Herschel observations of EXtra-Ordinary Sources (HEXOS): detecting spiral arm clouds by CH absorption lines
Journal article, 2010
We have observed CH absorption lines (J = 3/2, N = 1 <- J = 1/2, N = 1) against the continuum source Sgr B2(M) using the Herschel/HIFI instrument. With the high spectral resolution and wide velocity coverage provided by HIFI, 31 CH absorption features with different radial velocities and line widths are detected and identified. The narrower line width and lower column density clouds show "spiral arm" cloud characteristics, while the absorption component with the broadest line width and highest column density corresponds to the gas from the Sgr B2 envelope. The observations show that each "spiral arm" harbors multiple velocity components, indicating that the clouds are not uniform and that they have internal structure. This line-of-sight through almost the entire Galaxy offers unique possibilities to study the basic chemistry of simple molecules in diffuse clouds, as a variety of different cloud classes are sampled simultaneously. We find that the linear relationship between CH and H-2 column densities found at lower AV by UV observations does not continue into the range of higher visual extinction. There, the curve flattens, which probably means that CH is depleted in the denser cores of these clouds.
g10.6-0.4
spectroscopy
sagittarius b2
cologne database
chemistry
microwave
submillimeter
molecular clouds
ISM: molecules
hydrogen
sight-line
ISM: abundances
Author
S. L. Qin
University of Cologne
P. Schilke
Max Planck Society
University of Cologne
C. Comito
Max Planck Society
T. Moller
University of Cologne
R. Rolffs
Max Planck Society
Holger Muller
University of Cologne
A. Belloche
Max Planck Society
K. M. Menten
Max Planck Society
D. C. Lis
California Institute of Technology (Caltech)
T. G. Phillips
California Institute of Technology (Caltech)
E. A. Bergin
University of Michigan
T. A. Bell
California Institute of Technology (Caltech)
N. R. Crockett
University of Michigan
G. A. Blake
California Institute of Technology (Caltech)
S. Cabrit
LUTH - Laboratoire de l'Univers et de ses Theories
E. Caux
LUTH - Laboratoire de l'Univers et de ses Theories
University of Toulouse
C. Ceccarelli
Laboratoire d'Astrophysique de l'Observatoire de Grenoble
J. Cernicharo
Centro de Astrobiologia (CAB)
F. Daniel
LUTH - Laboratoire de l'Univers et de ses Theories
Centro de Astrobiologia (CAB)
M. L. Dubernet
LUTH - Laboratoire de l'Univers et de ses Theories
M. Emprechtinger
California Institute of Technology (Caltech)
P. Encrenaz
LUTH - Laboratoire de l'Univers et de ses Theories
E. Falgarone
LUTH - Laboratoire de l'Univers et de ses Theories
M. Gerin
LUTH - Laboratoire de l'Univers et de ses Theories
T. F. Giesen
University of Cologne
J. R. Goicoechea
Centro de Astrobiologia (CAB)
P. F. Goldsmith
California Institute of Technology (Caltech)
H. Gupta
California Institute of Technology (Caltech)
E. Herbst
Ohio State University
C. Joblin
LUTH - Laboratoire de l'Univers et de ses Theories
D. Johnstone
National Research Council Canada
W. D. Langer
California Institute of Technology (Caltech)
S. D. Lord
California Institute of Technology (Caltech)
S. Maret
Laboratoire d'Astrophysique de l'Observatoire de Grenoble
P. G. Martin
Canadian Institute for Theoretical Astrophysics
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
P. Morris
California Institute of Technology (Caltech)
J. A. Murphy
Maynooth University
D. A. Neufeld
Johns Hopkins University
V. Ossenkopf
University of Cologne
Netherlands Institute for Space Research (SRON)
L. Pagani
LUTH - Laboratoire de l'Univers et de ses Theories
J. C. Pearson
California Institute of Technology (Caltech)
M. Perault
LUTH - Laboratoire de l'Univers et de ses Theories
R. Plume
University of Calgary
M. Salez
LUTH - Laboratoire de l'Univers et de ses Theories
S. Schlemmer
University of Cologne
J. Stutzki
University of Cologne
N. Trappe
Maynooth University
F. F. S. van der Tak
Netherlands Institute for Space Research (SRON)
C. Vastel
LUTH - Laboratoire de l'Univers et de ses Theories
University of Toulouse
S. Wang
University of Michigan
H. W. Yorke
California Institute of Technology (Caltech)
S. Yu
California Institute of Technology (Caltech)
J. Zmuidzinas
California Institute of Technology (Caltech)
A. Boogert
California Institute of Technology (Caltech)
R. Güsten
Max Planck Society
P. Hartogh
MPI für Sonnensystemforschung
N. Honingh
University of Cologne
A. Karpov
California Institute of Technology (Caltech)
J. Kooi
California Institute of Technology (Caltech)
J. M. Krieg
LUTH - Laboratoire de l'Univers et de ses Theories
R. Schieder
University of Cologne
M. C. Diez-Gonzalez
Yebes Observatory
R. Bachiller
Yebes Observatory
J. Martin-Pintado
Centro de Astrobiologia (CAB)
W. Baechtold
Swiss Federal Institute of Technology in Zürich (ETH)
Michael Olberg
Chalmers, Earth and Space Sciences, Onsala Space Observatory
L. H. Nordh
Stockholm University
J. L. Gill
California Institute of Technology (Caltech)
Goutam Chattopadhyay
California Institute of Technology (Caltech)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 521 1 Art. no. L14 - L14Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201015107