Ortho-to-para ratio of interstellar heavy water
Journal article, 2010

Context. Despite the low elemental deuterium abundance in the Galaxy, enhanced molecular D/H ratios have been found in the environments of low-mass star-forming regions, and in particular the Class 0 protostar IRAS 16293-2422. Aims. The CHESS (Chemical HErschel Surveys of Star forming regions) key program aims to study the molecular complexity of the interstellar medium. The high sensitivity and spectral resolution of the Herschel/HIFI instrument provide a unique opportunity to observe the fundamental 1(1,1)-0(0,0) transition of the ortho-D2O molecule, which is inaccessible from the ground, and determine the ortho-to-para D2O ratio. Methods. We detected the fundamental transition of the ortho-D2O molecule at 607.35 GHz towards IRAS 16293-2422. The line is seen in absorption with a line opacity of 0.62 +/- 0.11 (1 sigma). From the previous ground-based observations of the fundamental 1(1,0)-1(0,1) transition of para-D2O seen in absorption at 316.80 GHz, we estimate a line opacity of 0.26 +/- 0.05 (1 sigma). Results. We show that the observed absorption is caused by the cold gas in the envelope of the protostar. Using these new observations, we estimate for the first time the ortho-to-para D2O ratio to be lower than 2.6 at a 3 sigma level of uncertainty, which should be compared with the thermal equilibrium value of 2:1.

submillimeter: ISM

spectroscopy

ISM: abundances

protostar iras 16293-2422

envelope

constraints

astrochemistry

ISM: molecules

molecular processes

line: identification

Author

C. Vastel

Universite Paul Sabatier Toulouse III

Institut National des Sciences de l'Univers

C. Ceccarelli

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

Université Grenoble Alpes

E. Caux

Universite Paul Sabatier Toulouse III

Institut National des Sciences de l'Univers

A. Coutens

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

J. Cernicharo

Centro de Astrobiologia (CAB)

S. Bottinelli

Universite Paul Sabatier Toulouse III

Institut National des Sciences de l'Univers

K. Demyk

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

A. Faure

Université Grenoble Alpes

L. Wiesenfeld

Université Grenoble Alpes

Y. Scribano

U.M.R. 5209 C.N.R.S.

A. Bacmann

Université Grenoble Alpes

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

P. Hily-Blant

Université Grenoble Alpes

S. Maret

Université Grenoble Alpes

A. Walters

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

E. A. Bergin

University of Michigan

G. A. Blake

California Institute of Technology (Caltech)

A. Castets

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

Université Grenoble Alpes

N. Crimier

Université Grenoble Alpes

Centro de Astrobiologia (CAB)

C. Dominik

Anton Pannekoek Institute for Astronomy

Radboud University

P. Encrenaz

Ecole Normale Superieure (ENS)

M. Gerin

Ecole Normale Superieure (ENS)

P. Hennebelle

Ecole Normale Superieure (ENS)

C. Kahane

Université Grenoble Alpes

A. Klotz

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

G. J. Melnick

Harvard-Smithsonian Center for Astrophysics

L. Pagani

Ecole Normale Superieure (ENS)

B. Parise

Max Planck Institute

P. Schilke

University of Cologne

Max Planck Institute

V. Wakelam

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

A. Baudry

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

T. A. Bell

California Institute of Technology (Caltech)

M. Benedettini

Istituto di Fisica dello Spazio Interplanetario, Rome

A. Boogert

California Institute of Technology (Caltech)

S. Cabrit

Ecole Normale Superieure (ENS)

P. Caselli

University of Leeds

C. Codella

Arcetri Astrophysical Observatory

C. Comito

Max Planck Institute

E. Falgarone

Ecole Normale Superieure (ENS)

A. Fuente

Spanish National Observatory (OAN)

P. F. Goldsmith

Jet Propulsion Laboratory, California Institute of Technology

F. Helmich

Netherlands Institute for Space Research (SRON)

T. Henning

Max Planck Institute

E. Herbst

Ohio State University

T. Jacq

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

M. Kama

Anton Pannekoek Institute for Astronomy

W. D. Langer

Jet Propulsion Laboratory, California Institute of Technology

B. Lefloch

Université Grenoble Alpes

D. Lis

California Institute of Technology (Caltech)

S. Lord

California Institute of Technology (Caltech)

A. Lorenzani

Arcetri Astrophysical Observatory

D. A. Neufeld

Johns Hopkins University

B. Nisini

Osservatorio Astronomico di Roma

S. Pacheco

Université Grenoble Alpes

J. C. Pearson

Jet Propulsion Laboratory, California Institute of Technology

T. Phillips

California Institute of Technology (Caltech)

M. Salez

Ecole Normale Superieure (ENS)

P. Saraceno

Istituto di Fisica dello Spazio Interplanetario, Rome

K. Schuster

Institut de RadioAstronomie Millimetrique (IRAM)

X. Tielens

Leiden University

F. F. S. van der Tak

University of Groningen

Netherlands Institute for Space Research (SRON)

M. H. D. van der Wiel

Netherlands Institute for Space Research (SRON)

University of Groningen

S. Viti

University College London (UCL)

F. Wyrowski

Max Planck Institute

H. W. Yorke

Jet Propulsion Laboratory, California Institute of Technology

P. Cais

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

J. M. Krieg

Ecole Normale Superieure (ENS)

Michael Olberg

Chalmers, Earth and Space Sciences, Onsala Space Observatory

L. Ravera

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

Astronomy and Astrophysics

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

Vol. 521 1 Article Number: L31 - L31

Subject Categories

Astronomy, Astrophysics and Cosmology

Roots

Basic sciences

DOI

10.1051/0004-6361/201015101

More information

Latest update

9/6/2018 1