Neufeld, D. A., Goicoechea, J. R., Sonnentrucker, P., Black, J. H., Pearson, J., Yu, S., Phillips, T. G., Lis, D. C., De Luca, M., Herbst, E., Rimmer, P., Gerin, M., 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., Hily-Blant, P., Joblin, C., Kolos, R., Krclowski, J., Martin-Pintado, J., Menten, K. M., Monje, R., Mookerjea, B., Perault, M., Persson, C., Plume, R., Salez, M., Schlemmer, S., Schmidt, M., Stutzki, J., Teyssier, D., Vastel, C., Cros, A., Klein, K., Lorenzani, A., Philipp, S., Samoska, A., Shipman, R., Tielens, A. G. G. M., Szczerba, R. ORCID: 0000-0003-2886-4460 and Zmuidzinas, J. (2010). Herschel/HIFI observations of interstellar OH+ and H2O+ towards W49N: a probe of diffuse clouds with a small molecular fraction. Astron. Astrophys., 521. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 0004-6361

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Abstract

We report the detection of absorption by interstellar hydroxyl cations and water cations, along the sight-line to the bright continuum source W49N. We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 972 GHz N = 1-0 transition of OH+ and the 1115 GHz 1(11)-0(00) transition of ortho-H2O+. The resultant spectra show absorption by ortho-H2O+, and strong absorption by OH+, in foreground material at velocities in the range 0 to 70 km s(-1) with respect to the local standard of rest. The inferred OH+/H2O+ abundance ratio ranges from similar to 3 to similar to 15, implying that the observed OH+ arises in clouds of small molecular fraction, in the 2-8% range. This conclusion is confirmed by the distribution of OH+ and H2O+ in Doppler velocity space, which is similar to that of atomic hydrogen, as observed by means of 21 cm absorption measurements, and dissimilar from that typical of other molecular tracers. The observed OH+/H abundance ratio of a few x10(-8) suggests a cosmic ray ionization rate for atomic hydrogen of 0.6-2.4 x 10(-16) s(-1), in good agreement with estimates inferred previously for diffuse clouds in the Galactic disk from observations of interstellar H-3(+) and other species.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Neufeld, D. A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Goicoechea, J. R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Sonnentrucker, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Black, J. H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Pearson, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Yu, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Phillips, T. G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lis, D. C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
De Luca, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Herbst, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Rimmer, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gerin, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Bell, T. A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Boulanger, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Cernicharo, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Coutens, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Dartois, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kazmierczak, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Encrenaz, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Falgarone, E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Geballe, T. R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Giesen, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Godard, B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Goldsmith, P. F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gry, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gupta, H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hennebelle, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hily-Blant, P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Joblin, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kolos, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Krclowski, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Martin-Pintado, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Menten, K. M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Monje, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Mookerjea, B.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Perault, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Persson, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Plume, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Salez, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Schlemmer, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Schmidt, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Stutzki, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Teyssier, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Vastel, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Cros, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Klein, K.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Lorenzani, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Philipp, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Samoska, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Shipman, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Tielens, A. G. G. M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Szczerba, R.UNSPECIFIEDorcid.org/0000-0003-2886-4460UNSPECIFIED
Zmuidzinas, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-495002
DOI: 10.1051/0004-6361/201015077
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:
KeywordsLanguage
LASER MAGNETIC-RESONANCE; STAR-FORMING REGIONS; ABSORPTION; GAS; TRACER; H-3(+); CATION; MODEL; LINEMultiple languages
Astronomy & AstrophysicsMultiple languages
URI: http://kups.ub.uni-koeln.de/id/eprint/49500

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