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Variations in H_2O^+/H_2O ratios toward massive star-forming regions

Wyrowski, F. and Blake, G. and Lis, D. (2010) Variations in H_2O^+/H_2O ratios toward massive star-forming regions. Astronomy and Astrophysics, 521 . Art. No. L34. ISSN 0004-6361.

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Early results from the Herschel Space Observatory revealed the water cation H_2O^+ to be an abundant ingredient of the interstellar medium. Here we present new observations of the H_2O and H_2O^+ lines at 1113.3 and 1115.2 GHz using the Herschel Space Observatory toward a sample of high-mass star-forming regions to observationally study the relation between H_2O and H_2O^+. Nine out of ten sources show absorption from H_2O^+ in a range of environments: the molecular clumps surrounding the forming and newly formed massive stars, bright high-velocity outflows associated with the massive protostars, and unrelated low-density clouds along the line of sight. Column densities per velocity component of H_2O^+ are found in the range of 10^(12) to a few 10^(13) cm^(−2). The highest N(H_2O^+) column densities are found in the outflows of the sources. The ratios of H_2O^+/H_2O are determined in a range from 0.01 to a few and are found to differ strongly between the observed environments with much lower ratios in the massive (proto)cluster envelopes (0.01−0.1) than in outflows and diffuse clouds. Remarkably, even for source components detected in H_2O in emission, H_2O^+ is still seen in absorption.

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Blake, G.0000-0003-0787-1610
Lis, D.0000-0002-0500-4700
Additional Information:© 2010 ESO. Received 31 May 2010, Accepted 19 July 2010, Published online 01 October 2010. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. The XCLASS program (http://www.astro. was used, which accesses the CDMS ( and JPL (http://spec.jpl.nasa. gov) molecular data bases. 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 Astronomico Nacional (IGN), Centro de Astrobiologia (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. HCSS/HSpot/HIPE is a joint development (are joint developments) by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS and SPIRE consortia. We would like to thank the referee, Christian Henkel, for a thorough review of the manuscript and helpful comments.
Subject Keywords:ISM: clouds – ISM: molecules – submillimeter: ISM – stars: formation
Record Number:CaltechAUTHORS:20110110-140108665
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Official Citation:Variations in H2O+/H2O ratios toward massive star-forming regions F. Wyrowski, F. van der Tak, F. Herpin, A. Baudry, S. Bontemps, L. Chavarria, W. Frieswijk, T. Jacq, M. Marseille, R. Shipman, E. F van Dishoeck, A. O. Benz, P. Caselli, M. R. Hogerheijde, D. Johnstone, R. Liseau, R. Bachiller, M. Benedettini, E. Bergin, P. Bjerkeli, G. Blake, J. Braine, S. Bruderer, J. Cernicharo, C. Codella, F. Daniel, A. M. di Giorgio, C. Dominik, S. D. Doty, P. Encrenaz, M. Fich, A. Fuente, T. Giannini, J. R. Goicoechea, Th. de Graauw, F. Helmich, G. J. Herczeg, J. K. Jørgensen, L. E. Kristensen, B. Larsson, D. Lis, C. McCoey, G. Melnick, B. Nisini, M. Olberg, B. Parise, J. C. Pearson, R. Plume, C. Risacher, J. Santiago, P. Saraceno, M. Tafalla, T. A. van Kempen, R. Visser, S. Wampfler, U. A. Yıldız, J. H. Black, E. Falgarone, M. Gerin, P. Roelfsema, P. Dieleman, D. Beintema, A. De Jonge, N. Whyborn, J. Stutzki and V. Ossenkopf A&A 521 L34 (2010) DOI: 10.1051/0004-6361/201015110
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21673
Deposited By: Benjamin Perez
Deposited On:10 Jan 2011 22:30
Last Modified:03 Oct 2019 02:27

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