Ossenkopf, V. and Lord, S. and Phillips, T. (2010) HIFI observations of warm gas in DR21: Shock versus radiative heating. Astronomy and Astrophysics, 518 . L79. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20101116-100230331
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Context. The molecular gas in the DR21 massive star formation region is known to be affected by the strong UV field from the central star cluster and by a fast outflow creating a bright shock. The relative contribution of both heating mechanisms is the matter of a long debate. Aims. By better sampling the excitation ladder of various tracers we provide a quantitative distinction between the different heating mechanisms. Methods. HIFI observations of mid-J transitions of CO and HCO^+ isotopes allow us to bridge the gap in excitation energies between observations from the ground, characterizing the cooler gas, and existing ISO LWS spectra, constraining the properties of the hot gas. Comparing the detailed line profiles allows to identify the physical structure of the different components. Results. In spite of the known shock-excitation of H_2 and the clearly visible strong outflow, we find that the emission of all lines up to ≳2 THz can be explained by purely radiative heating of the material. However, the new Herschel/HIFI observations reveal two types of excitation conditions. We find hot and dense clumps close to the central cluster, probably dynamically affected by the outflow, and a more widespread distribution of cooler, but nevertheless dense, molecular clumps.
|Additional Information:||© 2010 ESO. Received 30 March 2010; Accepted 20 April 2010; Published online 16 July 2010. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada and the United States under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands and with major contributions from Germany, France and the US. Consortium members are: Canada: CSA, U. Waterloo; France: CESR, LAB, LERMA, IRAM; Germany: KOSMA, MPIfR, MPS; Ireland: NUI Maynooth; Italy: ASI, IFSI-INAF, Osservatorio Astrofisico di Arcetri- INAF; Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronmico Nacional (IGN), Centro de Astrobiología (CSIC-INTA). Sweden: Chalmers University of Technology – MC2, RSS & GARD; Onsala Space Observatory; Swedish National Space Board, Stockholm University – Stockholm Observatory; Switzerland: ETH Zurich, FHNW; USA: Caltech, JPL, NHSC. This work was supported by the German Deutsche Forschungsgemeinschaft, DFG project number Os 177/1–1. A portion of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.|
|Subject Keywords:||ISM: structure; ISM: kinematics and dynamics; ISM: molecules; HII regions; submillimeter: ISM|
|Official Citation:||HIFI observations of warm gas in DR21: Shock versus radiative heating V. Ossenkopf, M. Röllig, R. Simon, N. Schneider, Y. Okada, J. Stutzki, M. Gerin, M. Akyilmaz, D. Beintema, A. O. Benz, O. Berne, F. Boulanger, B. Bumble, O. Coeur-Joly, C. Dedes, M. C. Diez-Gonzalez, K. France, A. Fuente, J. D. Gallego, J. R. Goicoechea, R. Güsten, A. Harris, R. Higgins, B. Jackson, C. Jarchow, C. Joblin, T. Klein, C. Kramer, S. Lord, P. Martin, J. Martin-Pintado, B. Mookerjea, D. A. Neufeld, T. Phillips, J. R. Rizzo, F. F. S. van der Tak, D. Teyssier and H. Yorke A&A 518 L79 (2010) DOI: 10.1051/0004-6361/201014579|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||16 Nov 2010 19:22|
|Last Modified:||26 Dec 2012 12:38|
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