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Water abundance variations around high-mass protostars: HIFI observations of the DR21 region

van der Tak, F. F. S. and Blake, G. and Lis, D. (2010) Water abundance variations around high-mass protostars: HIFI observations of the DR21 region. Astronomy and Astrophysics, 518 . L107. ISSN 0004-6361.

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Context. Water is a key molecule in the star formation process, but its spatial distribution in star-forming regions is not well known. Aims. We study the distribution of dust continuum and H_(2)O and ^(13)CO line emission in DR21, a luminous star-forming region with a powerful outflow and a compact H ii region. Methods. Herschel-HIFI spectra near 1100 GHz show narrow ^(13)CO 10–9 emission and H_(2)O 1_(11)–0_(00) absorption from the dense core and broad emission from the outflow in both lines. The H_(2)O line also shows absorption by a foreground cloud known from ground-based observations of low-J CO lines. Results. The dust continuum emission is extended over 36” FWHM, while the ^(13)CO and H_(2)O lines are confined to ≈24” or less. The foreground absorption appears to peak further North than the other components. Radiative transfer models indicate very low abundances of ~2×10^(-10) for H_(2)O and ~8×10^(-7) for ^(13)CO in the dense core, and higher H_(2)O abundances of ~4×10^(-9) in the foreground cloud and ~7×10^(-7) in the outflow. Conclusions. The high H_(2)O abundance in the warm outflow is probably due to the evaporation of water-rich icy grain mantles, while the H_(2)O abundance is kept down by freeze-out in the dense core and by photodissociation in the foreground cloud.

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Blake, G.0000-0003-0787-1610
Lis, D.0000-0002-0500-4700
Additional Information:© 2010 ESO. Received 26 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 US under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands 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, Arcetri-INAF; Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronómico 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 Zürich, FHNW; USA: Caltech, JPL, NHSC.
Subject Keywords:ISM: molecules; stars: formation; astrochemistry; ISM: individual objects: DR21
Record Number:CaltechAUTHORS:20101122-095249415
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Official Citation:Water abundance variations around high-mass protostars: HIFI observations of the DR21 region F. F. S. van der Tak, M. G. Marseille, F. Herpin, F. Wyrowski, A. Baudry, S. Bontemps, J. Braine, S. Doty, W. Frieswijk, G. Melnick, R. Shipman, E. F. van Dishoeck, A. O. Benz, P. Caselli, M. Hogerheijde, D. Johnstone, R. Liseau, R. Bachiller, M. Benedettini, E. Bergin, P. Bjerkeli, G. Blake, S. Bruderer, J. Cernicharo, C. Codella, F. Daniel, A. M. di Giorgio, C. Dominik, P. Encrenaz, M. Fich, A. Fuente, T. Giannini, J. Goicoechea, Th. de Graauw, F. Helmich, G. Herczeg, J. Jørgensen, L. Kristensen, B. Larsson, D. Lis, C. McCoey, D. Neufeld, B. Nisini, M. Olberg, B. Parise, J. Pearson, R. Plume, C. Risacher, J. Santiago, P. Saraceno, M. Tafalla, T. van Kempen, R. Visser, S. Wampfler, U. Yıldız, L. Ravera, P. Roelfsema, O. Siebertz and D. Teyssier A&A 518 L107 (2010) DOI: 10.1051/0004-6361/201014515
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20936
Deposited By: Jason Perez
Deposited On:23 Nov 2010 00:15
Last Modified:03 Oct 2019 02:17

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