, Finnerty Road, Victoria, BC, V8P 5C2, Canada 9 Smithsonian Astrophysical Observatory, 60 Garden St., MS 42, Cambridge, MA 02138 USA E-mail contact: wdent at alma.cl

16 Many stars are surrounded by disks of dusty debris formed in the collisions of , and dwarf planets. But is gas also released in such events? Observations at submm wavelengths of the archetypal debris disk around β Pictoris show that 0.3% of a mass of monoxide orbits in its debris belt. The gas distribution is highly asymmetric, with 30% found in a single clump 85 AU from the star, in a plane closely aligned with the orbit of the inner planet, β Pic b. This gas clump delineates a region of enhanced collisions, either from a mean motion resonance with an unseen , or from the remnants of a collision of -mass planets. Accepted by Science http://arxiv.org/pdf/1404.1380

GG Tau: the fifth element E. Di Folco1,2, A. Dutrey1,2, J.-B. Le Bouquin3, S. Lacour4, J.-P. Berger5, R. K¨ohler6, S. Guilloteau1,2, V. Pi´etu7, J. Bary8, T. Beck9, H. Beust3, and E. Pantin10 1 Univ. Bordeaux, Laboratoire d’Astrophysique de Bordeaux, UMR 5804, F-33270, Floirac, France 2 CNRS, LAB, UMR 5804, F-33270 Floirac, France 3 UJF-Grenoble 1/CNRS-INSU, Institut de Plan´etologie et d’Astrophysique de Grenoble UMR 5274, F-38041, Greno- ble, France 4 LESIA, CNRS/UMR-8109, Observatoire de Paris, UPMC, Universit´e Paris Diderot, 5 place J. Janssen, F-92195, Meudon, France 5 European Southern Observatory, D-85748, Garching by M¨unchen, Germany 6 Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, D-69117 Heidelberg, Germany 7 IRAM, 300 rue de la piscine, F-38406 Saint-Martin d’H´eres, France 8 Department of Physics and Astronomy, Colgate University, 13 Oak Drive, Hamilton, NY 13346, USA 9 Science Institute, 3700 San Martin Dr. Baltimore, MD 21218, USA 10 Laboratoire AIM, CEA/DSM - CNRS - Universit Paris Diderot, IRFU/SAP, F-91191, Gif-sur-Yvette, France E-mail contact: emmanuel.difolco at obs.u-bordeaux1.fr We aim at unveiling the observational imprint of physical mechanisms that govern planetary formation in young, multiple systems. In particular, we investigate the impact of tidal truncation on the inner circumstellar disks. We observed the emblematic system GG Tau at high-angular resolution: a hierarchical quadruple system composed of low-mass T Tauri binary stars surrounded by a well-studied, massive circumbinary disk in Keplerian rotation. We used the near-IR 4-telescope combiner PIONIER on the VLTI and sparse-aperture-masking techniques on VLT/NaCo to probe this proto- at sub-AU scales. We report the discovery of a significant closure-phase signal in H and Ks bands that can be reproduced with an additional low-mass companion orbiting GG Tau Ab, at a (projected) separation ρ = 31.7 ± 0.2 mas (4.4 au) and P A = 219.6 ± 0.3◦. This finding offers a simple explanation for several key questions in this system, including the missing-stellar-mass problem and the asymmetry of continuum emission from the inner dust disks observed at millimeter wavelengths. Composed of now five co-eval stars with 0.02 ≤ M∗ ≤ 0.7 M⊙, the quintuple system GG Tau has become an ideal test case to constrain models at young ages (few 106 yr). Accepted by A&A http://arxiv.org/pdf/1404.2205

Characterizing the structure of diffuse emission in Hi-GAL maps D. Elia1, F. Strafella2, N. Schneider3, R. Paladini4, R. Vavrek5, Y. Maruccia2, S. Molinari1, S. Pezzuto1, A. Noriega-Crespo6,5, K.L.J. Rygl7, A.M. Di Giorgio1, A. Traficante8, E. Schisano4, L. Calzoletti9,M. Pestalozzi1, S.J. Liu1, P. Natoli10,11,9,12, M. Huang13, P. Martin14, Y. Fukui15 and T. Hayakawa15 1 IAPS-INAF, Via Fosso del Cavaliere 100, 00133 Roma, Italy 2 Dipartimento di Matematica e Fisica, Universit del Salento, CP 193, 73100 Lecce, Italy 3 Univ. Bordeaux, LAB, CNRS, UMR 5804, 33270, Floirac, France 4 Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA 5 Herschel Science Centre, European Space Astronomy Centre, Villafranca del Castillo. Apartado de Correos 78,

17 28080 Madrid, Spain 6 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 7 Research and Scientific Support Department, European Space Agency (ESA-ESTEC), PO Box 299, 2200 AG, Noordwijk, The Netherlands 8 Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK 9 Agenzia Spaziale Italiana Science Data Center, c/o ESRIN, via , 00044 Frascati, Italy 10 Dipartimento di Fisica e Science della Terra, Universit di Ferrara Via Saragat, 1, 44100 Ferrara, Italy 11 INFN, Sezione di Ferrara, via Saragat 1, 44100 Ferrara, Italy 12 INAF-IASF Bologna, Via P. Gobetti 101, 40129, Bologna 13 National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China 14 Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada 15 Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan E-mail contact: davide.elia at iaps.inaf.it We present a study of the structure of the Galactic through the Delta-variance technique, related to the power spectrum and the fractal properties of infrared/sub-mm maps. Through this method, it is possible to provide quantitative parameters which are useful to characterize different morphological and physical conditions, and to better constrain the theoretical models. In this respect, the Herschel Infrared Galactic Plane Survey carried out at five photometric bands from 70 to 500 µm constitutes an unique database for applying statistical tools to a variety of regions across the Milky Way. In this paper, we derive a robust estimate of the power-law portion of the power spectrum of four contiguous 2◦ × 2◦ Hi-GAL tiles located in the third Galactic quadrant (217◦ <ℓ< 225◦, −2◦

An Optical Spectroscopic Study of T Tauri Stars. I. Photospheric Properties Gregory J. Herczeg1 and Lynne A. Hillenbrand2 1 Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, HaiDian Qu, Beijing 100871, China 2 Caltech, 1200 East California Blvd, Pasadena, CA 91125, USA E-mail contact: gherczeg1 at gmail.com Estimates of the mass and age of young stars from their location in the HR diagram are limited by not only the typical observational uncertainties that apply to field stars, but also by large systematic uncertainties related to circumstellar phenomena. In this paper, we analyze flux calibrated optical spectra to measure accurate spectral types and extinctions of 283 nearby T Tauri stars. The primary advances in this paper are (1) the incorporation of a simplistic accretion continuum in optical spectral type and extinction measurements calculated over the full optical wavelength range and (2) the uniform analysis of a large sample of stars. Comparisons between the non-accreting TTS photospheric templates and stellar models are used to derive conversions from spectral type to temperature. Differences between spectral types can be subtle and difficult to discern, especially when accounting for accretion and extinction. The spectral types measured here are mostly consistent with spectral types measured over the past decade. However, our new spectral types are 1-2 subclasses later than literature spectral types for the original members of the TWA and are discrepant with literature values for some well known Taurus CTTSs. Our extinction measurements are consistent with other optical extinction measurements but are typically 1 mag lower than

18 nIR measurements, likely the result of methodological differences and the presence of nIR excesses in most CTTSs. As an illustration of the impact of accretion, SpT, and extinction uncertainties on the HR diagrams of young clusters, we find that the resulting luminosity spread of stars in the TWA is 15-30%. The luminosity spread in the TWA and previously measured for binary stars in Taurus suggests that for a majority of stars, protostellar accretion rates are not large enough to significantly alter the subsequent evolution. Accepted by ApJ http://xxx.lanl.gov/pdf/1403.1675

Protoplanetary dust porosity and FU Orionis Outbursts: Solving the mystery of ’s missing volatiles Alexander Hubbard1 and Denton S. Ebel2 1 Department of Astrophysics, American Museum of Natural History, New York,NY 10024-5192, USA 2 Department of Earth and Planetary Sciences, American Museum of Natural History, New York, NY 10024-5192, USA E-mail contact: ahubbard at amnh.org The Earth is known to be depleted in volatile lithophile elements in a fashion that defies easy explanation. We resolve this anomaly with a model that combines the porosity of collisionally grown dust grains in protoplanetary disks with heating from FU Orionis events that dramatically raise protoplanetary disk temperatures. The heating from an FU Orionis event alters the aerodynamical properties of the dust while evaporating the volatiles. This causes the dust to settle, abandoning those volatiles. The success of this model in explaining the elemental composition of the Earth is a strong argument in favor of highly porous collisionally grown dust grains in protoplanetary disks outside our Solar System. Further, it demonstrates how thermal (or condensation based) alterations of dust porosity, and hence aerodynamics, can be a strong factor in planet formation, leading to the onset of rapid gravitational instabilities in the dust disk and the subsequent collapse that forms planetesimals. Accepted by Icarus http://arxiv.org/pdf/1404.3995

TADPOL: A 1.3 mm Survey of Dust Polarization in Star-forming Cores and Regions Charles L. H. Hull1, Richard L. Plambeck1, Woojin Kwon13, Geoffrey C. Bower1,18, John M. Carpenter2, Richard M. Crutcher4, Jason D. Fiege9, Erica Franzmann9, Nicholas S. Hakobian4, Carl Heiles1, Mar- tin Houde10,3, A. Meredith Hughes14, James W. Lamb2, Leslie W. Looney4, Daniel P. Marrone15, Brenda C. Matthews11,12, Thushara Pillai2, Marc W. Pound5, Nurur Rahman16, G¨oran Sandell8, Ian W. Stephens4,17, John J. Tobin7, John E. Vaillancourt8, N. H. Volgenau6, and Melvyn C. H. Wright1 1 Astronomy Department & Laboratory, University of California, Berkeley, CA 94720-3411, USA 2 Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., MC 249-17, Pasadena, CA 91125, USA 3 Division of Physics, Mathematics, & Astronomy, California Institute of Technology, Pasadena, CA 91125, USA 4 Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W Green Street, Urbana, IL 61801, USA 5 Astronomy Department & Laboratory for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742, USA 6 Combined Array for Research in Millimeter-wave Astronomy, Owens Valley Radio Observatory, P.O. Box 968, Big Pine, CA 93513, USA 7 National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903, USA 8 SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, Moffett Field, CA 94035, USA 9 Department of Physics & Astronomy, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada 10 Department of Physics & Astronomy, University of Western Ontario, London, ON, N6A 3K7, Canada 11 Department of Physics & Astronomy, University of Victoria, 3800 Finnerty Rd., Victoria, BC, V8P 5C2, Canada

19 12 National Research Council of Canada, 5071 West Saanich Rd., Victoria, BC, V9E 2E7, Canada 13 SRON Netherlands Institute for Space Research, Landleven 12, 9747 AD Groningen, The Netherlands 14 Van Vleck Observatory, Astronomy Department, Wesleyan University, 96 Foss Hill Drive, Middletown, CT 06459, USA 15 Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA 16 Physics Department, University of Johannesburg, C1-Lab 140, PO Box 524, Auckland Park 2006, South Africa 17 Institute for Astrophysical Research, Boston University, Boston, MA 02215, USA 18 ASIAA, 645 N. A’ohoku Place, Hilo, HI, 96720, USA E-mail contact: chat at astro.berkeley.edu We present λ 1.3 mm CARMA observations of dust polarization toward 30 star-forming cores and 8 star-forming regions from the TADPOL survey. We show maps of all sources, and compare the ∼ 2.5′′ resolution TADPOL maps with ∼ 20′′ resolution polarization maps from single-dish submillimeter telescopes. Here we do not attempt to interpret the detailed B-field morphology of each object. Rather, we use average B-field orientations to derive conclusions in a statistical sense from the ensemble of sources, bearing in mind that these average orientations can be quite uncertain. We discuss three main findings: (1) A subset of the sources have consistent magnetic field (B-field) orientations between large (∼ 20′′) and small (∼ 2.5′′) scales. Those same sources also tend to have higher fractional polarizations than the sources with inconsistent large-to-small-scale fields. We interpret this to mean that in at least some cases B-fields play a role in regulating the infall of material all the way down to the ∼ 1000 AU scales of protostellar envelopes. (2) Outflows appear to be randomly aligned with B-fields; although, in sources with low polarization fractions there is a hint that outflows are preferentially perpendicular to small-scale B-fields, which suggests that in these sources the fields have been wrapped up by envelope rotation. (3) Finally, even at ∼ 2.5′′ resolution we see the so-called “polarization hole” effect, where the fractional polarization drops significantly near the total intensity peak. All data are publicly available in the electronic edition of this article. Accepted by the Astrophysical Journal Supplement

Subarcsecond Imaging of the NGC 6334 I(N) Protocluster: Two Dozen Compact Sources and a Massive Disk Candidate T. R. Hunter1, C. L. Brogan1, C. J. Cyganowski2,3 and K. H. Young2 1 National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA 22903, USA 2 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA 3 SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS, UK E-mail contact: thunter at nrao.edu Using the SMA and VLA, we have imaged the massive protocluster NGC 6334 I(N) at high angular resolution (0.5′′ ∼ 650 AU) from 6 cm to 0.87 mm, detecting 18 new compact continuum sources. Three of the new sources are coincident with previously-identified H2O masers. Together with the previously-known sources, these data bring the number of likely protocluster members to 25 for a protostellar density of ∼ 700 pc−3. Our preliminary measurement of the Q-parameter of the minimum spanning tree is 0.82 – close to the value for a uniform volume distribution. All of the (nine) sources with detections at multiple frequencies have SEDs consistent with dust emission, and two (SMA 1b and SMA 4) also have long wavelength emission consistent with a central hypercompact HII region. Thermal emission, including CH3CN, is detected in six sources: LTE model fitting of CH3CN (J=12–11) yields temperatures of 72–373 K, confirming the presence of multiple hot cores. The fitted LSR velocities range from −3.3 to −7.0km s−1, with an unbiased mean square deviation of 2.05 km s−1, implying a protocluster dynamical mass of 410±260 M⊙. From analysis of a wide range of hot core molecules, the kinematics of SMA 1b are consistent with a ◦ rotating, infalling Keplerian disk of diameter 800 AU and enclosed mass of 10-30 M⊙ that is perpendicular (within 1 ) to the large-scale bipolar outflow axis. A companion to SMA 1b at a projected separation of 0.45′′ (590 AU; SMA 1d), which shows no evidence of spectral line emission, is also confirmed. Finally, we detect one 218.4400 GHz and several 229.7588 GHz Class-I CH3OH masers. Accepted by The Astrophysical Journal http://www.cv.nrao.edu/~thunter/papers/ngc6334in2014.pdf

20 A long-term UBVRI photometric study of the pre-main sequence star V350 Cep Sunay Ibryamov1, Evgeni Semkov1 and Stoyanka Peneva1 1 Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences, BG-1784 Sofia, Bulgaria E-mail contact: sibryamov at astro.bas.bg Results from UBVRI optical photometric observations of the pre-main sequence star V350 Cep during the period 2004-2014 are presented in the paper. The star is discovered in 1977 due to the remarkable increase in brightness with more than 5 mag (R). In the previous studies V350 Cep is considered a potential member of the groups of FUors or EXors eruptive variables. Our data suggest that during the period of observations the star keeps its maximum brightness with low amplitude photometric variations. Our conclusion is that V350 Cep is probably an intermediate object between FUors and EXors, similar to V1647 Ori. Accepted by Research in Astronomy and Astrophysics http://arxiv.org/pdf/1404.5902

The effect of on the radii of low-mass pre-main sequence stars R.J. Jackson1 and R.D. Jeffries1 1 Astrophysics Group, Research Institute for the Environment, Physical Sciences and Applied Mathematics, Keele University, Keele, Staffordshire ST5 5BG, UK E-mail contact: r.d.jeffries at keele.ac.uk A polytropic model is used to investigate the effects of dark photospheric spots on the evolution and radii of mag- netically active, low-mass (M < 0.5 M⊙), pre-main sequence (PMS) stars. Spots slow the contraction along Hayashi tracks and inflate the radii of PMS stars by a factor of (1 − β)−N compared to unspotted stars of the same luminosity, where β is the equivalent covering fraction of dark starspots and N ≃ 0.45 ± 0.05. This is a much stronger inflation than predicted by the models of Spruit & Weiss (1986) for main sequence stars with the same beta, where N ∼ 0.2–0.3. These models have been compared to radii determined for very magnetically active K- and M-dwarfs in the young Pleiades and NGC 2516 clusters, and the radii of tidally-locked, low-mass eclipsing binary components. The binary components and ZAMS K-dwarfs have radii inflated by ∼ 10 per cent compared to an empirical radius-luminosity relation that is defined by magnetically inactive field dwarfs with interferometrically measured radii; low-mass M-type PMS stars, that are still on their Hayashi tracks, are inflated by up to ∼ 40 per cent. If this were attributable to starspots alone, we estimate that an effective spot coverage of 0.35 <β< 0.51 is required. Alternatively, global inhi- bition of convective flux transport by dynamo-generated fields may play a role. However, we find greater consistency with the models when comparing the loci of active young stars and inactive field stars in colour-magnitude diagrams, particularly for the highly inflated PMS stars, where the large, uniform temperature reduction required in globally inhibited convection models would cause the stars to be much redder than observed. Accepted by MNRAS http://arxiv.org/pdf/1404.0683

Searching for circumplanetary disks around LkCa 15 Andrea Isella1, Claire J. Chandler2, John M. Carpenter1, Laura M. Perez2, and Luca Ricci1 1 Department of Astronomy, California Institute of Technology, MC 249-17, Pasadena, CA 91125, USA 2 National Radio Astronomy Observatory, PO Box O, Socorro, NM 87801, USA E-mail contact: isella at astro.caltech.edu We present Karl G. Jansky Very Large Array (VLA) observations of the 7 mm continuum emission from the disk surrounding the young star LkCa 15. The observations achieve an angular resolution of 70 mas and spatially resolve the circumstellar emission on a spatial scale of 9 AU. The continuum emission traces a dusty annulus of 45 AU in radius that is consistent with the dust morphology observed at shorter wavelengths. The VLA observations also reveal a compact source at the center of the disk, possibly due to thermal emission from hot dust or ionized gas located

21 within a few AU from the central star. No emission is observed between the star and the dusty ring, and, in particular, at the position of the candidate LkCa 15 b. By comparing the observations with theoretical models for emission, we find that if LkCa 15 b is a massive planet (>5 MJ) accreting at a rate greater −6 −1 than 10 MJ yr , then its circumplanetary disk is less massive than 0.1 MJ, or smaller than 0.4 Hill radii. Similar constraints are derived for any possible circumplanetary disk orbiting within 45 AU from the central star. The mass estimate are uncertain by at least one order of magnitude due to the uncertainties on the mass opacity. Future ALMA −4 observations of this system might be able to detect circumplanetary disks down to a mass of 5 × 10 MJ and as small as 0.2 AU, providing crucial constraints on the presence of giant planets in the act of forming around this young star. Accepted by ApJ http://arxiv.org/pdf/1404.5627

Detectability of Glycine in Solar-type System Precursors Izaskun Jimenez-Serra1, Leonardo Testi1, Paola Caselli2,3 and Serena Viti4 1 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany 2 School of Physics & Astronomy, University of Leeds, LS2 9JT, Leeds, UK 3 Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstr., 85741 Garching, Germany 4 Department of Physics & Astronomy, University College London, Gower Place, WC1E 6BT, London, UK E-mail contact: ijimenez at eso.org

Glycine (NH2CH2COOH) is the simplest amino acid relevant for . Its detection in the interstellar medium is key to understand the formation mechanisms of pre-biotic molecules and their subsequent delivery onto planetary systems. Glycine has extensively been searched for toward hot molecular cores, although these studies did not yield any firm detection. In contrast to hot cores, low-mass star forming regions, and in particular their earliest stages represented by cold pre-stellar cores, may be better suited for the detection of glycine as well as more relevant for the study of pre-biotic chemistry in young Solar System analogs. We present 1D spherically symmetric radiative transfer calculations of the glycine emission expected to arise from the low-mass pre- L1544. vapour has recently been reported toward this core, indicating that a small fraction of the grain mantles in L1544 (∼0.5%) has been injected into the gas phase. Assuming that glycine is photo-desorbed together with water in L1544, and considering a solid abundance of glycine on ices of ∼10−4 with respect to water, our calculations reveal that several glycine lines between 67 GHz and 80 GHz have peak intensities larger than 10 mK. These results show for the first time that glycine could reach detectable levels in cold objects such as L1544. This opens up the possibility to detect glycine, and other pre-biotic species, at the coldest and earliest stages in the formation of Solar-type systems with near-future instrumentation such as the Band 2 receivers of ALMA. Accepted by Astrophysical Journal Letters http://arxiv.org/pdf/1404.5849

Unfolding the Laws of Star Formation: The Density Distribution of Molecular Clouds Jouni Kainulainen1, Christoph Federrath2, and Thomas Henning1 1 Max-Planck-Institute for Astronomy, K¨onigstuhl 17, 69117 Heidelberg, Germany 2 Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, Vic 3800, Australia E-mail contact: jtkainul at mpia.de The formation of stars shapes the structure and evolution of entire . The rate and efficiency of this process are affected substantially by the density structure of the individual molecular clouds in which stars form. The most fundamental measure of this structure is the probability density function of volume densities (ρ-PDF), which determines the star formation rates predicted with analytical models. This function has remained unconstrained by observations. We have developed an approach to quantify ρ-PDFs and establish their relation to star formation. The ρ-PDFs instigate a density threshold of star formation and allow us to quantify the star formation efficiency above it. The ρ-PDFs provide new constraints for star formation theories and correctly predict several key properties of the star- forming interstellar medium.

22 Accepted by Science http://arxiv.org/pdf/1404.2722

Herschel evidence for disk flattening or gas depletion in transitional disks J.T. Keane1, I. Pascucci1, C. Espaillat2, P. Woitke3, S. Andrews4, I. Kamp5, W.-F. Thi6, G. Meeus7, and W.R.F. Dent8 1 Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA 2 Department of Astronomy, Boston University, Boston, MA 02215, USA 3 SUPA, School of Physics & Astronomy, University of St. Andrews, North Haugh, St. Andrews, KY16 9SS, UK 4 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA 5 Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, The Netherlands 6 Universit´eJoseph Fourier Grenoble-1, CNRS-INSU, Institut de Plan´etologie et d’Astrophysique (IPAG) UMR 5274, 38041 Grenoble, France 7 Universidad Autonoma de Madrid, Dpt. Fisica Teorica, Campus Cantoblanco, 28049 Madrid, Spain 8 ALMA SCO, Alonso de Cordova 3107, Vitacura, Santiago, Chile E-mail contact: jkeane at lpl.arizona.edu Transitional disks are protoplanetary disks characterized by reduced near- and mid-infrared emission with respect to full disks. This characteristic spectral energy distribution indicates the presence of an optically thin inner cavity within the dust disk believed to mark the disappearance of the primordial massive disk. We present new Herschel Space Observatory PACS spectra of [OI] 63 µm for 21 transitional disks. Our survey complements the larger Herschel GASPS program “Gas in Protoplanetary Systems” (Dent et al. 2013) by quadrupling the number of transitional disks observed with PACS at this wavelength. [OI] 63 µm traces material in the outer regions of the disk, beyond the inner cavity of most transitional disks. We find that transitional disks have [OI] 63 µm line luminosities two times fainter than their full disk counterparts. We self consistently determine various stellar properties (e.g. bolometric luminosity, FUV excess, etc.) and disk properties (e.g. disk dust mass, etc.) that could influence the [OI] 63 µm line luminosity and we find no correlations that can explain the lower [OI] 63 µm line luminosities in transitional disks. Using a grid of thermo-chemical protoplanetary disk models, we conclude that either transitional disks are less flared than full disks or they possess lower gas-to-dust ratios due to a depletion of gas mass. This result suggests that transitional disks are more evolved than their full disk counterparts, possibly even at large radii. Accepted by ApJ http://arxiv.org/pdf/1404.0709

Rolling friction of adhesive microspheres S. Krijt1, C. Dominik2,3 and A.G.G.M. Tielens1 1 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 2 Astronomical Institute ’Anton Pannekoek’, University of Amsterdam, PO Box 94249, 1090 GE Amsterdam, The Netherlands 3 Afdeling Sterrenkunde, Radboud Universiteit Nijmegen, Postbus 9010, 6500 GL, Nijmegen, The Netherlands E-mail contact: krijt at strw.leidenuniv.nl The rolling friction of adhesive microspheres is an important quantity as it determines the strength and stability of larger aggregates. Current models predict rolling forces that are 1 to 2 orders of magnitude smaller than observed experimentally. Starting from the well-known Johnson-Kendall-Roberts (JKR) contact description, we derive an analytical theory for the rolling friction based on the concept of adhesion hysteresis, e.g. a difference in apparent surface energies for opening/closing cracks. We show how adhesion hysteresis causes the distribution within the contact to become asymmetrical, leading to an opposing torque. Analytical expressions are derived relating the size of the hysteresis, the rolling torque, and the rolling displacement, ξ. We confirm the existence of a critical rolling displacement for the onset of rolling, the size of which is set by the amount of adhesion hysteresis and the size of the contact area. We demonstrate how the developed theory is able to explain the large rolling forces and particle-size dependence observed experimentally. Good agreement with experimental results is achieved for adhesion hysteresis

23 values of (∆γ/γ) ≃ 3 for polystyrene, and (∆γ/γ) ≃ 0.5 for silicates, at crack propagation rates of 0.1 µm s−1 and 1 − 10 µm s−1 respectively. Accepted by Journal of Physics D: Applied Physics http://iopscience.iop.org/0022-3727/47/17/175302/

The Dependence of Protostellar Luminosity on Environment in the -X Star- Forming Complex E. Kryukova1, S. T. Megeath1, J. L. Hora2, R. A. Gutermuth3, S. Bontemps4,5, K. Kraemer6,M. Hennemann7, N. Schneider4,5, Howard A. Smith2 and F. Motte7 1 Ritter Astrophysical Observatory, Department of Physics and Astronomy, University of Toledo, Toledo, OH, USA 2 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA 3 Department of Astronomy, University of Massachusetts, Amherst, MA, USA 4 Univ. Bordeaux, LAB, UMR 5804, F-33270, Floirac, France 5 CNRS, LAB, UMR 5804, F-33270, Floirac, France 6 Institute for Scientific Research, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA 7 Laboratoire AIM, CEA/IRFU - CNRS/INSU - Universit´eParis Diderot, Service d’Astrophysique, Bˆat. 709, CEA- Saclay, 91191 Gif-sur-Yvette Cedex, France E-mail contact: tommegeath at gmail.com The Cygnus-X star-forming complex is one of the most active regions of low and high mass star formation within 2 kpc of the Sun. Using mid-infrared photometry from the IRAC and MIPS Spitzer Cygnus-X Legacy Survey, we have identified over 1800 protostar candidates. We compare the protostellar luminosity functions of two regions within Cygnus-X: CygX-South and CygX-North. These two clouds show distinctly different morphologies suggestive of dissimilar star-forming environments. We find the luminosity functions of these two regions are statistically different. Furthermore, we compare the luminosity functions of protostars found in regions of high and low stellar density within Cygnus-X and find that the luminosity function in regions of high stellar density is biased to higher luminosities. In total, these observations provide further evidence that the luminosities of protostars depend on their natal environment. We discuss the implications this dependence has for the star formation process. Accepted by Astronomical Journal Main article at: http://astro1.physics.utoledo.edu/~megeath/cygnus_x/ms_final.pdf Data table at: http://astro1.physics.utoledo.edu/~megeath/cygnus_x/photometry_table.pdf

Stellar dynamics in gas: The role of gas damping Nathan W.C. Leigh1,2, Alessandra Mastrobuono Battisti3, Hagai B. Perets3,4, and Torsten B¨oker5 1 Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB T6G 2E1, Canada 2 Department of Astrophysics, American Museum of Natural History, Central Park West and 79th Street, New York, NY 10024, USA 3 Physics Department, Technion: Israel Institute of Technology, Haifa, Israel 32000 4 Deloro Fellow 5 European Space Agency, Space Science Department, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands E-mail contact: nleigh at ualberta.ca In this paper, we consider how gas damping affects the dynamical evolution of gas-embedded star clusters. Using a simple three-component (i.e. one gas and two stellar components) model, we compare the rates of mass segregation due to two-body relaxation, accretion from the interstellar medium, and gas dynamical friction in both the supersonic and subsonic regimes. Using observational data in the literature, we apply our analytic predictions to two different astrophysical environments, namely galactic nuclei and young open star clusters. Our analytic results are then tested using numerical simulations performed with the NBSymple code, modified by an additional deceleration term to model the damping effects of the gas. The results of our simulations are in reasonable agreement with our analytic predictions, and demonstrate that gas

24 damping can significantly accelerate the rate of mass segregation. A stable state of approximate energy equilibrium cannot be achieved in our model if gas damping is present, even if Spitzer’s Criterion is satisfied. This instability drives the continued dynamical decoupling and subsequent ejection (and/or collisions) of the more massive population. Unlike two-body relaxation, gas damping causes overall cluster contraction, reducing both the core and half-mass radii. If the cluster is mass segregated (and/or the gas density is highest at the cluster centre), the latter contracts faster than the former, accelerating the rate of core collapse. Accepted by MNRAS http://arxiv.org/pdf/1404.0379

Herschel-Planck dust optical-depth and column-density maps: I. Method description and results for Orion Marco Lombardi1,4, Herv´eBouy2, Jo˜ao Alves3, and Charles J. Lada4 1 University of Milan, Department of Physics, via Celoria 16, I-20133 Milan, Italy 2 Centro de Astrobiolog´ıa, INTA-CSIC, PO Box 78, 28691 Villanueva de la Ca˜nada, Madrid, Spain 3 University of Vienna, T¨urkenschanzstrasse 17, 1180 Vienna, Austria 4 Harvard-Smithsonian Center for Astrophysics, Mail Stop 72, 60 Garden Street, Cambridge, MA 02138 E-mail contact: marco.lombardi at unimi.it We present high-resolution, high dynamic range column-density and color-temperature maps of the Orion complex using a combination of Planck dust-emission maps, Herschel dust-emission maps, and 2MASS NIR dust-extinction maps. The column-density maps combine the robustness of the 2MASS NIR extinction maps with the resolution and coverage of the Herschel and Planck dust-emission maps and constitute the highest dynamic range column-density 20 −2 maps ever constructed for the entire Orion complex, covering 0.01 mag < AK < 30 mag, or 2 × 10 cm

Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N J. Malinen1, M. Juvela1, V.-M. Pelkonen2,1, and M.G. Rawlings3 1 Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland 2 Finnish Centre for Astronomy with ESO, University of Turku, V¨ais¨al¨antie 20, FI-21500 Piikki¨o, Finland 3 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA E-mail contact: johanna.malinen at helsinki Mapping of near-infrared (NIR) scattered light is a recent method for the study of interstellar clouds, complementing other, more commonly used methods, like dust emission and extinction. Our goal is to study the usability of this method on larger scale, and compare the properties of a filament using NIR scattering and other methods. We also study the radiation field and differences in grain emissivity between diffuse and dense areas. We have used scattered J, H, and K band surface brightness WFCAM-observations to map filament TMC-1N in Taurus, covering an area of 1◦ × 1◦ corresponding to ∼ (2.44 pc)2. We have converted the data into optical depth and compared the results with NIR extinction and Herschel observations of submm dust emission. We see the filament in scattered light in all three NIR bands. We note that our WFCAM observations in TMC-1N show notably lower intensity than previous results in using the same method. We show that 3D radiative transfer simulations predict similar scattered surface brightness levels as seen in the observations. However, changing the assumptions about the background can change the results of simulations notably. We derive emissivity by using optical depth in the J band as an independent tracer of column density. We obtain opacity σ(250 µm) values 1.7–2.4 × 10−25 cm2/H, depending on assumptions of

25 the extinction curve, which can change the results by over 40%. These values are twice as high as obtained for diffuse areas, at the lower limit of earlier results for denser areas. We show that NIR scattering can be a valuable tool in making high resolution maps. We conclude, however, that NIR scattering observations can be complicated, as the data can show relatively low-level artefacts. This suggests caution when planning and interpreting the observations. Accepted by A&A http://arxiv.org/pdf/1404.2539

On the steady state collisional evolution of debris disks around M dwarfs Etienne Morey1and Jean-Fran¸cois Lestrade2 1 Observatoire de Paris - LERMA, 61 Av. de l’Observatoire, F-75014, Paris, France 2 Observatoire de Paris - LERMA, CNRS, 61 Av. de l’Observatoire, F-75014, Paris, France E-mail contact: jean-francois.lestrade at obspm.fr Debris disks have been found primarily around intermediate and stars (spectral types A–K), but rarely around low-mass M-type stars. This scarcity of detections in M star surveys can be confronted with the predictions of the steady state collisional evolution model. First, we determine the parameters of the disk population evolved with this model and fit to the distribution of the fractional dust luminosities measured in the surveys of A- and FGK-type stars observed by the infrared satellite Spitzer. Thus, in our approach, we stipulate that the initial disk mass distribution is bimodal and that only high-mass collisionally-dominated disks are detected. The best determined parameter is the diameter Dc of the largest planetesimals in the collisional cascade of the model, which ranges between 2 and 60 km, consistently for disks around A- and FGK-type stars. Second, we assume that the same disk population surrounds the M dwarfs that have been the subjects of debris disk searches in the far-infrared with Spitzer and at submillimeter wavelengths with radiotelescopes. We find, in the framework of our study, that this disk population, which has been fit to the AFGK data, is still consistent with the observed lack of disks around M dwarfs with Spitzer. Accepted by A&A http://arxiv.org/pdf/1404.1954

A multiple system of high-mass YSOs surrounded by disks in NGC7538 IRS1: Gas Dynamics on Scales 10–700 AU from CH3OH Maser and NH3 Thermal Lines Luca Moscadelli1 and Ciriaco Goddi2 1 INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy 2 Joint Institute for VLBI in Europe, Postbus 2, NL-7990 AA Dwingeloo, the Netherlands E-mail contact: goddi at jive.nl

NGC7538 IRS1 is claimed to be a high-mass (YSO) with 30 M⊙, surrounded by a rotating Keplerian-disk, probed by a linear distribution of methanol masers. The YSO is also powering a strong compact H II region and an ionized wind, and is driving at least one molecular outflow. The axes orientations of the different structures (ionized gas, outflow, and disk) are however misaligned with each other, which led to different competing models proposed to explain individual structures. We investigate the 3D kinematics and dynamics of circumstellar gas with very high linear resolution, from tens to 1500 AU, with the ultimate goal of building a comprehensive dynamical model for what is considered the best high-mass accretion disk candidate around an O-type young star in the northern hemisphere. We use high-angular resolution observations of 6.7 GHz CH3OH masers with the EVN, NH3 inversion lines with the JVLA B-Array, and radio continuum with the VLA A-Array. In particular, we employed four different observing epochs of EVN data at 6.7 GHz, spanning almost eight years, which enabled us to measure, besides line- of-sight (l.o.s.) velocities and positions (as done in previous works), also l.o.s. accelerations and proper motions of CH3OH masers. In addition, we imaged highly-excited NH3 inversion lines, from (6,6) to (13,13), which enabled us to probe the hottest molecular gas very close to the exciting source(s). We confirm previous results that five 6.7 GHz maser clusters (labeled from ”A” to ”E”) are distributed over a region extended N–S across ≈1500 AU, and are associated with three components of the radio continuum emission. We propose that these maser clusters identify three individual high-mass YSOs in NGC7538 IRS1, named IRS1a (associated with clusters ”B” and ”C”), IRS1b (associated with cluster ”A”), and IRS1c (associated with cluster ”E”). We model the masers in both clusters ”A” and

26 ”B”+”C” in terms of an edge-on disk in centrifugal equilibrium. Based on our modeling, masers of clusters ”B”+”C” may trace a quasi-Keplerian ∼1 M⊙, thin disk, orbiting around a high-mass YSO, IRS1a, of up to ≈25 M⊙. This YSO dominates the bolometric luminosity of the region. The disk traced by the masers of cluster ”A” is both massive < ◦ (∼16 M⊙ inside a radius of ≈500 AU) and thick (opening angle ≈ 45 ), and the mass of the central YSO, IRS1b, is constrained to be at most a few M⊙. Towards cluster ”E”, NH3 and 6.7 GHz masers trace more quiescent dynamics than for the other clusters. The presence of a radio continuum peak suggests that the YSO associated with the cluster ”E”, IRS1c, may be an ionizing, massive YSO as well. The presence of a multiple system of high-mass YSOs naturally explains all the different orientations and disk/outflow structures proposed for the region in previous models. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1404.3957

The formation of the W43 complex: constraining its atomic-to-molecular transition and searching for colliding clouds Fr´ed´erique Motte1, Q. Nguyen Luong2, N. Schneider3, F. Heitsch4, S. Glover5, P. Carlhoff6, T. Hill7, S. Bontemps3, P. Schilke6, F. Louvet1, M. Hennemann8, P. Didelon1 and H. Beuther8 1 Laboratoire AIM Paris-Saclay, CEA/IRFU - CNRS/INSU - Universit´e Paris Diderot, Service d’Astrophysique, Bˆat. 709, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex, France 2 Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada 3 OASU/LAB-UMR 5804, CNRS/INSU - Universit´eBordeaux 1, 2 rue de l’Observatoire, BP 89, F-33270 Floirac, France 4 Department of Physics and Astronomy, University of North Carolina Chapel Hill, Phillips Hall, Chapel Hill, NC 27599-3255, USA 5 Universit¨at Heidelberg, Zentrum f¨ur Astronomie, Institut f¨ur Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany 6 Physikalisches Institut, Universit¨at zu K¨oln, Z¨ulpicher Str. 77, D-50937 K¨oln, Germany 7 Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile 8 Max-Planck-Institut f¨ur Astronomie, K¨onigsstuhl 17, 69117 Heidelberg, Germany E-mail contact: frederique.motte at cea.fr Numerical simulations have explored the possibility to form molecular clouds through either a quasi-static, self- gravitating mechanism or the collision of gas streams or lower-density clouds. They also quantitatively predict the distribution of matter at the transition from atomic to molecular gases. We aim to observationally test these models by studying the environment of W43, a complex recently identified near the tip of the Galactic long bar. Using Galaxy-wide HI and 12CO 1–0 surveys we searched for gas flowing toward the W43 molecular cloud complex. We also estimated the HI and H2 mass surface densities to constrain the transition from atomic to molecular gas around and within W43. We found three cloud ensembles within the position-velocity diagrams of 12CO and HI gases. They are separated by ∼20 km s−1 along the line of sight and extend into the 13CO velocity structure of W43. Since their velocity gradients are consistent with free-fall, they could be nearby clouds attracted by, and streaming toward, 7 −2 the W43 ∼10 M⊙ potential well. We show that the HI surface density, ΣHI = 45 − 85 M⊙,pc , does not reach any threshold level but increases when entering the 130 pc-wide molecular complex previously defined. This suggests that an equilibrium between H2 formation and photodissociation has not yet been reached. The H2-to-HI ratio measured 3 over the W43 region and its surroundings, RH2 ∼ 3.5±2, is high, indicating that most of the gas is already in molecular form in W43 and in structures several hundreds of parsecs downstream along the Scutum- arm. The W43 molecular cloud complex may have formed, and in fact may still be accreting mass from the agglomeration of clouds. Already in the molecular-dominated regime, most of these clouds are streaming from the Scutum-Centaurus arm. This is in clear disagreement with quasi-static and steady-state models of molecular cloud formation. Accepted by Astronomy & Astrophysics http://arxiv.org/pdf/1404.4404

27 Spatial differences between stars and brown dwarfs: a dynamical origin? Richard J. Parker1,2 and Morten Andersen3 1 Astrophysics Research Institute, Liverpool John Moores University, IC2 Liverpool Science Park, 146 Brownlow Hill, Liverpool, L3 5RF, UK 2 Institute for Astronomy, ETH Z¨urich, Wolfgang-Pauli-Strasse 27, 8093, Z¨urich, Switzerland 3 Institut de Plan´etologie et d’Astrophysique de Grenoble, BP 53, F-38041 Grenoble C´edex 9, France E-mail contact: R.J.Parker at ljmu.ac.uk We use N-body simulations to compare the evolution of spatial distributions of stars and brown dwarfs in young star-forming regions. We use three different diagnostics; the ratio of stars to brown dwarfs as a function of distance from the region’s centre, RSSR, the local surface density of stars compared to brown dwarfs, ΣLDR, and we compare the global spatial distributions using the ΛMSR method. From a suite of twenty initially statistically identical simulations, 6/20 attain RSSR << 1 and ΣLDR << 1 and ΛMSR << 1, indicating that dynamical interactions could be responsible for observed differences in the spatial distributions of stars and brown dwarfs in star-forming regions. However, many simulations also display apparently contradictory results - for example, in some cases the brown dwarfs have much lower local densities than stars (ΣLDR << 1), but their global spatial distributions are indistinguishable (ΛMSR = 1) and the relative proportion of stars and brown dwarfs remains constant across the region (RSSR = 1). Our results suggest that extreme caution should be exercised when interpreting any observed difference in the spatial distribution of stars and brown dwarfs, and that a much larger observational sample of regions/clusters (with complete mass functions) is necessary to investigate whether or not brown dwarfs form through similar mechanisms to stars. Accepted by MNRAS http://arxiv.org/pdf/1403.7053

Collective outflow from a small multiple stellar system Thomas Peters1, Pamela D. Klaassen2, Mordecai-Mark Mac Low3,4, Martin Schr¨on4,5, Christoph Federrath6, Michael D. Smith7 and Ralf S. Klessen4 1 Institut f¨ur Theoretische Physik, Universit¨at Z¨urich, Winterthurerstr. 190, CH-8057 Z¨urich, Switzerland 2 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 3 Dept. of Astrophysics, American Museum of Natural History, 79th Street at Central Park West, New York, USA 4 Zentrum f¨ur Astronomie der Universit¨at Heidelberg, Institut f¨ur Theoretische Astrophysik, Albert-Ueberle-Str. 2, D-69120 Heidelberg, Germany 5 Dept. of Computational Hydrosystems, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, D-04318 Leipzig, Germany 6 Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, Vic 3800, Australia 7 Centre for Astrophysics & Space Science, University of Kent, Canterbury, CT2 7NH, England E-mail contact: tpeters at physik.uzh.ch The formation of high-mass stars is usually accompanied by powerful protostellar outflows. Such high-mass outflows are not simply scaled-up versions of their lower-mass counterparts, since observations suggest that the collimation degree degrades with stellar mass. Theoretically, the origins of massive outflows remain open to question because radiative feedback and fragmentation of the accretion flow around the most massive stars, with M > 15 M⊙, may impede the driving of magnetic disk winds. We here present a three-dimensional simulation of the early stages of core fragmentation and massive star formation that includes a subgrid-scale model for protostellar outflows. We find that stars that form in a common accretion flow tend to have aligned outflow axes, so that the individual jets of multiple stars can combine to form a collective outflow. We compare our simulation to observations with synthetic H2 and CO observations and find that the morphology and kinematics of such a collective outflow resembles some observed massive outflows, such as A and DR 21. We finally compare physical quantities derived from simulated observations of our models to the actual values in the models to examine the reliability of standard methods for deriving physical quantities, demonstrating that those methods indeed recover the actual values to within a factor of 2–3. Accepted by ApJ http://arxiv.org/pdf/1404.5463

28 The Origin of Ionized Filaments Within the Orion-Eridanus Andy Pon1,2,3, Doug Johnstone4,3,2, John Bally5, and Carl Heiles6 1 School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK 2 Department of Physics and Astronomy, University of Victoria, PO Box 3055 STN CSC, Victoria BC V8W 3P6, Canada 3 NRC-Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada 4 Joint Astronomy Centre, 660 North Aohoku Place, University Park, Hilo, HI 96720, USA 5 Department of Astrophysical and Planetary Sciences, University of Colorado, UCB 389 CASA, Boulder, CO 80389- 0389, USA 6 Astronomy Department, University of California, 601 Campbell Hall 3411, Berkeley, CA 94720-3411, USA E-mail contact: phyapon at leeds.ac.uk The Orion-Eridanus superbubble, formed by the nearby Orion high mass star-forming region, contains multiple bright Hα filaments on the Eridanus side of the superbubble. We examine the implications of the Hα brightnesses and sizes of these filaments, the Eridanus filaments. We find that either the filaments must be highly elongated along the line of sight or they cannot be equilibrium structures illuminated solely by the Orion star-forming region. The Eridanus filaments may, instead, have formed when the Orion-Eridanus superbubble encountered and compressed a pre-existing, ionized gas cloud, such that the filaments are now out of equilibrium and slowly recombining. Accepted by MNRAS http://arxiv.org/pdf/1404.1917

Imaging polarimetry of the rotating CB67 M.S. Prokopjeva1, A.K. Sen2,3, V.B. Il’in1,4,5, N.V. Voshchinnikov1, and R. Gupta2 1 St. Petersburg State University, Astronomical Institute Universitetskij pr. 28, St.Petersburg, 198504, Russia 2 Inter University Centre for Astronomy and Astrophysics, Ganeshkhind, Pune 411007, India 3 Assam University, Silchar, 788011 India 4 Main (Pulkovo) Astronomical Observatory, Pulkovskoe sh. 65/1, St.Petersburg, 196140, Russia 5 St. Petersburg State University of Aerospace Instrumentation, ul. Bolshaya Morskaya 67, St.Petersburg, 190000, Russia E-mail contact: ari-76 at yandex.ru Polarimetric observations of about 50 stars located in a close vicinity of the Bok globule CB67 having significantly nonspherical shape and rapid rotation are performed. The data obtained are compared with the available observations of this globule at radio and submillimeter wavelengths as well as some theoretical calculations. It is found that the elongation and the rotation moment of CB67 are oriented rather perpendicular to the magnetic fields, which is unusual for Bok globules and is difficult to be explained from the theoretical point of view. Accepted by Journal of Quantitative Spectroscopy & Radiative Transfer http://arxiv.org/pdf/1404.6050

Direct detection of exoplanets in the 3 - 10 micron range with E-ELT/METIS Sascha P. Quanz1, Ian Crossfield2, Michael R. Meyer1, Eva Schmalzl3 and Jenny Held1 1 ETH Zurich, Zurich, Switzerland 2 Max Planck Institute for Astronomy, Heidelberg, Germany 3 Sterrewacht Leiden, Leiden, The Netherlands E-mail contact: sascha.quanz at astro.phys.ethz.ch We quantify the scientific potential for imaging with the Mid-infrared E-ELT Imager and Spectrograph (METIS) foreseen as one of the instruments of the European Extremely Large Telescope (E-ELT). We focus on two main science cases: (1) the direct detection of known planets found by radial velocity (RV) searches; and (2) the direct detection of small (1 – 4 Rearth) planets around the nearest stars. Under the assumptions made in

29 our modeling, in particular on the achievable inner working angle and sensitivity, our analyses reveal that within a reasonable amount of observing time METIS is able to image >20 already known, RV-detected planets in at least one filter. Many more suitable planets with dynamically determined masses are expected to be found in the coming years with the continuation of RV-surveys and the results from the GAIA mission. In addition, by extrapolating the statistics for close-in planets found by Kepler, we expect METIS might detect ∼10 small planets with equilibrium temperatures between 200 - 500 K around the nearest stars. This means that (1) METIS will help constrain atmospheric models for gas giant planets by determining for a sizable sample their luminosity, temperature and ; and (2) METIS might be the first instrument to image a nearby (super-)Earth-sized planet with an equilibrium temperature near that expected to enable liquid water on a planet surface. Accepted by the International Journal of (Cambridge University Press); Invited contribution to an upcoming special issue. http://arxiv.org/pdf/1404.0831

Tracing the ISM magnetic field morphology: The potential of multi-wavelength polar- ization measurements Stefan Reissl1, Sebastian Wolf1 and Daniel Seifried2 1 Institut fr Theoretische Physik und Astrophysik, Christian-Albrechts-Universitt zu Kiel, Leibnizstrae 15, 24098 Kiel, Germany 2 Hamburger Sternwarte, Universitt Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany E-mail contact: sreissl at astrophysik.uni-kiel.de Aims. We present a case study to demonstrate the potential of multi-wavelength polarization measurements. The aim is to investigate the effects that dichroic polarization and thermal re-emission have on tracing the magnetic field in the interstellar medium (ISM). Furthermore, we analyze the crucial influence of imperfectly aligned compact dust grains on the resulting synthetic continuum polarization maps. Methods. We developed an extended version of the well-known 3D Monte-Carlo radiation transport code MC3D for multi-wavelength polarization simulations running on an adaptive grid.We investigated the interplay between radia- tion, magnetic fields and dust grains. Our results were produced by post-processing both ideal density distributions and sophisticated magnetohydrodynamic (MHD) collapse simulations with radiative transfer simulations. We derived spatially resolved maps of intensity, optical depth, and linear and circular polarization at various inclination angles and scales in a wavelength range from 7µm to 1mm. Results. We predict unique patterns in linear and circular polarization maps for different types of density distribu- tions and magnetic field morphologies for test setups and sophisticated MHD collapse simulations. We show that alignment processes of interstellar dust grains can significantly influence the resulting synthetic polarization maps. Multi-wavelength polarization measurements allow one to predict the morphology of the magnetic field inside the ISM. The interpretation of polarization measurements of complex structures still remains ambiguous because of the large variety of the predominant parameters in the ISM. Accepted by A&A 2014 http://arxiv.org/pdf/1404.5286

Gas and dust in the Moving Group as seen by the Herschel Space Obser- vatory P. Riviere-Marichalar1,2, D. Barrado1, B.Montesinos1, G. Duchˆene3,4, H. Bouy1, C. Pinte4, F. Menard4,5, J. Donaldson6, C. Eiroa7, A.V. Krivov8, I. Kamp2, I. Mendigut´ıa9, W.R.F. Dent10, and J. Lillo-Box1 1 Centro de Astrobiolog´ıa(INTACSIC) Depto. Astrof´ısica, POB 78, ESAC Campus, 28691 Villanueva de la Ca˜nada, Spain 2 Kapteyn Astronomical Institute, P.O. Box 800, 9700 AV Groningen, The Netherlands 3 Astronomy Department, University of California, Berkeley CA 94720-3411 USA 4 UJF-Grenoble 1 / CNRS-INSU, Institut de Plan´etologie et d’Astrophysique (IPAG) UMR 5274, Grenoble, F-38041, France

30 5 Laboratorio Franco-Chileno de Astronomia (UMI 3386: CNRS U de Chile / PUC / U Conception), Santiago, Chile 6 Department of Astronomy, University of Maryland, College Park, MD 230742, USA 7 Dep. de F´ısica Te´orica, Fac. de Ciencias, UAM Campus Cantoblanco, 28049 Madrid, Spain 8 Astrophysikalisches Institut und Universit¨atssternwarte, Friedrich-Schiller-Universit¨at Jena, Schillergachen 23, 07745 Jena, Germany 9 Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978, USA 10 ALMA, Avda Apoquindo 3846, Piso 19, Edicio Alsacia, Las Condes, Santiago, Chile E-mail contact: riviere at astro.rug.nl Context. Debris discs are thought to be formed through the collisional grinding of planetesimals, and can be considered as the outcome of planet formation. Understanding the properties of gas and dust in debris discs can help us to comprehend the architecture of extrasolar planetary systems. Herschel Space Observatory far-infrared (IR) photometry and spectroscopy have provided a valuable dataset for the study of debris discs gas and dust composition. This paper is part of a series of papers devoted to the study of Herschel PACS observations of young stellar associations. Aims. This work aims at studying the properties of discs in the Beta Pictoris Moving Group (BPMG) through far-IR PACS observations of dust and gas. Methods. We obtained Herschel-PACS far-IR photometric observations at 70, 100 and 160 µm of 19 BPMG members, together with spectroscopic observations of four of them. Spectroscopic observations were centred at 63.18 µm and 157 µm, aiming to detect [OI] and [CII] emission. We incorporated the new far-IR observations in the SED of BPMG members and fitted modified blackbody models to better characterise the dust content. Results. We have detected far-IR excess emission toward nine BPMG members, including the first detection of an IR excess toward HD 29391.The star HD 172555, shows [OI] emission, while HD 181296, shows [CII] emission, expanding the short list of debris discs with a gas detection. No debris disc in BPMG is detected in both [OI] and [CII]. The −5 discs show dust temperatures in the range 55 to 264 K, with low dust masses (6.6 × 10 M⊕ to 0.2 M⊕) and radii from blackbody models in the range 3 to 82 AU. All the objects with a gas detection are early spectral type stars with a hot dust component. Accepted by A&A http://arxiv.org/pdf/1404.1815

A Dusty M5 Binary in the beta Pictoris Moving Group David R. Rodriguez1, B. Zuckerman2, Jacqueline K. Faherty3,4, and Laura Vican2 1 Departamento de Astronom´ıa, Universidad de Chile, Casilla 36-D, Santiago, Chile 2 Dept. of Physics & Astronomy, University of California, Los Angeles 90095, USA 3 Dept. of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road NW, Washington, DC 20015, USA 4 Hubble Fellow E-mail contact: drodrigu at das.uchile.cl We report the identification of a new wide separation binary (LDS 5606) in the ∼20 Myr-old beta Pic moving group. This M5+M5 pair has a projected separation of 26′′, or ∼1700 AU at a distance of 65 pc. Both stars host warm circumstellar disks and many strong and emission lines. Spectroscopic observations reveal signatures of youth for both stars and on-going mass accretion in the primary. The properties of LDS 5606 make it an older analog to the ∼8 Myr TWA 30 system, which is also composed of a pair of widely separated mid-M dwarfs, each hosting their own warm circumstellar disks. LDS 5606 joins a rather exclusive club of only 3 other known stellar systems where both members of a binary, far from any molecular cloud, are orbited by detected circumstellar disks. Accepted by A&A http://arxiv.org/pdf/1404.2543

Protoplanetary disc evolution affected by star-disc interactions in young stellar clusters Giovanni P. Rosotti1,2,3, James E. Dale2,3, Maria de Juan Ovelar4, David A. Hubber2,3, J.M. Diederik Kruijssen5, Barbara Ercolano2,3, and Stefanie Walch5 1 Max-Planck-Institut f¨ur extraterrestrische Physik, Giessenbachstraße, D-85748 Garching, Germany

31 2 Excellence Cluster Universe, Boltzmannstr. 2, D-85748 Garching, Germany 3 Universitats-Sternwarte M¨unchen, Scheinerstraße 1, D-81679 M¨unchen, Germany 4 Leiden Observatory, Leiden University, P.O. Box 9513, 2300RA Leiden, The Netherlands 5 Max-Planck-Institut f¨ur Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching, Germany E-mail contact: rosotti at usm.lmu.de Most stars form in a clustered environment. Therefore, it is important to assess how this environment influences the evolution of protoplanetary discs around young stars. In turn, this affects their ability to produce planets and ultimately life. We present here for the first time 3D SPH/N-body simulations that include both the hydrodynamical evolution of the discs around their natal stars, as well as the dynamics of the stars themselves. The discs are viscously evolving, accreting mass onto the central star and spreading. We find penetrating encounters to be very destructive for the discs as in previous studies, although the frequency of such encounters is low. We also find, however, that encounter influence the disc radii more strongly than other disc properties such as the disc mass. The disc sizes are set by the competition between viscous spreading and the disruptive effect of encounters. As discs spread, encounters become more and more important. In the regime of rapid spreading encounters simply truncate the discs, stripping the outer portions. In the opposite regime, we find that the effect of many distant encounters is able to limit the disc size. Finally, we predict from our simulations that disc sizes are limited by encounters at stellar densities exceeding ∼ 2–3 × 103 pc−2. Accepted by MNRAS http://arxiv.org/pdf/1404.1931

Class 0 Protostars in the Perseus Molecular Cloud: A Correlation Between the Youngest Protostars and the Dense Gas Distribution S.I. Sadavoy1,2,3, J. Di Francesco1,2, Ph. Andre4, S. Pezzuto5, J.-P. Bernard6,7, A. Maury4, A. Men’shchikov4, F. Motte4, Q. Nguyen-Luong8, N. Schneider9, D. Arzoumanian10, M. Benedettini5, S. Bontemps9,11, D. Elia5, M. Hennemann4, T. Hill12, V. Konyves4,10, F. Louvet4, N. Peretto13, A. Roy4 and G. J. White14,15 1 Department of Physics & Astronomy, University of Victoria, PO Box 355, STN CSC, Victoria, BC, V8W 3P6, Canada 2 National Research Council Canada, 5071 West Saanich Road, Victoria, BC, V9E 2E7, Canada 3 Current address: Max-Planck-Institut fur Astronomie, Konigstuhl 17, 69117 Heidelberg, Germany 4 Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service d’Astrophysique, Saclay, 91191 Gif- sur-Yvette, France 5 Istituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, 00133, Rome, Italy 6 CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France 7 Universite de Toulouse, UPS-OMP, IRAP, 31028 Toulouse Cedex 4, France 8 Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON, M5S 3H8, Canada 9 Universite de Bordeaux, LAB, UMR 5804, F-33270, Floirac, France 10 IAS, CNRS (UMR 8617), Universite Paris-Sud 11, Batiment 121, 91400 Orsay, France 11 CNRS, LAB, UMR 5804, F-33270, Floirac, France 12 Joint ALMA Observatory, Alonso de Cordova 3107, Vitacura 763-0355, Santiago, Chile 13 School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA, UK 14 Department of Physics and Astronomy, The Open University, Milton Keynes, MK7 6AA, UK 15 The Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, UK E-mail contact: sadavoy at mpia.de We use PACS and SPIRE continuum data at 160 um, 250 um, 350 um, and 500 um from the Herschel Survey to sample seven clumps in Perseus: B1, B1-E, B5, IC348, L1448, L1455, and NGC1333. Additionally, we identify and characterize the embedded Class 0 protostars using detections of compact Herschel sources at 70 um as well as archival Spitzer catalogues and SCUBA 850 um photometric data. We identify 28 candidate Class 0 protostars, four of which are newly discovered sources not identified with Spitzer. We find that the star formation efficiency of clumps, as traced by Class 0 protostars, correlates strongly with the flatness of their respective column density distributions at high values. This correlation suggests that the fraction of high column density material in a clump reflects only its youngest protostellar population rather than its entire source population. We propose that feedback from either the

32 formation or evolution of protostars changes the local density structure of clumps. Accepted by ApJL http://arxiv.org/pdf/1404.7142

Orbital Motion in Pre-Main Sequence Binaries G. H. Schaefer1, L. Prato2, M. Simon3 and J. Patience4 1 The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023, USA 2 Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA 3 Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794, USA 4 Astrophysics Group, School of Physics, University of Exeter, Exeter, EX4 4QL, UK; School of Earth and , Arizona State University, PO Box 871404, Tempe, Arizona, 85287, USA E-mail contact: schaefer at chara-array.org We present results from our ongoing program to map the visual orbits of pre-main sequence binaries in the Taurus star forming region using adaptive optics imaging at the Keck Observatory. We combine our results with measurements reported in the literature to analyze the orbital motion for each binary. We present preliminary orbits for DF Tau, T Tau S, ZZ Tau, and the Pleiades binary HBC 351. Seven additional binaries show curvature in their relative motion. Currently, we can place lower limits on the orbital periods for these systems; full solutions will be possible with more orbital coverage. Five other binaries show motion that is indistinguishable from linear motion. We suspect that these systems are bound and might show curvature with additional measurements in the future. The observations reported herein lay critical groundwork toward the goal of measuring precise masses for low-mass pre-main sequence stars. Accepted by Astronomical Journal http://arxiv.org/pdf/1405.0225

First spectroscopic observations of the sub-stellar companion of the young debris disk star PZ Telescopii T.O.B. Schmidt1, M. Mugrauer1, R. Neuh¨auser1, N. Vogt2, S. Witte3, P.H. Hauschildt3, Ch. Helling4, and A. Seifahrt5 1 Astrophysikalisches Institut und Universit¨ats-Sternwarte, Universit¨at Jena, Schillerg¨aßchen 2-3, 07745 Jena, Ger- many 2 Departamento de F´ısica y Astronom´ıa, Universidad de Valpara´ıso, Avenida Gran Breta˜na 1111, Valpara´ıso, Chile 3 Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany 4 SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS, UK 5 Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave., IL 60637, USA E-mail contact: tobi at astro.uni-jena.de In 2010 a sub-stellar companion to the pre-main sequence star PZ Tel and member of the about 12 Myr old β Pic moving group was found by high-contrast direct imaging independently by two teams. In order to determine the basic parameters of this companion more precisely and independent of evolutionary models, hence age independent, we obtained follow-up spectroscopic observations of primary and companion. We use the Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) at the Very Large Telescope Unit 4/YEPUN of ESO’s Paranal Observatory in H+K band and process the data using the spectral deconvolution technique. The resulting spectrum of the companion is then compared to a grid of Drift-Phoenix synthetic model spectra, a combination of a general-purpose model atmosphere code with a non-equilibrium, stationary cloud and dust model, using a χ2 minimization analysis. We find a best fitting spectral type of G6.5 for PZ Tel A. The extracted spectrum of the sub-stellar companion, at a +138 spatial position compatible with earlier orbit estimates, yields a temperature Teff = 2500−115 K, a visual extinction +0.84 +0.51 AV =0.53−0.53 mag, a of log g =3.50−0.30 dex, and a at the edge of the grid of [M/H] = +0.06 +0.28 0.30−0.30 dex. We derive a luminosity of log(Lbol/L⊙) = −2.66−0.08, a radius of R = 2.42−0.34 RJup and a mass of +16.9 M =7.5−4.3 MJup for the PZ Tel companion, being consistent with most earlier estimates using photometry alone. Combining our results with evolutionary models, we find a best fitting mass of about 21 masses at an age

33 +4 corresponding to the recently determined lithium depletion age of 7−2 Myr. Hence, the PZ Tel companion is most +8 likely a wide companion in the 12−4 Myr old β Pic moving group. Accepted by A&A http://arxiv.org/pdf/1404.2870

Dancing with the Stars: Formation of the triple system and its effect on the debris disks Andrew Shannon1, Cathie Clarke1, and Mark Wyatt1 1 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, United Kingdom of Great Britain and Northern Ireland, CB3 0HA E-mail contact: shannon at ast.cam.ac.uk Fomalhaut is a triple system, with all components widely separated (∼105 AU). Such widely separated binaries are thought to form during cluster dissolution, but that process is unlikely to form such a triple system. We explore an alternative scenario, where A and C form as a tighter binary from a single molecular cloud core (with semimajor axis ∼104 AU), and B is captured during cluster dispersal. We use N-body simulations augmented with the Galactic tidal forces to show that such a system naturally evolves into a Fomalhaut-like system in about half of cases, on a timescale compatible with the age of Fomalhaut. From initial non-interacting orbits, Galactic tides drive cycles in B’s eccentricity that lead to a close encounter with C. After several close encounters, typically lasting tens of millions of years, one of the stars is ejected. The Fomalhaut-like case with both components at large separations is almost invariably a precursor to the ejection of one component, most commonly Fomalhaut C. By including circumstellar debris in a subset of the simulations, we also show that such an evolution usually does not disrupt the coherently eccentric debris disk around Fomalhaut A, and in some cases can even produce such a disk. We also find that the final eccentricity of the disk around A and the disk around C are correlated, which may indicate that the dynamics of the three stars stirred C’s disk, explaining its unusual brightness. Accepted by MNRAS http://arxiv.org/pdf/1404.7136

Chandra Resolves the T Tauri RW Aur Stephen L. Skinner1 and Manuel G¨udel2 1 CASA, Univ. of Colorado, Boulder, CO, USA 80309-0389 2 Dept. of Astrophysics, Univ. of Vienna, T¨urkenschanzstr. 17, A-1180 Vienna, Austria E-mail contact: stephen.skinner at colorado.edu RW Aur is a multiple T Tauri system consisting of an early-K type primary (A) and a K5 companion (B) at a separation of 1′′. 4. RW Aur A drives a bipolar optical jet that is well-characterized optically. We present results of a sensitive Chandra observation whose primary objective was to search for evidence of soft extended X-ray emission along the jet, as has been seen for a few other nearby T Tauri stars. The binary is clearly resolved by Chandra and both stars are detected as X-ray sources. The X-ray spectra of both stars reveal evidence for cool and hot plasma. Suprisingly, the X-ray luminosity of the less-massive secondary is at least twice that of the primary and is variable. The disparity is attributed to the primary whose X-ray luminosity is at the low end of the range for classical T Tauri stars of similar mass based on established correlations. Deconvolved soft-band images show evidence for slight outward elongation of the source structure of RW Aur A along the blueshifted jet axis inside the central arcsecond. In addition, a faint X-ray emission peak is present on the redshifted axis at an offset of 1′′. 2±0′′. 2 arcsec from the star. Deprojected jet speeds determined from previous optical studies are too low to explain this faint emission peak as shock-heated jet plasma. Thus, unless flow speeds in the redshifted jet have been underestimated, other mechanisms such as magnetic jet heating may be involved. Accepted by ApJ http://arxiv.org/pdf/1404.2631

34 A Test of Star Formation Laws in Disk Galaxies. II. Dependence on dynamical proper- ties Chutipong Suwannajak1, Jonathan C. Tan1 and Adam K. Leroy2 1 University of Florida, USA 2 NRAO, Charlottesville, USA E-mail contact: jt at astro.ufl.edu

We use the observed radial profiles of the mass surface densities of total, Σg, and molecular, ΣH2, gas, rotation velocity and star formation rate (SFR) surface density, Σsfr, of the molecular-rich (ΣH2 ≥ ΣHI/2) regions of 16 nearby disk 1.5 galaxies to test several star formation laws: a ”Kennicutt-Schmidt” law, Σsfr = AgΣg,2; a ”Constant Molecular” law, Σsfr = AH2ΣH2,2; the turbulence-regulated laws of Krumholz & McKee (KM05) and Krumholz, McKee & Tumlinson (KMT09), a ”Gas-Ω” law, Σsfr = BΩΣgΩ; and a shear-driven ”GMC Collision” law, Σsfr = BCCΣgΩ(1 − 0.7β), where β ≡ d ln vcirc/d ln r. If allowed one free normalization parameter for each galaxy, these laws predict the SFR with rms errors of factors of 1.4 to 1.8. If a single normalization parameter is used by each law for the entire galaxy sample, then rms errors range from factors of 1.5 to 2.1. Although the Constant Molecular law gives the smallest rms errors, the improvement over the KMT, Kennicutt-Schmidt and GMC Collision laws is not especially significant, particularly given the different observational inputs that the laws utilize and the scope of included physics, which ranges from empirical relations to detailed treatment of interstellar medium processes. We next search for systematic variation of star formation law parameters with local and global galactic dynamical properties of disk shear rate (related to β), rotation speed and presence of a bar. We demonstrate with high significance that higher shear rates enhance star formation efficiency per local orbital time. Such a trend is expected if GMC collisions play an important role in star formation, while an opposite trend would be expected if development of disk gravitational instabilities is the controlling physics. Accepted by Astrophysical Journal http://arxiv.org/pdf/1404.1359

A very young, compact bipolar H2O maser outflow in the intermediate-mass star- forming LkHα 234 region J.M. Torrelles1, S. Curiel2, R. Estalella3, G. Anglada4, J.F. G´omez4, J. Cant´o2, N.A. Patel5, M.A. Trinidad6, J.M. Girart7, C. Carrasco-Gonz´alez8, L.F. Rodr´ıguez8 1 Institut de Ci´encies de l’Espai (CSIC-IEEC) and Institut de Ci´encies del Cosmos (UB-IEEC), Mart´ıi Franqu´es 1, 08028 Barcelona, Spain 2 Instituto de Astronom´ıa(UNAM), Apartado 70-264, 04510 M´exico D. F., M´exico 3 Departament d’Astronomia i Meteorologia and Institut de Ci´encies del Cosmos (IEEC-UB), Universitat de Barcelona, Mart´ıi Franqu´es 1, 08028 Barcelona, Spain 4 Instituto de Astrof´ısica de Andaluc´ıa(CSIC), Apartado 3004, 18080 Granada, Spain 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 6 Departamento de Astronom´ıa, Universidad de Guanajuato, Apdo. Postal 144, 36000 Guanajuato, M´exico 7 Institut de Ci´encies de l’Espai (CSIC-IEEC), Campus UAB, Facultat de Ci´encies, C5p 2, 08193 Bellaterra, Spain 8 Centro de Radioastronom´ıay Astrof´ısica (UNAM), 58089 Morelia, M´exico E-mail contact: torrelles at ieec.cat

We report multi- VLBI H2O maser observations towards the compact cluster of YSOs close to the Herbig LkHα 234. This cluster includes LkHα 234 and at least nine more YSOs that are formed within projected distances of ′′ ∼10 (∼9,000 AU). We detect H2O maser emission towards four of these YSOs. In particular, our VLBI observations ′′ (including measurements) reveal a remarkable very compact (∼0.2 ≃ 180 AU), bipolar H2O maser outflow emerging from the embedded YSO VLA 2. We estimate a kinematic age of ∼40 yr for this bipolar outflow, −1 −4 −3 −1 −1 with expanding velocities of ∼20 km s and momentum rate M˙ wVw ≃ 10 –10 M⊙ yr km s × (Ω/4π), powered by a YSO of a few solar masses. We propose that the outflow is produced by recurrent episodic jet ejections associated with the formation of this YSO. Short-lived episodic ejection events have previously been found towards high-mass YSOs. We show now that this behaviour is also present in intermediate-mass YSOs. These short-lived episodic ejections are probably related to episodic increases in the accretion rate, as observed in low-mass YSOs. We

35 predict the presence of an accretion disk associated with VLA 2. If detected, this would represent one of the few known examples of intermediate-mass stars with a disk-YSO-jet system at scales of a few hundred AU. Accepted by MNRAS http://arxiv.org/pdf/1404.7273

Near-infrared emission from sublimating dust in collisionally active debris disks R. van Lieshout1, C. Dominik1,2, M. Kama3,1 and M. Min1 1 Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands 2 Department of Astrophysics/IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Nether- lands 3 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands E-mail contact: r.vanlieshout at uva.nl Hot exozodiacal dust is thought to be responsible for excess near-infrared (NIR) emission emanating from the innermost parts of some debris disks. The origin of this dust, however, is still a matter of debate. We test whether hot exozodiacal dust can be supplied from an exterior parent belt by Poynting–Robertson (P–R) drag, paying special attention to the pile-up of dust that occurs due to the interplay of P–R drag and dust sublimation. Specifically, we investigate whether pile-ups still occur when collisions are taken into account, and if they can explain the observed NIR excess. We computed the steady-state distribution of dust in the inner disk by solving the continuity equation. First, we derived an analytical solution under a number of simplifying assumptions. Second, we developed a numerical debris disk model that for the first time treats the complex interaction of collisions, P–R drag, and sublimation in a self- consistent way. From the resulting dust distributions, we generated thermal emission spectra and compare these to observed excess NIR fluxes. We confirm that P–R drag always supplies a small amount of dust to the sublimation zone, but find that a fully consistent treatment yields a maximum amount of dust that is about 7 times lower than that given by analytical estimates. The NIR excess due to this material is much less (<10−3 for A-type stars with parent belts at >1 AU) than the values derived from interferometric observations (∼10−2). Pile-up of dust still occurs when collisions are considered, but its effect on the NIR flux is insignificant. Finally, the cross-section in the innermost regions is clearly dominated by barely bound grains. Accepted by A&A http://arxiv.org/pdf/1404.3271

Stellar magnetism: empirical trends with age and rotation A. A. Vidotto1,2, S. G. Gregory1, M. Jardine1, J.-F. Donati3, P. Petit3, J. Morin4, C. P. Folsom3, J. Bouvier5, A. C. Cameron1, G. Hussain6, S. Marsden7, I. A Waite7, R. Fares1, S. Jeffers8 and J. D. do Nascimento Jr9 1 SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK 2 Observatoire de Gen`eve, Universit´ede Gen`eve, Chemin des Mailletes 51, Versoix, 1290, Switzerland 3 LATT - CNRS/Universit´ede Toulouse, 14 Av. E. Belin, Toulouse, F-31400, France 4 LUPM-UMR5299, CNRS & Universit´eMontpellier II, Place E. Bataillon, Montpellier, F-34095, France 5 UJF-Grenoble 1/CNRS-INSU, Inst. de Plan´etologie et d’Astrophysique de Grenoble, Grenoble, F-38041, France 6 ESO, Karl-Schwarzschild-Strasse 2, D-85748, Garching bei M¨nchen, Germany 7 Computational Engineering and Science Research Centre, University of Southern Queensland, Toowoomba, 4350, Australia 8 Institut f¨ur Astrophysik, Georg-August-Universit¨at, Friedrich-Hund-Platz 1, D-37077, Goettingen, Germany 9 Dep. de Fisica Te´orica e Exp., Un. Federal do Rio Grande do Norte, CEP: 59072-970 Natal, RN, Brazil E-mail contact: aline.vidotto at unige.ch

We investigate how the observed large-scale surface magnetic fields of low-mass stars (∼0.1-2 M⊙), reconstructed

36 through Zeeman-Doppler imaging (ZDI), vary with age t, rotation period Prot, Rossby number Ro and X-ray emission. Our sample consists of 104 magnetic maps of 73 stars, from accreting pre-main sequence to main-sequence objects, spanning ages from ∼ 1 Myr to ∼ 10 Gyr. For non-accreting dwarfs we empirically find that the unsigned average −0.655±0.045 large-scale surface magnetic field h|BV |i is related to age as t . This relation has a similar power dependency to that identified in the seminal work of Skumanich (1972), which has served as the basis of gyrochronology, whereby stellar ages can be derived from rotation measurements. Our relation could therefore be used as an alternative method −1.32±0.14 −1.38±0.14 to estimate the age of stars (“magnetochronology”). We also find that h|BV |i ∝ Prot and h|BV |i ∝ Ro , supporting the presence of a linear-type dynamo of the large-scale field. The trends we find for large-scale stellar magnetism from ZDI studies are consistent with the trends found from Zeeman broadening measurements, which are sensitive to the unsigned large- and small-scale magnetic field h|BI |i. These similarities indicate that the fields recovered from both techniques are coupled to each other, suggesting that small- and large-scale fields could share the same dynamo field generation processes. We also investigate how the small- and large-scale structures contribute to X-ray emission. These contributions have similar slopes within 3σ, but samples with large dynamic range of h|BI |i are required to better constrain this result. For the accreting objects, fewer statistically significant relations are found, with one being a correlation between the unsigned magnetic flux ΦV and Prot, which we attribute to a signature of star-disc interaction, rather than being driven by the dynamo magnetic field generation process. Accepted by MNRAS http://arxiv.org/pdf/1404.2733

Complex organic molecules in protoplanetary disks Catherine Walsh1, T. J. Millar2, Hideko Nomura3,4,5, Eric Herbst6,7, Susanna Widicus Weaver8, Yuri Aikawa9, Jacob C. Laas8 and Anton I. Vasyunin10,11 1 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA, Leiden, The Netherlands 2 Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, University Road, Belfast, BT7 1NN, UK 3 Department of Astronomy, Graduate School of Science, Kyoto University, 606-8502, Kyoto, Japan 4 National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo, 181-8588, Japan 5 Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, 152- 8551, Tokyo, Japan 6 Departments of Physics, Chemistry and Astronomy, The Ohio State University, Columbus, OH, 43210, USA 7 Departments of Chemistry, Astronomy, and Physics, University of Virginia, Charlottesville, VA, 22904, USA 8 Department of Chemistry, Emory University, Atlanta, GA, 30322, USA 9 Department of Earth and Planetary Sciences, Kobe University, 1-1 Rokkodai-cho, Nada, 657-8501, Kobe, Japan 10 Department of Chemistry, Emory University, Atlanta, GA, 30322, USA 11 Visiting Scientist, Ural Federal University, 620075, Ekaterinburg, Russia E-mail contact: cwalsh at strw.leidenuniv.nl Context: Protoplanetary disks are vital objects in star and planet formation, possessing all the material, gas and dust, which may form a planetary system orbiting the new star. Small, simple molecules have traditionally been detected in protoplanetary disks; however, in the ALMA era, we expect the molecular inventory of protoplanetary disks to significantly increase. Aims: We investigate the synthesis of complex organic molecules (COMs) in protoplanetary disks to put constraints on the achievable chemical complexity and to predict species and transitions which may be observable with ALMA. Methods: We have coupled a 2D steady-state physical model of a protoplanetary disk around a typical T Tauri star with a large gas-grain chemical network including COMs. We compare the resulting column densities with those derived from observations and perform ray-tracing calculations to predict line spectra. We compare the synthesised line intensities with current observations and determine those COMs which may be observable in nearby objects. We also compare the predicted grain-surface abundances with those derived from cometary comae observations. Results: We find COMs are efficiently formed in the disk midplane via grain-surface chemical reactions, reaching peak grain-surface fractional abundances ∼ 10−6-10−4 that of the H nuclei number density. COMs formed on grain surfaces are returned to the gas phase via non-thermal desorption; however, gas-phase species reach lower fractional abundances than their grain-surface equivalents, ∼ 10−12-10−7. Including the irradiation of grain mantle material

37 helps build further complexity in the ice through the replenishment of grain-surface radicals which take part in further grain-surface reactions. There is reasonable agreement with several line transitions of H2CO observed towards T Tauri star-disk systems. There is poor agreement with HC3N lines observed towards LkCa 15 and GO Tau and we discuss possible explanations for these discrepancies. The synthesised line intensities for CH3OH are consistent with upper limits determined towards all sources. Our models suggest CH3OH should be readily observable in nearby protoplanetary disks with ALMA; however, detection of more complex species may prove challenging, even with ALMA ”Full Science” capabilities. Our grain-surface abundances are consistent with those derived from cometary comae observations providing additional evidence for the hypothesis that comets (and other planetesimals) formed via the coagulation of icy grains in the Sun’s natal disk. Accepted by Astronomy and Astrophysics http://adsabs.harvard.edu/pdf/2014A%26A...563A..33W

ESO-Ha 574 and Par-Lup3-4 jets: Exploring the spectral, kinematical and physical properties E.T. Whelan1, R. Bonito2,3, S. Antoniucci4, J.M. Alcal´a5, T. Giannini4, B. Nisini4, F. Bacciotti6, L. Podio6,7, B. Stelzer3 and F. Comer´on8 1 Institut f¨ur Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Eberhard Karls Universit¨at, 72076 T¨ubingen, Germany 2 Universit`adi Palermo, P.zza del Parlamento 1, 90134 Palermo, Italy 3 INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy 4 INAF - Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio, Italy 5 INAF - Osservatorio Astronomico di Capodimonte, via Moiariello, 16, 80131 Napoli, Italy 6 INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy 7 UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, 38041 Grenoble, France 8 ESO, Alonso de Crdova 3107, Castilla 19001, Santiago 19, Chile E-mail contact: emma.whelan at astro.uni-tuebingen.de In this paper a comprehensive analysis of VLT/X-Shooter observations of two jet systems, namely ESO-Hα 574 a K8 classical T Tauri star and Par-Lup 3-4 a very low mass (0.13 M⊙) M5 star, is presented. Both stars are known to have near-edge on accretion disks. A summary of these first X-shooter observations of jets was given in a 2011 letter. The new results outlined here include flux tables of identified emission lines, information on the morphology, kinematics and physical conditions of both jets and, updated estimates of M˙ out / M˙ acc. Asymmetries in the ESO-Hα 574 flow are investigated while the Par-Lup 3-4 jet is much more symmetric. The density, temperature, and therefore origin of the gas traced by the Balmer lines are investigated from the Balmer decrements and results suggest an origin in a jet for ESO-Hα 574 while for Par-Lup 3-4 the temperature and density are consistent with an accretion flow. M˙ acc is estimated from the luminosity of various accretion tracers. For both targets, new luminosity relationships and a re-evaluation of the effect of reddening and grey extinction (due to the edge-on disks) allows for substantial improvements on previous −1 −1 estimates of M˙ acc. It is found that log(M˙ acc) = -9.15 ± 0.45 M⊙yr and -9.30 ± 0.27 M⊙yr for ESO-Hα 574 and Par-Lup 3-4, respectively. Additionally, the physical conditions in the jets (electron density, electron temperature, and ionisation) are probed using various line ratios and compared with previous determinations from iron lines. The results are combined with the luminosity of the [SII]λ6731 line to derive M˙ out through a calculation of the gas emissivity based on a 5-level atom model. As this method for deriving M˙ out comes from an exact calculation based on the jet parameters (measured directly from the spectra) rather than as was done previously from an approximate formula based on the value of the critical density at an assumed unknown temperature, values of M˙ out are far more accurate. Overall the accuracy of earlier measurements of M˙ out / M˙ acc is refined and M˙ out / M˙ acc = 0.5 (+1.0)(-0.2) and 0.3 (+0.6)(-0.1) for the ESO-Hα 574 red and blue jets, respectively, and 0.05 (+0.10)(-0.02) for both the Par-Lup 3-4 red and blue jets. While the value for the total (two-sided) M˙ out / M˙ acc in ESO-Hα 574 lies outside the range predicted by magneto-centrifugal jet launching models, the errors are large and the effects of veiling and scattering on extinction measurements, and therefore the estimate of M˙ acc, should also be considered. ESO-Hα 574 is an excellent case study for understanding the impact of an edge-on accretion disk on the observed stellar emission. The improvements in the derivation of M˙ out / M˙ acc means that this ratio for Par-Lup 3-4 now lies within the range predicted by leading models,

38 as compared to earlier measurements for very low mass stars. Par-Lup 3-4 is one of a small number of brown dwarfs and very low mass stars which launch jets. Therefore, this result is important in the context of understanding how M˙ out / M˙ acc and, thus, jet launching mechanisms for the lowest mass jet driving sources, compare to the case of the well-studied low mass stars. Accepted by Astronomy and Astrophysics http://arxiv.org/pdf/1403.3232

Multi-epoch Sub-arcsecond [Fe II] Spectroimaging of the DG Tau Outflows with NIFS. I. First data epoch Marc C White1, Peter J McGregor1, Geoffrey V Bicknell1, Raquel Salmeron1 and Tracy L Beck2 1 Research School of Astronomy & Astrophysics, The Australian National University, Cotter Rd., Weston, ACT, 2611, Australia 2 Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD, 21218, USA E-mail contact: marc.white at anu.edu.au Investigating the outflows emanating from young stellar objects (YSOs) on sub-arcsecond scales provides important clues to the nature of the underlying accretion-ejection process occurring near the central protostar. We have investi- gated the structures and kinematics of the outflows driven by the YSO DG Tauri, using the Near-infrared Integral Field Spectrograph (NIFS) on North. The blueshifted outflow shows two distinct components in [Fe II] 1.644 µm emission, which are separated using multi-component line fitting. Jet parameters are calculated for the high-velocity component. A stationary recollimation shock is observed, in agreement with previous X-ray and FUV observations. The presence of this shock indicates that the innermost streamlines of the high-velocity component are launched at a very small radius, 0.01–0.15 AU, from the central star. The jet accelerates and expands downstream of the recol- limation shock; the ‘acceleration’ is likely a sign of velocity variations in the jet. No evidence of rotation is found, and we compare this non-detection to previous counter-claims. Moving jet knots, likely the result of the jet velocity variations, are observed. One of these knots moves more slowly than previously observed knots, and the knot ejection interval appears to be non-periodic. An intermediate-velocity component surrounds this central jet, and is interpreted as the result of a turbulent mixing layer along the jet boundaries generated by lateral entrainment of material by the high-velocity jet. Lateral entrainment requires the presence of a magnetic field of strength a few mG or less at hundreds of AU above the disc surface, which is argued to be a reasonable proposition. In H2 1-0 S(1) 2.1218 µm emission, a wide-angle, intermediate-velocity blueshifted outflow is observed. Both outflows are consistent with being launched by a magnetocentrifugal disc wind, although an X-wind origin for the high-velocity jet cannot be ruled out. The redshifted outflow of DG Tau takes on a bubble-shaped morphology, which will be discussed in a future paper. Accepted by MNRAS http://arxiv.org/pdf/1404.0728

Multi-epoch Sub-arcsecond [Fe II] Spectroimaging of the DG Tau Outflows with NIFS. II. On the Nature of the Bipolar Outflow Asymmetry Marc C White1, Geoffrey V Bicknell1, Peter J McGregor1 and Raquel Salmeron1 1 Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT, 2611, Australia E-mail contact: marc.white at anu.edu.au The origin of bipolar outflow asymmetry in young stellar objects (YSOs) remains poorly understood. It may be due to an intrinsically asymmetric outflow launch mechanism, or it may be caused by the effects of the ambient medium surrounding the YSO. Answering this question is an important step in understanding outflow launching. We have investigated the bipolar outflows driven by the T Tauri star DG Tauri on scales of hundreds of AU, using the Near-infrared Integral Field Spectrograph (NIFS) on Gemini North. The approaching outflow consists of a well- collimated jet, nested within a lower-velocity disc wind. The receding outflow is composed of a single-component bubble-like structure. We analyse the kinematics of the receding outflow using kinetic models, and determine that it is a quasi-stationary bubble with an expanding internal velocity field. We propose that this bubble forms because the receding counterjet from DG Tau is obstructed by a clumpy ambient medium above the surface,

39 based on similarities between this structure and those found in the modelling of active galactic nuclei outflows. We find evidence of interaction between the obscured counterjet and clumpy ambient material, which we attribute to the large molecular envelope around the DG Tau system. An analytical model of a momentum-driven bubble is shown to be consistent with our interpretation. We conclude that the bipolar outflow from DG Tau is intrinsically symmetric, and the observed asymmetries are due to environmental effects. This mechanism can potentially be used to explain the observed bipolar asymmetries in other YSO outflows. Accepted by MNRAS http://arxiv.org/pdf/1404.6002

A Parametric Modeling Approach to Measuring the Gas Masses of Circumstellar Disks Jonathan P. Williams1 and William M. J. Best1 1 Institute for Astronomy, University of Hawaii, Honolulu, USA E-mail contact: jpw at ifa.hawaii.edu The disks that surround young stars are mostly composed of molecular gas, which is harder to detect and interpret than the accompanying dust. Disk mass measurements have therefore relied on large and uncertain extrapolations from the dust to the gas. We have developed a grid of models to study the dependencies of isotopologue CO line strengths on disk structure and temperature parameters and find that a combination of 13CO and C18O observations provides a robust measure of the gas mass. We apply this technique to Submillimeter Array observations of nine circumstellar disks and published measurements of six well studied disks. We find evidence for selective photodissociation of C18O and determine masses to within a factor of about three. The inferred masses for the nine disks in our survey range from 0.7 − 6 MJup, and all are well below the extrapolation from the interstellar medium gas-to-dust ratio of 100. This is consistent with the low masses of planets found around such stars, and may be due to accretion or photoevaporation of a dust-poor upper atmosphere. However, the masses may be underestimated if there are more efficient CO depletion pathways than those known in molecular clouds and cold cores. Accepted by Astrophysical Journal http://arxiv.org/pdf/1312.0151

A spider-like outflow in Barnard 5 - IRS 1: The transition from a collimated jet to a wide-angle outflow? Luis A. Zapata1, H´ector G. Arce2, Erin Brasseld3, Aina Palau4, Nimesh Patel3, and Jaime E. Pineda5 1 Centro de Radioastronom´ıay Astros´ıca, UNAM campus Morelia, M´exico 2 Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06511, USA 3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA 4 Institut de Ci´encies de l’Espai (CSIC-IEEC), Campus UAB-Facultat de Ci´encies, Torre C5-parell 2, E-08193 Bel- laterra, Catalunya, Spain 5 Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland E-mail contact: lzapata at crya.unam.mx We present line and continuum observations made with the Submillimeter Array (SMA) of the young stellar object Barnard 5 - IRS1 located in the Perseus molecular cloud. Our 12CO (2–1) line observations resolve the high-velocity bipolar northeast-southwest outflow associated with this source. We find that the outflowing gas shows different structures at three different velocity regimes, in both lobes, resulting in a spider-like morphology. In addition to the low-velocity, cone-like (wide-angle) lobes that have previously been observed, we report the presence of intermediate- velocity parabolic shells emerging very close to the Class I protostar, as well as high velocity molecular bullets that appear to be associated to the optical/IR jet emanating from this source. These compact high-velocity features reach radial velocities of about 50 km s−1 away from the cloud velocity. We interpret the peculiar spider-like morphology is a result of the molecular material being entrained by a wind with both a collimated jet-like component and a wide-angle component. We suggest the outflow is in a transitional evolutionary phase between a mostly jet-driven flow and an outflow in which the entrainment is dominated by the wide-angle wind component. We also detect 1300 µm continuum emission at the position of the protostar, which likely arises from the dusty envelope and disk surrounding

40 13 the protostar. Finally, we report the detection of CO (2–1) and SO (65–54) emission arising from the outflow and the location of the young stellar object. Accepted by MNRAS http://arxiv.org/pdf/1404.6147

Radiation Transfer of Models of Massive Star Formation. III. The Evolutionary Se- quence Yichen Zhang1, Jonathan Tan2 and Takashi Hosokawa3 1 Department of Astronomy, Yale University, New Haven, CT 06520, USA 2 Departments of Astronomy & Physics, University of Florida, Gainesville, FL 32611, USA 3 Department of Physics, University of Tokyo, Tokyo 113-0033, Japan E-mail contact: yczhang.astro at gmail.com We present radiation transfer simulations of evolutionary sequences of massive protostars forming from massive dense cores in environments of high mass surface densities, based on the Turbulent Core model (McKee & Tan 2003). The protostellar evolution is calculated with a multi-zone numerical model, with accretion rate regulated by feedback from an evolving disk-wind outflow cavity. Disk evolution is calculated assuming a fixed ratio of disk to protostellar mass, while core envelope evolution assumes inside-out collapse of the core of fixed outer radius. In this framework, an evolutionary track is determined by three environmental initial conditions: core mass Mc, mass surface density of the ambient clump Σcl, and ratio of the core’s initial rotational to gravitational energy βc. Evolutionary sequences with −2 various Mc,Σcl, βc are constructed. We find that in a fiducial model with Mc = 60 M⊙,Σcl =1gcm and βc =0.02, > the final mass of the protostar reaches at least ∼ 26 M⊙, making the final star formation efficiency ∼0.43. For each of the evolutionary tracks, radiation transfer simulations are performed at selected stages, with temperature profiles, spectral energy distributions (SEDs), and multi-wavelength images produced. At a given stage, envelope temperature is depends strongly on Σcl, with higher temperatures in a higher Σcl core, but only weakly on Mc. The SED and MIR images depend sensitively on the evolving outflow cavity, which gradually widens as the protostar grows. The < fluxes at ∼100 µm increase dramatically, and the far-IR peaks move to shorter wavelengths. The influence of Σcl and βc (which determines disk size) are discussed. We find that, despite scatter caused by different Mc, Σcl, βc, and inclinations, sources at a given evolutionary stage appear in similar regions of color-color diagrams, especially when > using colors with fluxes at ∼70 µm, where scatter due to inclination is minimized, implying that such diagrams can be useful diagnostic tools of evolutionary stages of massive protostars. We discuss how intensity profiles along or perpendicular to the outflow axis are affected by environmental conditions and source evolution, and can thus act as additional diagnostics of the massive star formation process. Accepted by ApJ http://arxiv.org/pdf/1312.3370.pdf

Accretion and OH Photodissociation at a Nearby T Tauri System in the beta Pictoris Moving Group B. Zuckerman1, Laura Vican1, and David R. Rodriguez2 1 Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA 2 Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago, Chile E-mail contact: ben at astro.ucla.edu We present spectra of an M-type, binary (LDS 5606) that belongs to the nearby ∼20 Myr old β Pictoris moving group. Both stars are very dusty; the dustier member displays optical emission lines from eight elements indicative of ongoing mass accretion. The spectra of both stars contain oxygen forbidden line emission at 6302 and 5579 A,˚ consistent with a recent model of far ultraviolet photodissociation of OH molecules in a circumstellar disk. These are the oldest dwarf stars presently known to display such a phenomena. The spectral energy distribution of the dustier star indicates substantial quantities of dust as hot as 900 K, and its fractional infrared luminosity (LIR)/Lbol) is almost as large as that of the main sequence record holder, V488 Per. The LDS 5606 binary joins a remarkable group of very dusty, old, T Tauri stars that belong to widely separated multiple systems.

41 Accepted by ApJ http://arxiv.org/pdf/1404.7481

Abstracts of recently accepted major reviews

Turbulence in the Interstellar Medium D. Falceta-Gon¸calves1,2, G. Kowal2, E. Falgarone3, and A.C.-L. Chian4,5,6 1 SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, UK 2 Escola de Artes, Ciencias e Humanidades, Universidade de Sao Paulo, Rua Arlindo Bettio 1000, CEP 03828-000, Sao Paulo, Brazil 3 LERMA/LRA, CNRS, Ecole Normale Superieure and Observatoire de Paris, 24 rue Lhomond, 75231 Paris Cedex, France 4 Observatoire de Paris, LESIA, CNRS, 92190 Meudon, France 5 National Institute for Space Research (INPE) and World Institute for Space Environment Research (WISER), P. O. Box 515, 12227-010 S˜ao Jos´edos Campos-SP, Brazil 6 School of Mathematical Sciences, University of Adelaide, Adelaide, SA 5005, Australia E-mail contact: dfalceta at usp.br Turbulence is ubiquitous in the interstellar medium and plays a major role in several processes such as the formation of dense structures and stars, the stability of molecular clouds, the amplification of magnetic fields, and the re- acceleration and diffusion of cosmic rays. Despite its importance, interstellar turbulence, alike turbulence in general, is far from being fully understood. In this review we present the basics of turbulence physics, focusing on the statistics of its structure and energy cascade. We explore the physics of compressible and incompressible turbulent flows, as well as magnetized cases. The most relevant observational techniques that provide quantitative insights of interstellar turbulence are also presented. We also discuss the main difficulties in developing a three-dimensional view of interstellar turbulence from these observations. Finally, we briefly present what could be the the main sources of turbulence in the interstellar medium. Accepted by Nonlinear Processes in Geophysics http://arxiv.org/pdf/1404.3691

The Link between Magnetic Fields and Cloud/Star Formation Hua-bai Li1,2, Alyssa Goodman3, T. K. Sridharan3, Martin Houde4,5, Zhi-Yun Li6, Giles Novak7 and Kwok Sun Tang1 1 The Chinese University of Hong Kong 2 Max Planck Institute for Astronomy 3 Harvard-Smithsonian Center for Astrophysics 4 University of Western Ontario 5 California Institute of Technology 6 University of Virginia 7 Northwestern University E-mail contact: hbli at phy.cuhk.edu.hk

42 The question whether magnetic fields play an important role in the processes of molecular cloud and star formation has been debated for decades. Recent observations have revealed a simple picture that may help illuminate these questions: magnetic fields have a tendency to preserve their orientation at all scales that have been probed - from 100-pc scale inter-cloud media down to sub-pc scale cloud cores. This ordered morphology has implications for the way in which self-gravity and turbulence interact with magnetic fields: both gravitational contraction and turbulent velocities should be anisotropic, due to the influence of dynamically important magnetic fields. Such anisotropy is now observed. Here we review these recent observations and discuss how they can improve our understanding of cloud/star formation. Accepted for publication as a chapter in Protostars and Planets VI, University of Arizona Press (2014) http://arxiv.org/pdf/1404.2024

43 New Jobs

Postdoctoral Fellowship in Star Formation

Applications are invited for a postdoctoral fellowship in observational studies of low-mass star formation. The fellow will work with Dr. Phil Myers and collaborators on studies of protostar and disk accretion, accretion stopping, and multiplicity in dense molecular cloud cores. He or she will analyze JVLA and SMA data, and will lead followup proposals to ALMA and other telescopes. He or she will have access to CfA facilities, funds for research and travel, and opportunity to pursue independent research projects. The position is available starting October 1, 2014, extending for two years, with possible renewal for a third year. The annual stipend for 2014 is $58,000, plus relocation reimbursement up to $4,000. Smithsonian group health insurance coverage is fully paid for individuals and families. The applicant must have a Ph.D. in astronomy, physics, or a related field by the start date. Experience in star formation studies, in observations at millimeter and submillimeter wavelengths, and in interferometry are desirable. To apply, send a pdf package to cores [email protected], including a cover letter, CV, publication list, and a description of current research and plans, up to three pages in length. The applicant should arrange for three letters of reference to be submitted to the same address. Applications received before July 1, 2014 will receive full consideration, but review of applications will continue until the position is filled. The Harvard-Smithsonian Center for Astrophysics is an Equal Opportunity/Affirmative Action Employer where all qualified applicants receive equal consideration for employment without regard to race, creed, color, sex or national origin.

Postdoctoral Position in Star and Planet Formation

The Department of Physics & Astronomy at the University of Toledo invites applications for a postdoctoral position in the area of Star and Planet Formation. The postdoc will work with Dr. Tom Megeath on a program to study protostars in the Orion molecular clouds using data from the Spitzer, Herschel, Hubble, and ALMA observatories. A particular focus will be to work with Hubble and ALMA data that resolve protostellar envelopes and disks. The successful applicant will work with Tom Megeath and Will Fischer (now at Goddard Space Flight Center) on existing HST data and an accepted ALMA program to study edge on protostars. Experience working with radiative transfer codes and millimeter interferometry will be of great benefit. The postdoc will be part of an international team collaborating on a comprehensive study of star formation in Orion using infrared and radio telescopes. The University of Toledo is a partner in the 4.3 meter Discovery Channel Telescope operated by Lowell Observatory, and the postdoc will be encouraged to submit proposals and use this facility. The appointment will be for two years. Requirements are a Ph.D. in astronomy and research experience in star and planet formation. Please send a cover letter, CV, a statement of research interest up to one page in length, and contact information for references to [email protected] by June 15th.

44 Summary of Upcoming Meetings

The Formation of the Solar System 13 - 15 May 2014 MPIfR, Bonn, Germany https://indico.mpifr-bonn.mpg.de/theFormationOfTheSolarSystem The Olympian Symposium on Star Formation 26 - 30 May 2014 Paralia Katerini’s, Mount Olympus, Greece http://zuserver2.star.ucl.ac.uk/~ossf14/ EPoS2014 The Early Phase of Star Formation 1 - 6 June 2014 Ringberg Castle, Tegernsee, Germany http://www.mpia-hd.mpg.de/homes/stein/EPoS/epos.php The Dance of Stars: Dense Stellar Systems from Infant to Old 2 - 6 June 2014 Bad Honnef, Germany http://www.astro.uni-bonn.de/$\sim$sambaran/DS2014/index.html The Submillimeter Array: First Decade of Discovery 9 - 10 June, 2014, Cambridge, MA, USA http://www.cfa.harvard.edu/sma/events/smaConf/ The 18th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun 9 - 13 June 2014 Flagstaff, Arizona, USA http://www2.lowell.edu/workshops/coolstars18/ Summer School on Protoplanetary Disks: Theory and Modeling meet Observations 16 - 20 June 2014 Groningen, The Netherlands http://www.diana-project.com/summer-school Workshop on Dense Cores: Origin, Evolution, and Collapse 27 - 30 July 2014 Monterey, CA, USA http://www.aas.org/meetings/aastcs4 Characterizing Planetary Systems Across the HR Diagram 28 July - 1 August 2014 Inst. for Astronomy, Cambridge, USA http://www.ast.cam.ac.uk/meetings/2013/AcrossHR Planet Formation and Evolution 2014 8 - 10 September 2014 Kiel, Germany http://www.astrophysik.uni-kiel.de/kiel2014 Living Together: Planets, Stellar Binaries and Stars with Planets 8 - 12 September 2014 Litomysl Castle, Litomysl, Czech Republic http://astro.physics.muni.cz/kopal2014/ Galactic and Extragalactic Star Formation 8 - 12 September 2014 Marseille, France http://gesf2014.lam.fr Thirty Years of Beta Pic and Debris Disk Studies 8 - 12 Sepetmber 2013 Paris, France http://betapic30.sciencesconf.org Towards Other II. The Star-Planet Connection 15 - 19 September 2014 Portugal http://www.astro.up.pt/toe2014

45 Star Formation Across Space and Time 11-14 November 2014 Noordwijk, The Netherlands http://congrexprojects.com/14a09/

45th “Saas-Fee Advanced Course”: From Protoplanetary Disks to Planet Formation 15-20 March 2015, Switzerland no website yet Other meetings: http://www1.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/meetings/

Moving ... ??

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

46 New Books

Exploring the Formation and Evolution of Planetary Systems Edited by Mark Booth, Brenda C. Matthews, James R. Graham

These are the proceedings of IAU Symposium No. 299 held 2–7 June 2013 in Victoria, British Columbia, Canada. They report on recent results in the field of planet formation and detection and covers the range from the detailed imaging of protoplanetary disks to the modeling of planetary atmospheres. Recent years have seen a dramatic increase in our understanding of planetary systems. Initially, new exoplanets were discovered through the effects they have on their parent stars - whether through radial velocity, transits or microlensing methods - but now the technology and the techniques have been developed to image light from exoplanets directly. Vast improvements have also been made in our ability to resolve circumstellar matter from protoplanetary disks, through transition disks to debris disks. These dramatic new observations have led to new advances in our theoretical understanding of the formation and evolution of planetary systems. The book is up-to-date, and appeared in print only six months after the end of the meeting. The following lists the sections of the book: 1 High Contrast AO Imaging: Latest Results in Direct Exoplanet Imaging 2 Peering into Circumstellar Disks: Transformative Interferometry & High Resolution Imaging 3 Building Planets in Protoplanetary Disks: Earliest Evidence 4 Co-evolution of Disks and Planetary Systems 5 Detailed Studies of Known Exoplanets and Exoplanet Systems 6 Debris Disks as Signposts of Planetary Systems 7 Evolution of Planetary Systems

Cambridge University Press 2013, ISBN 9781107045200 406 pages, hardcover US$118.75 Available from http://http://www.cambridge.org/ua/academic/subjects/astronomy/extrasolar-planets-and-astrobiolog

47 Passings

Karen M. Strom

With great sadness we report the passing of Karen M. Strom from a sudden illness. Karen was a member of the scientific staff of Kitt Peak National Observatory (now part of the National Optical Astronomy Observatories) from 1972 to 1982. At Kitt Peak she led or contributed to numerous papers on T-Tauri stars, their circumstellar disks, envelopes, and outflows, including studies of nebular Herbig-Haro objects. She also carried out research on other aspects of stellar evolution, as well as important work investigating the stellar populations of other galaxies. She, along with her husband Steve and their colleagues, conducted some of the first infrared surveys of star-forming regions. In addition she pioneered early approaches to image processing based on these data. That work contributed to the development of IRAF at NOAO. From 1983 until her retirement from astronomy in 1998, she was a Research Professor in the Five College Astronomy Department (FCAD) at the University of Massachusetts, Amherst, where she continued her scientific work. As an astronomer Karen is perhaps best known for her estimate of the lifetimes of circumstellar accretion disks surrounding T Tauri stars in the Taurus- dark cloud (a fundamental constraint on theories of gas giant planet formation) as well as multi-wavelength studies of the young stellar populations in the L1641 region of the Orion A molecular cloud and other regions. Karen was much more than an accomplished scientific researcher and mentor to numerous young scientists. She was an early innovator on the World Wide Web, and one of its early proponents in academe. She led the development of one of the first academic departmental websites (highlighting UMass and FCAD astronomy research), and pioneered hypertext for astronomy research and education (including some of the first digital publishing of PhD dissertations). She also created the first public clickable map for the state of Massachusetts. After retiring from astronomy, Karen developed websites for Native American artists, consulted on web-based edu- cation, and resumed a long-standing interest in photography. She is publisher or co-publisher of numerous e-books, including ”Sticks and Stones: an alphabet book for the 21st century”, and ”An Armchair Travelers Guide to Death Valley. Her fine art photography is distributed both electronically (of course) and through galleries. Karen became a world traveler in the service of her art, and recently returned from a travel adventure including stops in Istanbul, Venice, Barcelona, and Bilbao. She and her husband of 54 years, Stephen E. Strom, dared to take an excursion over Cappadocia in a hot air balloon. On that trip she took thousands of images that will one day be sorted and compiled by her grandchildren, in her honor. Karen Marie Lewallen was born in 1941 in Fairfax, Oklahoma and grew up in Henryetta, Oklahoma. She graduated from Harvard College in 1964 (in one of the first classes where women were awarded such a degree), worked at the Smithsonian Astrophysical Observatory and SUNY Stony Brook before moving to Kitt Peak. In 1995 she received an honorary Ph.D. in Astronomy from Instituto Nacional de Astrof´ısica, Opticaˆ y Electr´onica (INAOE) in Puebla, Mexico for her many scientific contributions. She is survived by her husband Steve, daughters Kathy and Julie, and sons Robert and David. She had six grandchildren. 4604 Stekarstrom is named in her honor, along with her husband. Some of her work can be seen at http://karenstrom.com and glimpses of a rich life shared with others can be found at http://karenstrom.org.

Lori Allen Michael Meyer David Strom Rob Seaman

48 Short Announcements

Planet Formation Imager (PFI) Project – Call for Participation

The Planet Formation Imager (PFI) Kick-off Committee announces an Open Call for Participation in PFI Concept Studies. The ambitious goal of PFI is to image planet-forming disks in nearby star-forming regions with high enough spatial resolution to resolve the key physical processes at work, to witness planet formation live as it happens with ∼ 0.1 AU resolution or better. Scientists from more than a dozen different institutes in six countries have begun planning for initial Concept Studies, an effort led by Project Director John Monnier (U. Michigan), Project Scientist Stefan Kraus (U. Exeter), and Project Architect David Buscher (U. Cambridge). Our top priorities for the next 12-24 months will be to define the most exciting areas of science to drive the instrument concept and at the same time determine feasible architectures for meeting the science goals. We seek contributions from the international astronomical community and invite participants to join the PFI Science Working Group or the Technical Working Group. For more information and to sign up to participate, please see http://www.planetformationimager.org (initial deadline to join working groups is June 16, 2014). Website: http://www.planetformationimager.org Contact: [email protected]

HANDBOOK OF IRON by Vagn F. Buchwald Free Electronic Edition now Available http://evols.library.manoa.hawaii.edu/handle/10524/33750

The Handbook of Iron Meteorites was originally published by the University of California Press in 1975 for the Center for Studies at Arizona State University. It has been digitized at the University of Hawaii as it is still an extraordinarily valuable resource and is no longer in print. This is a monumental book in three volumes containing 1426 pages, 2124 figures, eight appendices and a supple- ment. Volume 1 provides a general introduction to meteorites, fireballs, and impact craters and to the mineralogy, composition, and properties of iron meteorites. It also contains appendices of information about iron meteorites. Volumes 2 and 3 contain descriptions of about 600 iron meteorites–nearly all those that were known and accessible in 1975. These descriptions include information about the structure, mineralogy, and composition of each iron meteorite, its thermal and impact history, discovery and subsequent history, as well as a list of museum holdings. A guide for users can be found on page 245 at the beginning of Volume 2. At the end of Volume 3 on pages 1376-1418 there is a supplement containing information about eleven meteorites that were studied after 1973 plus additional notes and photographs for a few other iron meteorites. The original prints for the figures were preserved by Vagn Buchwald and these have been scanned by the Natural History Museum of Denmark. They can be accessed by figure number: http://geologi.snm.ku.dk/english/samlinger/meteorit/handbook-iron-meteorites/

Ed Scott, University of Hawaii

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