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: molecules

cn

h-2

objects: W51

ISM: individual

star-forming regions

submillimeter: ISM

molecular absorption

comparative chemistry

ISM: individual objects: W49N

ISM: clouds

objects: G10.6-0.4

ISM: individual

clouds

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

CalTech

A. Coutens

Centre national de la recherche scientifique (CNRS)

Université de Toulouse

M. Kazmierczak

Uniwersytet Mikołaja Kopernika w Toruniu

P. Sonnentrucker

Johns Hopkins University

John H Black

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

D. A. Neufeld

Johns Hopkins University

T. G. Phillips

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

CalTech

C. Vastel

Centre national de la recherche scientifique (CNRS)

Université de Toulouse

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

Institute of Physical Chemistry of the Polish Academy of Sciences

J. Krelowski

Uniwersytet Mikołaja Kopernika w Toruniu

J. Martin-Pintado

Centro de Astrobiologia (CAB)

Raquel Rodriguez-Monje

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

Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences

J. Stutzki

Universität zu Köln

D. Teyssier

European Space Astronomy Centre (ESA)

S. Yu

Jet Propulsion Laboratory, California Institute of Technology

A. Contursi

MPI fur Extraterrestrische Physik

K. Menten

Max Planck-institutet

T. R. Geballe

Gemini Telescope

S. Schlemmer

Universität zu Köln

P. Morris

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

Centre national de la recherche scientifique (CNRS)

Université de Toulouse

R. Güsten

Max Planck-institutet

T. Klein

Max Planck-institutet

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

CalTech

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 521 1 Article Number: L16- L16

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/201015115