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The Abundance, Ortho/Para Ratio, and Deuteration of Water in the High-mass Star-forming Region NGC 6334 I

Emprechtinger, M. and Lis, D. C. and Rolffs, R. and Schilke, P. and Monje, R. R. and Comito, C. and Ceccarelli, C. and Neufeld, D. A. and van der Tak, F. F. S. (2013) The Abundance, Ortho/Para Ratio, and Deuteration of Water in the High-mass Star-forming Region NGC 6334 I. Astrophysical Journal, 765 (1). Art. No. 61. ISSN 0004-637X. doi:10.1088/0004-637X/765/1/61.

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We present Herschel/HIFI observations of 30 transitions of water isotopologues toward the high-mass star-forming region NGC 6334 I. The line profiles of H^(16)_2O, H^(17)_2O, H^(18)_2O, and HDO show a complex pattern of emission and absorption components associated with the embedded hot cores, a lower-density envelope, two outflow components, and several foreground clouds, some associated with the NGC 6334 complex, others seen in projection against the strong continuum background of the source. Our analysis reveals an H_2O ortho/para ratio of 3 ± 0.5 in the foreground clouds, as well as the outflow. The water abundance varies from ~10^(–8) in the foreground clouds and the outer envelope to ~10^(–6) in the hot core. The hot core abundance is two orders of magnitude below the chemical model predictions for dense, warm gas, but within the range of values found in other Herschel/HIFI studies of hot cores and hot corinos. This may be related to the relatively low gas and dust temperature (~100 K), or time-dependent effects, resulting in a significant fraction of water molecules still locked up in dust grain mantles. The HDO/H_2O ratio in NGC 6334 I, ~2 × 10^(–4), is also relatively low, but within the range found in other high-mass star-forming regions.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Lis, D. C.0000-0002-0500-4700
Schilke, P.0000-0003-2141-5689
Ceccarelli, C.0000-0001-9664-6292
Neufeld, D. A.0000-0001-8341-1646
Additional Information:© 2013 American Astronomical Society. Received 2011 December 15; accepted 2012 December 18; published 2013 February 15. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada, and theUnited 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 Astrobiologa (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, by l’Agence Nationale pour la Recherche (ANR), France (project FORCOMS, contracts ANR-08-BLAN-022), and the Centre National d’Etudes Spatiales (CNES). We thank the anonymous referee for constructive comments that have significantly improved the presentation.
Funding AgencyGrant Number
Agence Nationale pour la Recherche (ANR)ANR-08-BLAN-022
Centre National d’Etudes Spatiales (CNES)UNSPECIFIED
Subject Keywords:ISM: molecules; stars: formation
Issue or Number:1
Record Number:CaltechAUTHORS:20130402-105843744
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Official Citation:The Abundance, Ortho/Para Ratio, and Deuteration of Water in the High-mass Star-forming Region NGC 6334 I M. Emprechtinger et al. 2013 ApJ 765 61
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37721
Deposited By: Ruth Sustaita
Deposited On:02 Apr 2013 18:30
Last Modified:09 Nov 2021 23:30

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