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Herschel observations of EXtra-Ordinary Sources (HEXOS): Observations of H_2O and its isotopologues towards Orion KL

Melnick, G. J. and Phillips, T. G. and Bell, T. A. and Blake, G. A. and Emprechtinger, M. and Joblin, C. and Latter, W. D. and Lis, D. C. and Lord, S. D. and Morris, P. and Zmuidzinas, J. (2010) Herschel observations of EXtra-Ordinary Sources (HEXOS): Observations of H_2O and its isotopologues towards Orion KL. Astronomy and Astrophysics, 521 . Art. No. L27. ISSN 0004-6361.

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We report the detection of more than 48 velocity-resolved ground rotational state transitions of H^(16)_2O, H^(18) _2O, and ^(17)_2O – most for the first time – in both emission and absorption toward Orion KL using Herschel/HIFI. We show that a simple fit, constrained to match the known emission and absorption components along the line of sight, is in excellent agreement with the spectral profiles of all the water lines. Using the measured H^(18)_2O line fluxes, which are less affected by line opacity than their H^(16)_2O counterparts, and an escape probability method, the column densities of H^(18)_2O associated with each emission component are derived. We infer total water abundances of 7.4 × 10^(−5), 1.0 × 10^(−5), and 1.6 × 10^(−5) for the plateau, hot core, and extended warm gas, respectively. In the case of the plateau, this value is consistent with previous measures of the Orion-KL water abundance as well as those of other molecular outflows. In the case of the hot core and extended warm gas, these values are somewhat higher than water abundances derived for other quiescent clouds, suggesting that these regions are likely experiencing enhanced water-ice sublimation from (and reduced freeze-out onto) grain surfaces due to the warmer dust in these sources.

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Blake, G. A.0000-0003-0787-1610
Lis, D. C.0000-0002-0500-4700
Additional Information:© 2010 ESO. Received 30 May 2010, Accepted 12 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. Table 3 (page 5) is only available in electronic form at 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 Astronómico 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. Support for this work was provided by NASA through an award issued by JPL/Caltech. CSO is supported by the NSF, award AST-0540882.
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Subject Keywords:ISM: abundances – ISM: molecules
Record Number:CaltechAUTHORS:20101230-104156323
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Official Citation:Herschel observations of EXtra-Ordinary Sources (HEXOS): Observations of H2O and its isotopologues towards Orion KL G. J. Melnick, V. Tolls, D. A. Neufeld, E. A. Bergin, T. G. Phillips, S. Wang, N. R. Crockett, T. A. Bell, G. A. Blake, S. Cabrit, E. Caux, C. Ceccarelli, J. Cernicharo, C. Comito, F. Daniel, M.-L. Dubernet, M. Emprechtinger, P. Encrenaz, E. Falgarone, M. Gerin, T. F. Giesen, J. R. Goicoechea, P. F. Goldsmith, E. Herbst, C. Joblin, D. Johnstone, W. D. Langer, W. D. Latter, D. C. Lis, S. D. Lord, S. Maret, P. G. Martin, K. M. Menten, P. Morris, H. S. P. Müller, J. A. Murphy, V. Ossenkopf, L. Pagani, J. C. Pearson, M. Pérault, R. Plume, S.-L. Qin, M. Salez, P. Schilke, S. Schlemmer, J. Stutzki, N. Trappe, F. F. S. van der Tak, C. Vastel, H. W. Yorke, S. Yu and J. Zmuidzinas A&A 521 L27 (2010) DOI: 10.1051/0004-6361/201015085
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21523
Deposited By: Benjamin Perez
Deposited On:03 Jan 2011 17:09
Last Modified:31 Aug 2017 02:49

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