Universität zu Köln

Sonnentrucker, P., Neufeld, D. A., Phillips, T. G., Gerin, M., Lis, D. C., De Luca, M., Goicoechea, J. R., Black, J. H., Bell, T. A., Boulanger, F., Cernicharo, J., Coutens, A., Dartois, E., Kazmierczak, M., Encrenaz, P., Falgarone, E., Geballe, T. R., Giesen, T., Godard, B., Goldsmith, P. F., Gry, C., Gupta, H., Hennebelle, P., Herbst, E., Hily-Blant, P., Joblin, C., Kolos, R., Krelowski, J., Martin-Pintado, J., Menten, K. M., Monje, R., Mookerjea, B., Pearson, J., Perault, M., Persson, C. M., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Stutzki, J., Teyssier, D., Vastel, C., Yu, S., Caux, E., Guesten, R., Hatch, W. A., Klein, T., Mehdi, I., Morris, P. and Ward, J. S. (2010). Detection of hydrogen fluoride absorption in diffuse molecular clouds with Herschel/HIFI: an ubiquitous tracer of molecular gas. Astron. Astrophys., 521. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 0004-6361

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Abstract

We discuss the detection of absorption by interstellar hydrogen fluoride (HF) along the sight line to the submillimeter continuum sources W49N and W51. We have used Herschel's HIFI instrument in dual beam switch mode to observe the 1232.4762 GHz J = 1-0 HF transition in the upper sideband of the band 5a receiver. We detected foreground absorption by HF toward both sources over a wide range of velocities. Optically thin absorption components were detected on both sight lines, allowing us to measure - as opposed to obtain a lower limit on - the column density of HF for the first time. As in previous observations of HF toward the source G10.6-0.4, the derived HF column density is typically comparable to that of water vapor, even though the elemental abundance of oxygen is greater than that of fluorine by four orders of magnitude. We used the rather uncertain N(CH) - N(H-2) relationship derived previously toward diffuse molecular clouds to infer the molecular hydrogen column density in the clouds exhibiting HF absorption. Within the uncertainties, we find that the abundance of HF with respect to H-2 is consistent with the theoretical prediction that HF is the main reservoir of gas-phase fluorine for these clouds. Thus, hydrogen fluoride has the potential to become an excellent tracer of molecular hydrogen, and provides a sensitive probe of clouds of small H-2 column density. Indeed, the observations of hydrogen fluoride reported here reveal the presence of a low column density diffuse molecular cloud along the W51 sight line, at an LSR velocity of similar to 24 km s(-1), that had not been identified in molecular absorption line studies prior to the launch of Herschel.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Sonnentrucker, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Neufeld, D. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Phillips, T. G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gerin, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lis, D. C. UNSPECIFIED UNSPECIFIED UNSPECIFIED De Luca, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Goicoechea, J. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Black, J. H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bell, T. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Boulanger, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Cernicharo, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Coutens, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Dartois, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kazmierczak, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Encrenaz, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Falgarone, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Geballe, T. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Giesen, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Godard, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Goldsmith, P. F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gry, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gupta, H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hennebelle, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Herbst, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hily-Blant, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Joblin, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Kolos, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Krelowski, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Martin-Pintado, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Menten, K. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Monje, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mookerjea, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Pearson, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Perault, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Persson, C. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Plume, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Salez, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schlemmer, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmidt, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Stutzki, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Teyssier, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Vastel, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Yu, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Caux, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Guesten, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hatch, W. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Klein, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mehdi, I. UNSPECIFIED UNSPECIFIED UNSPECIFIED Morris, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ward, J. S. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-495055
DOI:	10.1051/0004-6361/201015082
Journal or Publication Title:	Astron. Astrophys.
Volume:	521
Date:	2010
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	0004-6361
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language STAR-FORMING REGIONS; LINE-OF-SIGHT; G10.6-0.4 W31C; W51; W49N; ASTRONOMY; ABUNDANCE; H2O; CO Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/49505