Herschel/HIFI measurements of the ortho/para ratio in water towards Sagittarius B2(M) and W31C
Journal article, 2010
We present Herschel/HIFI observations of the fundamental rotational transitions of ortho- and para-H216O and H218O in absorption towards Sagittarius B2(M) and W31C. The ortho/para ratio in water in the foreground clouds on the line of sight towards these bright continuum sources is generally consistent with the statistical high-temperature ratio of 3, within the observational uncertainties. However, somewhat unexpectedly, we derive a low ortho/para ratio of 2.35 +/- 0.35, corresponding to a spin temperature of similar to 27 K, towards Sagittarius B2(M) at velocities of the expanding molecular ring. Water molecules in this region appear to have formed with, or relaxed to, an ortho/para ratio close to the value corresponding to the local temperature of the gas and dust.
ISM: abundances
ammonia
molecular clouds
absorption
submillimeter: ISM
astrochemistry
ISM: molecules
astronomy
cdms
molecular processes
spectroscopy
cologne database
submillimeter
vapor
oxygen
Author
D. C. Lis
California Institute of Technology (Caltech)
T. G. Phillips
California Institute of Technology (Caltech)
P. F. Goldsmith
California Institute of Technology (Caltech)
D. A. Neufeld
Johns Hopkins University
E. Herbst
Ohio State University
C. Comito
Max Planck Society
P. Schilke
University of Cologne
Max Planck Society
Holger Muller
University of Cologne
E. A. Bergin
University of Michigan
M. Gerin
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
T. A. Bell
California Institute of Technology (Caltech)
M. Emprechtinger
California Institute of Technology (Caltech)
John H Black
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
G. A. Blake
California Institute of Technology (Caltech)
F. Boulanger
Institut d'Astrophysique Spatiale
E. Caux
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
University of Toulouse
C. Ceccarelli
Laboratoire d'Astrophysique de l'Observatoire de Grenoble
J. Cernicharo
Centro de Astrobiologia (CAB)
A. Coutens
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
University of Toulouse
N. R. Crockett
University of Michigan
F. Daniel
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
Centro de Astrobiologia (CAB)
E. Dartois
Institut d'Astrophysique Spatiale
M. de Luca
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
M. L. Dubernet
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
P. Encrenaz
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
E. Falgarone
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
T. R. Geballe
Gemini Observatory North
B. Godard
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
T. F. Giesen
University of Cologne
J. R. Goicoechea
Centro de Astrobiologia (CAB)
C. Gry
California Institute of Technology (Caltech)
H. Gupta
California Institute of Technology (Caltech)
P. Hennebelle
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
P. Hily-Blant
Laboratoire d'Astrophysique de l'Observatoire de Grenoble
R. Kolos
Polish Academy of Sciences
J. Krelowski
Nicolaus Copernicus University
C. Joblin
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
University of Toulouse
D. Johnstone
National Research Council Canada
M. Kazmierczak
Nicolaus Copernicus University
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
J. Martin-Pintado
Centro de Astrobiologia (CAB)
G. J. Melnick
Harvard-Smithsonian Center for Astrophysics
K. M. Menten
Max Planck Society
Raquel Monje
California Institute of Technology (Caltech)
B. Mookerjea
Tata Institute of Fundamental Research
P. Morris
California Institute of Technology (Caltech)
J. A. Murphy
Maynooth University
V. Ossenkopf
University of Cologne
Netherlands Institute for Space Research (SRON)
J. C. Pearson
California Institute of Technology (Caltech)
M. Perault
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
Carina Persson
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
R. Plume
University of Calgary
S. L. Qin
University of Cologne
M. Salez
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
S. Schlemmer
University of Cologne
M. Schmidt
Polish Academy of Sciences
P. Sonnentrucker
Johns Hopkins University
J. Stutzki
University of Cologne
D. Teyssier
European Space Agency (ESA)
N. Trappe
Maynooth University
F. F. S. van der Tak
Netherlands Institute for Space Research (SRON)
C. Vastel
University of Toulouse
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
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)
N. Erickson
University of Massachusetts
A. Karpov
California Institute of Technology (Caltech)
J. Kooi
California Institute of Technology (Caltech)
F. W. Maiwald
California Institute of Technology (Caltech)
R. Schieder
University of Cologne
P. Zaal
Netherlands Institute for Space Research (SRON)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 521 1 Article Number: L26 - L26Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201015072