Monje, R. R. and Emprechtinger, M. and Phillips, T. G. and Lis, D. C. and Goldsmith, P. F. and Bergin, E. A. and Bell, T. A. and Neufeld, D. A. and Sonnentrucker, P. (2011) Herschel/HIFI Observations of Hydrogen Fluoride Toward Sagittarius B2(M). Astrophysical Journal Letters, 734 (1). Art. No. L23. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20110901-154343912
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Herschel/HIFI observations have revealed the presence of widespread absorption by hydrogen fluoride (HF) J = 1-0 rotational transition, toward a number of Galactic sources. We present observations of HF J = 1-0 toward the high-mass star-forming region Sagittarius B2(M). The spectrum obtained shows a complex pattern of absorption, with numerous features covering a wide range of local standard of rest velocities (–130 to 100 km^(–1)). An analysis of this absorption yields HF abundances relative to H_2 of ~1.3 × 10^(–8), in most velocity intervals. This result is in good agreement with estimates from chemical models, which predict that HF should be the main reservoir of gas-phase fluorine under a wide variety of interstellar conditions. Interestingly, we also find velocity intervals in which the HF spectrum shows strong absorption features that are not present, or are very weak, in spectra of other molecules, such as ^(13)CO (1-0) and CS (2-1). HF absorption reveals components of diffuse clouds with small extinction that can be studied for the first time. Another interesting observation is that water is significantly more abundant than hydrogen fluoride over a wide range of velocities toward Sagittarius B2(M), in contrast to the remarkably constant H_2O/HF abundance ratio with average value close to unity measured toward other Galactic sources.
|Additional Information:||© 2011 The American Astronomical Society. Received 2011 April 12; accepted 2011 May 9; published 2011 May 20. We thank the referee Dr. Andrew Walsh for his helpful comments and suggestions. 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; The Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronomico 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. Support for this work was provided by NASA through an award issued by JPL/Caltech. This research has been supported in part by the NSF, award AST-0540882 to the CSO. 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. Facilities: Herschel, IRAM:30m|
|Subject Keywords:||Galaxy: abundances; ISM: abundances; ISM: individual objects (Sagittarius B2)|
|Classification Code:||PACS: 98.38.Dq; 98.35.Jk; 98.38.Bn; 95.85.Fm|
|Official Citation:||Herschel/HIFI Observations of Hydrogen Fluoride Toward Sagittarius B2(M) R. R. Monje et al. 2011 ApJ 734 L23|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||02 Sep 2011 19:11|
|Last Modified:||26 Dec 2012 13:39|
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