Interstellar CH absorption in the diffuse interstellar medium along the sight-lines to G10.6-0.4 (W31C), W49N, and W51
Artikel i vetenskaplig tidskrift, 2010
We report the detection of the ground state N, J = 1, 3/2 -> 1, 1/2 doublet of the methylidyne radical CH at similar to 532 GHz and similar to 536 GHz with the Herschel/ HIFI instrument along the sight-line to the massive star-forming regions G10.6-0.4 (W31C), W49N, and W51. While the molecular cores associated with these massive star-forming regions show emission lines, clouds in the diffuse interstellar medium are detected in absorption against the strong submillimeter background. The combination of hyperfine structure with emission and absorption results in complex profiles, with overlap of the different hyperfine components. The opacities of most of the CH absorption features are linearly correlated with those of CCH, CN, and HCO+ in the same velocity intervals. In specific narrow velocity intervals, the opacities of CN and HCO+ deviate from the mean trends, giving rise to more opaque absorption features. We propose that CCH can be used as another tracer of the molecular gas in the absence of better tracers, with [CCH]/[H2] similar to 3.2 +/- 1.1 x 10-8. The observed [CN]/[CH], [CCH]/[CH] abundance ratios suggest that the bulk of the diffuse matter along the lines of sight has gas densities nH = n(H) + 2n(H2) ranging between 100 and 1000 cm-3).
ISM: individual
molecular absorption
cn
ISM: individual objects: W49N
submillimeter: ISM
objects: W51
objects: G10.6-0.4
ISM: molecules
ISM: individual
clouds
comparative chemistry
h-2
ISM: clouds
star-forming regions
Författare
M. Gerin
Ecole Normale Superieure (ENS)
M. de Luca
Ecole Normale Superieure (ENS)
J. R. Goicoechea
Centro de Astrobiologia (CAB)
E. Herbst
Ohio State University
E. Falgarone
Ecole Normale Superieure (ENS)
B. Godard
Ecole Normale Superieure (ENS)
Institut d'Astrophysique Spatiale
T. A. Bell
California Institute of Technology (Caltech)
A. Coutens
Centre national de la recherche scientifique (CNRS)
Université de Toulouse
M. Kazmierczak
Uniwersytet Mikolaja Kopernika
P. Sonnentrucker
Johns Hopkins University
John H Black
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
D. A. Neufeld
Johns Hopkins University
T. G. Phillips
California Institute of Technology (Caltech)
J. C. Pearson
Jet Propulsion Laboratory, California Institute of Technology
P. B. Rimmer
Ohio State University
G.E. Hassel
Ohio State University
D. C. Lis
California Institute of Technology (Caltech)
C. Vastel
Université de Toulouse
Centre national de la recherche scientifique (CNRS)
F. Boulanger
Institut d'Astrophysique Spatiale
J. Cernicharo
Centro de Astrobiologia (CAB)
E. Dartois
Institut d'Astrophysique Spatiale
P. Encrenaz
Ecole Normale Superieure (ENS)
T. Giesen
Universität zu Köln
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
Ecole Normale Superieure (ENS)
P. Hily-Blant
Laboratoire d'Astrophysique de Grenoble
C. Joblin
Université de Toulouse
Centre national de la recherche scientifique (CNRS)
R. Kolos
Polish Academy of Sciences
J. Krelowski
Uniwersytet Mikolaja Kopernika
J. Martin-Pintado
Centro de Astrobiologia (CAB)
Raquel Monje
California Institute of Technology (Caltech)
B. Mookerjea
Tata Institute of Fundamental Research
M. Perault
Ecole Normale Superieure (ENS)
Carina Persson
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
R. Plume
University of Calgary
M. Salez
Ecole Normale Superieure (ENS)
M. Schmidt
Polish Academy of Sciences
J. Stutzki
Universität zu Köln
D. Teyssier
European Space Astronomy Centre (ESAC)
S. Yu
Jet Propulsion Laboratory, California Institute of Technology
A. Contursi
MPI fur Extraterrestrische Physik
K. Menten
Max-Planck-Gesellschaft
T. R. Geballe
Gemini Observatory North
S. Schlemmer
Universität zu Köln
P. Morris
California Institute of Technology (Caltech)
W. A. Hatch
Jet Propulsion Laboratory, California Institute of Technology
M. Imram
Jet Propulsion Laboratory, California Institute of Technology
J. S. Ward
Jet Propulsion Laboratory, California Institute of Technology
E. Caux
Université de Toulouse
Centre national de la recherche scientifique (CNRS)
R. Güsten
Max-Planck-Gesellschaft
T. Klein
Max-Planck-Gesellschaft
P. Roelfsema
Netherlands Institute for Space Research (SRON)
P. Dieleman
Netherlands Institute for Space Research (SRON)
R. Schieder
Universität zu Köln
N. Honingh
Universität zu Köln
J. Zmuidzinas
California Institute of Technology (Caltech)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 521 1 Article Number: L16- L16Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.1051/0004-6361/201015115