Interstellar OH+, H2O+ and H3O+ along the sight-line to G10.6-0.4
Journal article, 2010
We report the detection of absorption lines by the reactive ions OH+, H2O+ and H3O+ along the line of sight to the submillimeter continuum source G10.6$-$0.4 (W31C). We used the Herschel HIFI instrument in dual beam switch mode to observe the ground state rotational transitions of OH+ at 971 GHz, H2O+ at 1115 and 607 GHz, and H3O+ at 984 GHz. The resultant spectra show deep absorption over a broad velocity range that originates in the interstellar matter along the line of sight to G10.6$-$0.4 as well as in the molecular gas directly associated with that source. The OH+ spectrum reaches saturation over most velocities corresponding to the foreground gas, while the opacity of the H2O+ lines remains lower than 1 in the same velocity range, and the H3O+ line shows only weak absorption. For LSR velocities between 7 and 50 kms$^{-1}$ we estimate total column densities of $N$(OH+) $> 2.5 \times 10^{14}$ cm$^{-2}$, $N$(H2O+) $\sim 6 \times 10^{13}$ cm$^{-2}$ and $N$(H3O+) $\sim 4.0 \times 10^{13}$ cm$^{-2}$. These detections confirm the role of O$^+$ and OH$^+$ in initiating the oxygen chemistry in diffuse molecular gas and strengthen our understanding of the gas phase production of water. The high ratio of the OH+ by the H2O+ column density implies that these species predominantly trace low-density gas with a small fraction of hydrogen in molecular form.
ISM: molecules
ISM: clouds
ISM: general
Author
M. Gerin
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
M. de Luca
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
John H Black
Chalmers, Department of Radio and Space Science, Radio Astronomy and Astrophysics
J.R. Goicoechea
Centro de Astrobiologia (CAB)
E. Herbst
Ohio State University
D.A. Neufeld
Johns Hopkins University
E. Falgarone
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
B. Godard
Institut d'Astrophysique Spatiale
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
T. J. Pearson
Jet Propulsion Laboratory, California Institute of Technology
D. Lis
California Institute of Technology (Caltech)
T.G. Phillips
California Institute of Technology (Caltech)
T. A. Bell
California Institute of Technology (Caltech)
P. Sonnentrucker
Johns Hopkins University
F. Boulanger
Institut d'Astrophysique Spatiale
J. Cernicharo
Centro de Astrobiologia (CAB)
A. Coutens
Centre national de la recherche scientifique (CNRS)
University of Toulouse
E. Dartois
Institut d'Astrophysique Spatiale
P. Encrenaz
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
T. Giesen
University of Cologne
P.F. Goldsmith
Jet Propulsion Laboratory, California Institute of Technology
H. Gupta
Jet Propulsion Laboratory, California Institute of Technology
C. Gry
Laboratoire d'Astrophysique de Marseille
P. Hennebelle
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
P. Hily-Blant
Laboratoire d'Astrophysique de Grenoble
C. Joblin
Centre national de la recherche scientifique (CNRS)
University of Toulouse
M. Kazmierczak
Nicolaus Copernicus University
R. Kolos
Polish Academy of Sciences
J. Krelowski
Nicolaus Copernicus University
J. Martin-Pintado
Centro de Astrobiologia (CAB)
Raquel Monje
Chalmers, Department of Radio and Space Science, Advanced Receiver Development
B. Mookerjea
Tata Institute of Fundamental Research
M. Perault
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
Carina Persson
Chalmers, Department of Radio and Space Science, Radio Astronomy and Astrophysics
R. Plume
University of Calgary
P. B. Rimmer
Ohio State University
M Salez
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
M. Schmidt
European Space Astronomy Centre (ESAC)
J. Stutzki
University of Cologne
D. Teyssier
MPI fur Extraterrestrische Physik
C. Vastel
Centre national de la recherche scientifique (CNRS)
University of Toulouse
S. Yu
Jet Propulsion Laboratory, California Institute of Technology
A. Contursi
Max Planck Society
K. Menten
Gemini Observatory North
Thomas Geballe
Polish Academy of Sciences
S. Schlemmer
University of Cologne
R. Shipman
Netherlands Institute for Space Research (SRON)
A.G.G.M. Tielens
S. Philipp-May
German Aerospace Center (DLR)
Gemini Observatory North
A. Cros
Centre national de la recherche scientifique (CNRS)
University of Toulouse
J. Zmuidzinas
California Institute of Technology (Caltech)
L.A. Samoska
Jet Propulsion Laboratory, California Institute of Technology
K. Klein
German Aerospace Center (DLR)
A. Lorenzani
Arcetri Astrophysical Observatory
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 518 4 110- L110Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201014576