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.

submillimeter

cologne database

ISM: molecules

g10.6-0.4

hydrogen

sagittarius b2

spectroscopy

ISM: abundances

chemistry

sight-line

microwave

molecular clouds

Author

S. L. Qin

University of Cologne

P. Schilke

Max Planck Institute

University of Cologne

C. Comito

Max Planck Institute

T. Moller

University of Cologne

R. Rolffs

Max Planck Institute

Holger Muller

University of Cologne

A. Belloche

Max Planck Institute

K. M. Menten

Max Planck Institute

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

Centro de Astrobiologia (CAB)

LUTH - Laboratoire de l'Univers et de ses Theories

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

Jet Propulsion Laboratory, California Institute of Technology

H. Gupta

Jet Propulsion Laboratory, California Institute of Technology

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

Jet Propulsion Laboratory, California Institute of Technology

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

Jet Propulsion Laboratory, California Institute of Technology

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

Jet Propulsion Laboratory, California Institute of Technology

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

Jet Propulsion Laboratory, California Institute of Technology

S. Yu

Jet Propulsion Laboratory, California Institute of Technology

J. Zmuidzinas

California Institute of Technology (Caltech)

A. Boogert

California Institute of Technology (Caltech)

R. Güsten

Max Planck Institute

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

Centro Astronomico de Yebes

R. Bachiller

Centro Astronomico de Yebes

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

Jet Propulsion Laboratory, California Institute of Technology

Goutam Chattopadhyay

Jet Propulsion Laboratory, California Institute of Technology

Astronomy and Astrophysics

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

Vol. 521 1 Art. no. L14 - L14

Subject Categories

Astronomy, Astrophysics and Cosmology

DOI

10.1051/0004-6361/201015107

More information

Latest update

9/6/2018 1