DOCSLIB.ORG

ALIGNMENT BETWEEN PROTOSTELLAR OUTFLOWS and FILAMENTARY STRUCTURE Ian W

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
ALIGNMENT BETWEEN PROTOSTELLAR OUTFLOWS and FILAMENTARY STRUCTURE Ian W Draft version July 27, 2017 Preprint typeset using LATEX style emulateapj v. 01/23/15 ALIGNMENT BETWEEN PROTOSTELLAR OUTFLOWS AND FILAMENTARY STRUCTURE Ian W. Stephens1, Michael M. Dunham2,1, Philip C. Myers1, Riwaj Pokhrel1,3, Sarah I. Sadavoy1, Eduard I. Vorobyov4,5,6, John J. Tobin7,8, Jaime E. Pineda9, Stella S. R. Offner3, Katherine I. Lee1, Lars E. Kristensen10, Jes K. Jørgensen11, Alyssa A. Goodman1, Tyler L. Bourke12,Hector´ G. Arce13, Adele L. Plunkett14 Draft version July 27, 2017 ABSTRACT We present new Submillimeter Array (SMA) observations of CO(2{1) outflows toward young, em- bedded protostars in the Perseus molecular cloud as part of the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey. For 57 Perseus protostars, we characterize the orientation of the outflow angles and compare them with the orientation of the local filaments as derived from Herschel observations. We find that the relative angles between outflows and filaments are inconsistent with purely parallel or purely perpendicular distributions. Instead, the observed dis- tribution of outflow-filament angles are more consistent with either randomly aligned angles or a mix of projected parallel and perpendicular angles. A mix of parallel and perpendicular angles requires perpendicular alignment to be more common by a factor of ∼3. Our results show that the observed distributions probably hold regardless of the protostar's multiplicity, age, or the host core's opacity. These observations indicate that the angular momentum axis of a protostar may be independent of the large-scale structure. We discuss the significance of independent protostellar rotation axes in the general picture of filament-based star formation. Keywords: stars: formation { galaxies: star formation { stars: protostars { ISM: jets and outflows { ISM: clouds { ISM: structure 1. INTRODUCTION be hierarchically transferred from molecular clouds to Many stars form in filamentary structures with widths cores to protostars (e.g., Bodenheimer 1995). For a star- of order 0.1 pc (e.g., Arzoumanian et al. 2011). While forming filament, large-scale flows are probably either the exact shape of filaments is debated, e.g., cylinders onto the short axes of the filament from its cloud (either versus ribbons (Auddy et al. 2016), filaments are de- via accretion from the cloud or accretion via a collision) fined by a long axis and two much shorter axes. Dense or along the long filamentary axis. In a simplistic, non- cores (∼0.1 pc scale) either form within the filaments or turbulent scenario where one of the flows about the three form simultaneously with the filaments (Chen & Ostriker filamentary axes dominates, a core will likely rotate pri- 2015). Inhomogeneous flow or shear from colliding flows marily parallel or perpendicular to the parent filament. can torque cores (e.g., Fogerty et al. 2016; Clarke et al. If the angular momentum direction at the protostellar 2017). Classically, angular momentum is expected to scale is inherited from this core scale, the rotation axes of newly formed protostars will also be preferentially par- 1 Harvard-Smithsonian Center for Astrophysics, 60 Garden allel or perpendicular to the filaments. Street, Cambridge, MA, USA [email protected] One way to empirically test the alignment between a 2 Department of Physics, State University of New York at Fre- protostar's spin and its filamentary structure is to ob- donia, 280 Central Ave, Fredonia, NY 14063, USA 3 Department of Astronomy, University of Massachusetts, serve a protostar's outflow direction and compare it to Amherst, MA 01003, USA the filamentary structure as probed by dust emission. 4 Institute of Fluid Mechanics and Heat Transfer, TU Wien, Vi- By using this method across five nearby star-forming re- enna, 1060, Austria gions, Anathpindika & Whitworth(2008) found sugges- 5 Research Institute of Physics, Southern Federal University, Stachki Ave. 194, Rostov-on-Don, 344090, Russia tive evidence that outflows (as traced by scattered light) 6 University of Vienna, Department of Astrophysics, Vienna, tend to be preferentially perpendicular to filaments. On 1180, Austria the other hand, Davis et al.(2009) found that in Orion, arXiv:1707.08122v1 [astro-ph.GA] 25 Jul 2017 7 Homer L. Dodge Department of Physics and Astronomy, Uni- the orientation between outflows (as traced by H ) and versity of Oklahoma, 440 W. Brooks Street, Norman, OK 73019, 2 USA filaments appear random. A well-focused study that an- 8 Leiden Observatory, Leiden University, P.O. Box 9513, 2300- alyzes the outflow-filament angles is needed to reconcile RA Leiden, The Netherlands this disagreement. 9 Max-Planck-Institut f¨ur extraterrestrische Physik, D-85748 The rotation axis of a protostar, or even the parent Garching, Germany 10 Centre for Star and Planet Formation, Niels Bohr Institute protostellar core, could also be independent of its na- and Natural History Museum of Denmark, University of Copen- tal filamentary structure. Some observations have shown hagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark that the angular momentum vectors of cores themselves 11 Niels Bohr Institute and Center for Star and Planet Forma- may be randomly distributed about the sky, regardless tion, Copenhagen University, DK-1350 Copenhagen K., Denmark 12 SKA Organization, Jodrell Bank Observatory, Lower With- of the cloud, core, or filamentary structure (Heyer 1988; ington, Macclesfield, Cheshire SK11 9DL, UK Myers et al. 1991; Goodman et al. 1993; Tatematsu et al. 13 Department of Astronomy, Yale University, New Haven, CT 2016). Multiplicity could also affect rotation axes. In the 06520, USA 14 European Southern Observatory, Av. Alonso de Cordova Submillimeter Array (SMA, Ho et al. 2004) large project 3107, Vitacura, Santiago de Chile, Chile called the Mass Assembly of Stellar Systems and their 2 Evolution with the SMA (MASSES; co-PIs: Michael data published in Lee et al. 2015, 2016) since these ob- Dunham and Ian Stephens), Lee et al.(2016) found that servations were either better quality and/or at higher outflows of wide-binary pairs (i.e., binary pairs sepa- resolution. These published PAs each came from obser- rated by 1000 AU and 10,000 AU) are typically randomly vations of one of three different J rotational transitions aligned or perpendicular (but not parallel) to each other. of CO: CO(1{0), CO(2{1), and CO(3{2). The rest fre- Radiation-magnetohydrodynamic simulations by Offner quencies for these three spectral lines are 115.27120 GHz, et al.(2016) of slightly magnetically-supercritical turbu- 230.53796 GHz, and 345.79599 GHz, respectively. lent cores found the same results for wide-binary pairs. 2.2. Herschel-derived Optical Depth Maps These simulations suggest that the direction of the proto- stellar spin axis can evolve significantly during formation, Herschel is well-suited for finding filaments in Perseus indicating that, at least for wide-binaries, the rotation given its resolution and wavelength range. The resolu- axes are independent of the large-scale structure. tion at the longest Herschel wavelength (500 µm) is 3600 In this paper, we aim to observationally test whether or ∼0.04 pc at the distance of Perseus (235 pc, Hirota or not a preferential alignment exists between the local et al. 2008). Star-forming filaments have temperatures filamentary elongation and the angular momentum axis of ∼10 to 20 K, and thus the dust continuum will peak as traced by outflows. To test such alignment, we use within the Herschel bands (70 µm to 500 µm). These new CO observations from the MASSES survey to trace wavebands can be used to approximate the optical depth the molecular outflows in the Perseus molecular cloud. and the column density of Perseus filaments. Indeed, Along with ancillary data, we determine accurate pro- several studies have already created optical depth or col- jected outflow position angles (PAs) for 57 Class 0 and I umn density maps of the Perseus molecular cloud using protostars. The MASSES survey provides uniform spa- Herschel observations, including Sadavoy et al.(2014), tial coverage of the same molecular line tracers in a single Zari et al.(2016), and Abreu-Vicente et al.(2016). All cloud, and only focuses on young sources { Class 0 and I three of the aforementioned studies assumed a modified protostars. Since these protostars are young, their par- blackbody with a specific intensity of ent filamentary structure has had less time to change in I = B (T )(1 − e−τν ) ≈ B (T )τ ; (1) morphology since the birth of the stars. These outflow ν ν ν ν observations can then be compared to the filamentary where Bν is the blackbody function at temperature T structure as observed by the Herschel Gould Belt sur- and τν is the optical depth. τν is assumed to follow a β vey (e.g., Andr´eet al. 2010). power-law function of the form τν / ν , where β is the We describe the observations used in Section2 and the dust emissivity index. The dust column density, Ndust, outflow/filament PA extraction techniques in Section3. can be calculated assuming τν = Ndustκν , where κν is We present the results in Section4 and discuss their pos- the dust opacity. Each study assumed τν and T to be sible implications in Section5. Finally, we summarize the free parameters. main results in Section6. While these studies varied slightly, e.g., on their as- sumption for β, the resulting maps are very similar. We choose to use the 353 GHz optical depth (τ353 GHz) map 2. OBSERVATIONS from Zari et al.(2016) since this map has been made 2.1. Outflow and Continuum Data publicly available. Zari et al.(2016) assumed a value For the Perseus protostellar outflows studied in this pa- of β = 2, and they did not convert the τ353 GHz maps per, we introduce new, unpublished MASSES CO(2{1) to column density.
Load more

Recommended publications
  • New Herbig±Haro Objects and Giant Outflows in Orion
    Mon. Not. R. Astron. Soc. 310, 331±354 (1999) New Herbig±Haro objects and giant outflows in Orion S. L. Mader,1 W. J. Zealey,1 Q. A. Parker2 and M. R. W. Masheder3,4 1Department of Engineering Physics, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia 2Anglo-Australian Observatory, Coonabarabran, NSW 2357, Australia 3Department of Physics, University of Bristol, Bristol BS8 1TL 4Netherlands Foundation for Research in Astronomy, PO Box 2, 7990 AA Dwingeloo, the Netherlands Accepted 1999 June 29. Received 1999 May 11; in original form 1998 June 25 ABSTRACT We present the results of a photographic and CCD imaging survey for Herbig±Haro (HH) objects in the L1630 and L1641 giant molecular clouds in Orion. The new HH flows were initially identified from a deep Ha film from the recently commissioned AAO/UKST Ha Survey of the southern sky. Our scanned Ha and broad-band R images highlight both the improved resolution of the Ha survey and the excellent contrast of the Ha flux with respect to the broad-band R. Comparative IVN survey images allow us to distinguish between emission and reflection nebulosity. Our CCD Ha,[Sii], continuum and I-band images confirm the presence of a parsec-scale HH flow associated with the Ori I-2 cometary globule, and several parsec-scale strings of HH emission centred on the L1641-N infrared cluster. Several smaller outflows display one-sided jets. Our results indicate that, for declinations south of 268 in L1641, parsec-scale flows appear to be the major force in the large-scale movement of optical dust and molecular gas.
    [Show full text]
  • Chemical Survey Toward Young Stellar Objects in the Perseus Molecular Cloud Complex
    The Astrophysical Journal Supplement Series, 236:52 (25pp), 2018 June https://doi.org/10.3847/1538-4365/aabfe9 © 2018. The American Astronomical Society. Chemical Survey toward Young Stellar Objects in the Perseus Molecular Cloud Complex Aya E. Higuchi1 , Nami Sakai1 , Yoshimasa Watanabe2 , Ana López-Sepulcre3,4, Kento Yoshida1,5, Yoko Oya5 , Muneaki Imai5 , Yichen Zhang1 , Cecilia Ceccarelli3 , Bertrand Lefloch3, Claudio Codella6 , Rafael Bachiller7 , Tomoya Hirota8 , Takeshi Sakai9 , and Satoshi Yamamoto5 1 RIKEN Cluster for Pioneering Research, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan; [email protected] 2 Division of Physics, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan 3 Univ. Grenoble Alpes, CNRS, Institut de Plan étologie et d’Astrophysique de Grenoble (IPAG), F-38000 Grenoble, France 4 Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, Domaine Universitaire de Grenoble, F-38406 Saint-Martin d’H ères, France 5 Department of Physics, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan 6 INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125, Firenze, Italy 7 IGN Observatorio Astronómico Nacional, Apartado 1143, E-28800 Alcalá de Henares, Spain 8 National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588, Japan 9 Department of Communication Engineering and Informatics, Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofugaoka, Chofu, Tokyo 182-8585, Japan Received 2017 December 1; revised 2018 April 20; accepted 2018 April 21; published 2018 June 20 Abstract The chemical diversity of gas in low-mass protostellar cores is widely recognized. In order to explore the origin of this diversity, a survey of chemical composition toward 36 Class 0/I protostars in the Perseus molecular cloud complex, which are selected in an unbiased way under certain physical conditions, has been conducted with IRAM30mandNRO45m telescope.
    [Show full text]
  • Technion, Israel Abstract
    JETS before, during, and after explosions and in powering intermediate luminosity optical transients (ILOTs) Noam Soker Technion, Israel Abstract I will describe recent results on the role of JETS in exploding core collapse supernovae (CCSNe) and in powering Intermediate Luminosity Optical Transients (ILOTs), and will compare the results with the most recent observations and with other theoretical studies. I will discuss new ideas of processes that become possible by jets, such as the jittering jets explosion mechanism of massive stars aided by neutrino heating, the formation of Type IIb CCSNe by the Grazing Envelope Evolution (GEE), and common envelope jets supernovae (CEJSNe). 1. Introduction JETS 2. Jets Before 2.1 Jets shape pre-explosion circumstellar matter Similar outer rings in SN 1987A and in the planetary nebula jet jet SN 1987A 19987A Broken inner ring in SN 1987A and in the Necklace planetary nebulae jet Necklace planetary nebula In both planetary nebulae there is a binary system at jet (Corradi et al. 2011) the center. The compact companion launches the SN 1987A jets as it accretes mass from the giant progenitor. 2.2 Jets launched by a companion power pre-explosion outbursts Can be a main sequence companion as in the Great Eruption of Eta Carinae (Kashi, A. & Soker, N. in several papers). Can be a neutron star that enters the envelope (Gilkis, A., Kashi, A., Soker, N. 2019), or that accretes from the inflated envelope (Danieli, B. & Soker, N. 2019) 2.3 Type IIb supernovae by the grazing envelope evolution Jet-driven mass loss prevents common envelope and leads to the formation of a Type IIb supernova.
    [Show full text]
  • A Massive Bipolar Outflow and a Dusty Torus with Large Grains in the Preplanetary Nebula Iras 22036+5306 R
    The Astrophysical Journal, 653:1241Y1252, 2006 December 20 # 2006. The American Astronomical Society. All rights reserved. Printed in U.S.A. A MASSIVE BIPOLAR OUTFLOW AND A DUSTY TORUS WITH LARGE GRAINS IN THE PREPLANETARY NEBULA IRAS 22036+5306 R. Sahai,1 K. Young,2 N. A. Patel,2 C. Sa´nchez Contreras,3 and M. Morris4 Received 2006 June 19; accepted 2006 August 10 ABSTRACT We report high angular resolution (100)COJ ¼ 3Y2 interferometric mapping using the Submillimeter Array (SMA) of IRAS 22036+5306 (I22036), a bipolar preplanetary nebula (PPN) with knotty jets discovered in our HST snapshot survey of young PPNs. In addition, we have obtained supporting lower resolution (1000) CO and 13CO J ¼ 1Y0 observations with the Owens Valley Radio Observatory (OVRO) interferometer, as well as optical long-slit echelle spectra at the Palomar Observatory. The CO J ¼ 3Y2 observations show the presence of a very fast (220 km sÀ1), 39 À1 highly collimated, massive (0.03 M ) bipolar outflow with a very large scalar momentum (about 10 gcms ), and the characteristic spatiokinematic structure of bow shocks at the tips of this outflow. The H line shows an absorption feature blueshifted from the systemic velocity by 100 km sÀ1, which most likely arises in neutral interface material between the fast outflow and the dense walls of the bipolar lobes at low latitudes. The fast outflow in I22036, as in most PPNs, cannot be driven by radiation pressure. We find an unresolved source of submillimeter (and millimeter- wave) continuum emission in I22036, implying a very substantial mass (0.02Y0.04 M ) of large (radius k1 mm), cold (P50 K) dust grains associated with I22036’s toroidal waist.
    [Show full text]
  • Physical Processes in the Interstellar Medium
    Physical Processes in the Interstellar Medium Ralf S. Klessen and Simon C. O. Glover Abstract Interstellar space is filled with a dilute mixture of charged particles, atoms, molecules and dust grains, called the interstellar medium (ISM). Understand- ing its physical properties and dynamical behavior is of pivotal importance to many areas of astronomy and astrophysics. Galaxy formation and evolu- tion, the formation of stars, cosmic nucleosynthesis, the origin of large com- plex, prebiotic molecules and the abundance, structure and growth of dust grains which constitute the fundamental building blocks of planets, all these processes are intimately coupled to the physics of the interstellar medium. However, despite its importance, its structure and evolution is still not fully understood. Observations reveal that the interstellar medium is highly tur- bulent, consists of different chemical phases, and is characterized by complex structure on all resolvable spatial and temporal scales. Our current numerical and theoretical models describe it as a strongly coupled system that is far from equilibrium and where the different components are intricately linked to- gether by complex feedback loops. Describing the interstellar medium is truly a multi-scale and multi-physics problem. In these lecture notes we introduce the microphysics necessary to better understand the interstellar medium. We review the relations between large-scale and small-scale dynamics, we con- sider turbulence as one of the key drivers of galactic evolution, and we review the physical processes that lead to the formation of dense molecular clouds and that govern stellar birth in their interior. Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Straße 2, 69120 Heidelberg, Germany e-mail: [email protected], [email protected] 1 Contents Physical Processes in the Interstellar Medium ...............
    [Show full text]
  • Planck Early Results. XX. New Light on Anomalous Microwave Emission from Spinning Dust Grains
    A&A 536, A20 (2011) Astronomy DOI: 10.1051/0004-6361/201116470 & c ESO 2011 Astrophysics Planck early results Special feature Planck early results. XX. New light on anomalous microwave emission from spinning dust grains Planck Collaboration: P. A. R. Ade72, N. Aghanim46,M.Arnaud58, M. Ashdown56,4, J. Aumont46, C. Baccigalupi70,A.Balbi28, A. J. Banday77,7,63,R.B.Barreiro52, J. G. Bartlett3,54,E.Battaner79, K. Benabed47, A. Benoît45,J.-P.Bernard77,7, M. Bersanelli25,41, R. Bhatia5, J. J. Bock54,8, A. Bonaldi37,J.R.Bond6,J.Borrill62,73,F.R.Bouchet47, F. Boulanger46, M. Bucher3,C.Burigana40,P.Cabella28, B. Cappellini41, J.-F. Cardoso59,3,47,S.Casassus76, A. Catalano3,57, L. Cayón18, A. Challinor49,56,10, A. Chamballu43, R.-R. Chary44,X.Chen44,L.-Y.Chiang48, C. Chiang17,P.R.Christensen67,29,D.L.Clements43, S. Colombi47, F. Couchot61, A. Coulais57, B. P. Crill54,68, F. Cuttaia40,L.Danese70, R. D. Davies55,R.J.Davis55,P.deBernardis24,G.deGasperis28,A.deRosa40, G. de Zotti37,70, J. Delabrouille3, J.-M. Delouis47, C. Dickinson55, S. Donzelli41,50,O.Doré54,8,U.Dörl63, M. Douspis46, X. Dupac32, G. Efstathiou49,T.A.Enßlin63,H.K.Eriksen50, F. Finelli40, O. Forni77,7, M. Frailis39, E. Franceschi40,S.Galeotta39, K. Ganga3,44,R.T.Génova-Santos51,30,M.Giard77,7, G. Giardino33, Y. Giraud-Héraud3, J. González-Nuevo70,K.M.Górski54,81,S.Gratton56,49, A. Gregorio26, A. Gruppuso40,F.K.Hansen50,D.Harrison49,56,G.Helou8, S. Henrot-Versillé61, D. Herranz52,S.R.Hildebrandt8,60,51,E.Hivon47, M.
    [Show full text]
  • VLBI Monitoring Observations of Water Masers Around the Semi
    VLBI Monitoring Observations of Water Masers Around the Semi-Regular Variable Star R Crateris Jos´eK. Ishitsuka ,1 Hiroshi Imai,2,3 Toshihiro Omodaka,4 Munetaka Ueno,1 Osamu Kameya,2,3 Tetsuo Sasao,3 Masaki Morimoto,5 Takeshi Miyaji,3,6 Jun-ichi Nakajima,7 and Teruhiko Watanabe4 1Department of Earth Science and Astronomy, University of Tokyo, Komaba, Tokyo 153-8902 [email protected] 2Mizusawa Astrogeodynamics Observatory, National Astronomical Observatory, Mizusawa, Iwate 023-0861 3VERA Project Office, National Astronomical Observatory, Mitaka, Tokyo 181-8588 4Faculty of Science, Kagoshima University, Kagoshima, Kagoshima 890-0065 5Nishi-Harima Astronomical Observatory, Sayo, Hyogo 679-5313 6Nobeyama Radio Observatory, National Astronomical Observatory, Minamisaku, Nagano 384-1305 7Kashima Space Research Center, Communications Research Laboratory, Kashima, Ibaraki 314-0012 (Received 2000 December 8; accepted 2001 September 24) Abstract We monitored water-vapor masers around the semi-regular variable star R Crateris with the Japanese VLBI Network (J-Net) at the 22 GHz band during four epochs with intervals of one month. The relative proper motions and Doppler- velocity drifts of twelve maser features were measured. Most of them existed for longer than 80 days. The 3-D kinematics of the features indicates a bipolar expanding flow. The major axis of the asymmetric flow was estimated to be at P.A. = 136◦. The existence of a bipolar outflow suggests that a Mira variable star had already formed a bipolar outflow. The water masers are in a region of apparent minimum radii of arXiv:astro-ph/0112302v1 13 Dec 2001 1.3 × 1012 m and maximum radii of 2.6 × 1012 m, between which the expansion ve- locity ranges from 4.3 to 7.4 km s−1.
    [Show full text]
  • Structure Analysis of the Perseus and the Cepheus B Molecular Clouds
    Structure analysis of the Perseus and the Cepheus B molecular clouds Inaugural-Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakult¨at der Universit¨at zu K¨oln vorgelegt von Kefeng Sun aus VR China Koln,¨ 2008 Berichterstatter : Prof. Dr. J¨urgen Stutzki Prof. Dr. Andreas Zilges Tag der letzten m¨undlichen Pr¨ufung : 26.06.2008 To my parents and Jiayu Contents Abstract i Zusammenfassung v 1 Introduction 1 1.1 Overviewoftheinterstellarmedium . 1 1.1.1 Historicalstudiesoftheinterstellarmedium . .. 1 1.1.2 ThephasesoftheISM .. .. .. .. .. 2 1.1.3 Carbonmonoxidemolecularclouds . 3 1.2 DiagnosticsofturbulenceinthedenseISM . 4 1.2.1 The ∆-variancemethod.. .. .. .. .. 6 1.2.2 Gaussclumps ........................ 8 1.3 Photondominatedregions . 9 1.3.1 PDRmodels ........................ 12 1.4 Outline ............................... 12 2 Previous studies 14 2.1 ThePerseusmolecularcloud . 14 2.2 TheCepheusBmolecularcloud . 16 3 Large scale low -J CO survey of the Perseus cloud 18 3.1 Observations ............................ 18 3.2 DataSets .............................. 21 3.2.1 Integratedintensitymaps. 21 3.2.2 Velocitystructure. 24 3.3 The ∆-varianceanalysis. 24 3.3.1 Integratedintensitymaps. 27 3.3.2 Velocitychannelmaps . 30 3.4 Discussion.............................. 34 3.4.1 Integratedintensitymaps. 34 3.4.2 Velocitychannelmaps . 34 I II CONTENTS 3.5 Summary .............................. 38 4 The Gaussclumps analysis in the Perseus cloud 40 4.1 Resultsanddiscussions . 40 4.1.1 Clumpmass......................... 41 4.1.2 Clumpmassspectra . 42 4.1.3 Relationsofclumpsizewithlinewidthandmass . 46 4.1.4 Equilibriumstateoftheclumps . 49 4.2 Summary .............................. 53 5 Study of the photon dominated region in the IC 348 cloud 55 5.1 Datasets............................... 56 5.1.1 [C I] and 12CO4–3observationswithKOSMA . 56 5.1.2 Complementarydatasets.
    [Show full text]
  • The Origin of Nonradiative Heating/Momentum in Hot Stars
    NASA Conference Publication 2358 NASA-CP-2358 19850009446 The Origin of Nonradiative Heating/Momentum in Hot Stars Proceedings of a workshop held at NASA Goddard Space Flight Center Greenbelt, Maryland June 5-7, 1984 NI_SA NASA Conference Publication 2358 The Origin of Nonradiative Heating/Momentum in Hot Stars Edited by A. B. Underhill and A. G. Michalitsianos Goddard Space Flight Center Greenbelt, Maryland Proceedings of a workshop sponsored by the National Aeronautics and Space Administration, Washington, D.C., and the American Astronomical Society, Washington, D.C., and held at NASA Goddard Space Flight Center Greenbelt, Maryland June 5-7, 1984 N/LS/X NationalAeronautics and SpaceAdministration ScientificandTechnical InformationBranch J 1985 TABLE OF CONTENTS ORGANIZING COMMITTEE v LIST OF PARTICIPANTS vi OPENING REMARKS A.B. Underhill I SESSION I. - EVIDENCE FOR NONRADIATIVE ACTIVITY IN STARS EVIDENCE FOR NONRADIATIVE ACTIVITY IN HOT STARS J.P. Cassinelli (Invited review) 2 EVIDENCE FOR NON-RADIATIVE ACTIVITY IN STARS WITH Tef f < i0,000 K Jeffrey L. Linsky (Invited review) 24 OBSERVATIONS OF NONTHERMAL RADIO EMISSION FROM EARLY TYPE STARS D.C. Abbott, J.H. Bieging and E. Churehwell 47 NONRADIAL PULSATION AND MASS LOSS IN EARLY B STARS G. Donald Penrod and Myron A. Smith 53 NARROW ABSORPTION COMPONENTS IN Be STAR WINDS C.A. Grady 57 LIGHT VARIATIONS OF THE B-TYPE STAR HD 160202 Gustav A. Bakos 62 ULTRAVIOLET SPECTRAL MORPHOLOGY OF 0-TYPE STELLAR WINDS Nolan R. Walborn 66 NONTHERMAL RADIO EMISSION AND THE HR DIAGRAM D.M. Gibson 70 X-RAY ACTIVITY IN PRE-MAIN SEQUENCE STARS Eric D. Feigelson 75 ACTIVE PHENOMENA IN THE PRE-MAIN SEQUENCE STAR AB AUR F.
    [Show full text]
  • Abstracts of Talks 1
    Abstracts of Talks 1 INVITED AND CONTRIBUTED TALKS (in order of presentation) Milky Way and Magellanic Cloud Surveys for Planetary Nebulae Quentin A. Parker, Macquarie University I will review current major progress in PN surveys in our own Galaxy and the Magellanic clouds whilst giving relevant historical context and background. The recent on-line availability of large-scale wide-field surveys of the Galaxy in several optical and near/mid-infrared passbands has provided unprecedented opportunities to refine selection techniques and eliminate contaminants. This has been coupled with surveys offering improved sensitivity and resolution, permitting more extreme ends of the PN luminosity function to be explored while probing hitherto underrepresented evolutionary states. Known PN in our Galaxy and LMC have been significantly increased over the last few years due primarily to the advent of narrow-band imaging in important nebula lines such as H-alpha, [OIII] and [SIII]. These PNe are generally of lower surface brightness, larger angular extent, in more obscured regions and in later stages of evolution than those in most previous surveys. A more representative PN population for in-depth study is now available, particularly in the LMC where the known distance adds considerable utility for derived PN parameters. Future prospects for Galactic and LMC PN research are briefly highlighted. Local Group Surveys for Planetary Nebulae Laura Magrini, INAF, Osservatorio Astrofisico di Arcetri The Local Group (LG) represents the best environment to study in detail the PN population in a large number of morphological types of galaxies. The closeness of the LG galaxies allows us to investigate the faintest side of the PN luminosity function and to detect PNe also in the less luminous galaxies, the dwarf galaxies, where a small number of them is expected.
    [Show full text]
  • Arxiv:2105.09338V2 [Astro-Ph.GA] 16 Jun 2021
    Draft version June 18, 2021 Typeset using LATEX twocolumn style in AASTeX63 Stars with Photometrically Young Gaia Luminosities Around the Solar System (SPYGLASS) I: Mapping Young Stellar Structures and their Star Formation Histories Ronan Kerr,1 Aaron C. Rizzuto,1, ∗ Adam L. Kraus,1 and Stella S. R. Offner1 1Department of Astronomy, University of Texas at Austin 2515 Speedway, Stop C1400 Austin, Texas, USA 78712-1205 (Accepted May 16, 2021) ABSTRACT Young stellar associations hold a star formation record that can persist for millions of years, revealing the progression of star formation long after the dispersal of the natal cloud. To identify nearby young stellar populations that trace this progression, we have designed a comprehensive framework for the identification of young stars, and use it to identify ∼3×104 candidate young stars within a distance of 333 pc using Gaia DR2. Applying the HDBSCAN clustering algorithm to this sample, we identify 27 top-level groups, nearly half of which have little to no presence in previous literature. Ten of these groups have visible substructure, including notable young associations such as Orion, Perseus, Taurus, and Sco-Cen. We provide a complete subclustering analysis on all groups with substructure, using age estimates to reveal each region's star formation history. The patterns we reveal include an apparent star formation origin for Sco-Cen along a semicircular arc, as well as clear evidence for sequential star formation moving away from that arc with a propagation speed of ∼4 km s−1 (∼4 pc Myr−1). We also identify earlier bursts of star formation in Perseus and Taurus that predate current, kinematically identical active star-forming events, suggesting that the mechanisms that collect gas can spark multiple generations of star formation, punctuated by gas dispersal and cloud regrowth.
    [Show full text]
  • Irradiated Shocks in the W28 A2 Outflow
    Irradiated shocks in the W28 A2 outflow Antoine Gusdorf, LERMA/LRA, Paris, France Maryvonne Gerin, LERMA/LRA, Paris, France Pierre Lesaffre, LERMA/LRA, Paris, France Javier Goicoechea, Centro de Astrobiología (CSIC/INTA), Madrid, Spain Nicolas Flagey, JPL, Pasadena, USA …and the PRISMAS Team 10/16/13 The Universe explored by Herschel, ESA/ESTEC, Noordwijk, The Netherlands, 15-18 October, 2013 1 What is the W28 A2 outflow ? Also known as “G5.89-00.39”, or the “Harvey & Forveille 1988” outflow Hunter et al. 2008 CO (1-0) 20 to 58 km s-1 CO (1-0) 0 to -37 km s-1 10/16/13 The Universe explored by Herschel, ESA/ESTEC, Noordwijk, The Netherlands, 15-18 October, 2013 2 Outline • MOTIVATIONS • THE STRUCTURE OF THE W28A2 REGION • CO OBSERVATIONS • C I & C+ OBSERVATIONS • PERSPECTIVES 10/16/13 The Universe explored by Herschel, ESA/ESTEC, Noordwijk, The Netherlands, 15-18 October, 2013 3 MOTIVATIONS 10/16/13 The Universe explored by Herschel, ESA/ESTEC, Noordwijk, The Netherlands, 15-18 October, 2013 4 Motivations: ISM & massive star formation • The massive star formation problem: How to form massive stars despite the radiation pressure ? . turbulent core model with a monolithic collapse scenario, scale-up of the low-mass scenario . highly dynamical competitive accretion model involving the formation of a cluster • The ISM insights: . Physical and chemical processes in a shocked environment . The shock is irradiated ; What is its environmental impact ? 10/16/13 The Universe explored by Herschel, ESA/ESTEC, Noordwijk, The Netherlands, 15-18 October, 2013 5 Motivations: the energetic balance of galaxies • CO ladders observations from external galaxies Large scale effects from PDR, XDR, and shock contributions NGC 253 Hailey-Dunsheath et al.
    [Show full text]