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.

spectroscopy

submillimeter

absorption

oxygen

molecular clouds

molecular processes

ISM: abundances

submillimeter: ISM

vapor

ISM: molecules

astrochemistry

cologne database

astronomy

ammonia

cdms

Author

D. C. Lis

California Institute of Technology (Caltech)

T. G. Phillips

California Institute of Technology (Caltech)

P. F. Goldsmith

Jet Propulsion Laboratory, California Institute of Technology

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

University of Toulouse

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

N. R. Crockett

University of Michigan

F. Daniel

Centro de Astrobiologia (CAB)

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

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

Jet Propulsion Laboratory, California Institute of Technology

H. Gupta

Jet Propulsion Laboratory, California Institute of Technology

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

Uniwersytet Mikołaja Kopernika w Toruniu

C. Joblin

University of Toulouse

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

D. Johnstone

National Research Council Canada

M. Kazmierczak

Uniwersytet Mikołaja Kopernika w Toruniu

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

Netherlands Institute for Space Research (SRON)

University of Cologne

J. C. Pearson

Jet Propulsion Laboratory, California Institute of Technology

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 Astronomy Centre (ESAC)

N. Trappe

Maynooth University

F. F. S. van der Tak

Netherlands Institute for Space Research (SRON)

C. Vastel

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

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)

N. Erickson

University of Massachusetts

A. Karpov

California Institute of Technology (Caltech)

J. Kooi

California Institute of Technology (Caltech)

F. W. Maiwald

Jet Propulsion Laboratory, California Institute of Technology

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 - L26

Subject Categories

Astronomy, Astrophysics and Cosmology

DOI

10.1051/0004-6361/201015072

More information

Latest update

1/28/2020