Ortho-to-para ratio of interstellar heavy water
Artikel i vetenskaplig tidskrift, 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.

constraints

protostar iras 16293-2422

ISM: molecules

submillimeter: ISM

molecular processes

envelope

line: identification

spectroscopy

astrochemistry

ISM: abundances

Författare

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

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

A. Coutens

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

J. Cernicharo

Centro de Astrobiologia (CAB)

S. Bottinelli

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

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

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

Université Grenoble Alpes

P. Hily-Blant

Université Grenoble Alpes

S. Maret

Université Grenoble Alpes

A. Walters

Universite Paul Sabatier Toulouse III

Institut National des Sciences de l'Univers

E. A. Bergin

University of Michigan

G. A. Blake

CalTech

A. Castets

Université Grenoble Alpes

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

N. Crimier

Centro de Astrobiologia (CAB)

Université Grenoble Alpes

C. Dominik

Radboud Universiteit

Anton Pannekoek Institute for Astronomy

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

Universite Paul Sabatier Toulouse III

Institut National des Sciences de l'Univers

G. J. Melnick

Harvard-Smithsonian Center for Astrophysics

L. Pagani

Ecole Normale Superieure (ENS)

B. Parise

Max Planck-institutet

P. Schilke

Universität zu Köln

Max Planck-institutet

V. Wakelam

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

A. Baudry

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

T. A. Bell

CalTech

M. Benedettini

Istituto di Fisica dello Spazio Interplanetario, Rome

A. Boogert

CalTech

S. Cabrit

Ecole Normale Superieure (ENS)

P. Caselli

University of Leeds

C. Codella

Osservatorio Astrofisico di Arcetri

C. Comito

Max Planck-institutet

E. Falgarone

Ecole Normale Superieure (ENS)

A. Fuente

Observatorio Astronomico Nacional

P. F. Goldsmith

Jet Propulsion Laboratory, California Institute of Technology

F. Helmich

Netherlands Institute for Space Research (SRON)

T. Henning

Max Planck-institutet

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

CalTech

S. Lord

CalTech

A. Lorenzani

Osservatorio Astrofisico di Arcetri

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

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

Universiteit Leiden

F. F. S. van der Tak

Netherlands Institute for Space Research (SRON)

Rijksuniversiteit Groningen

M. H. D. van der Wiel

Netherlands Institute for Space Research (SRON)

Rijksuniversiteit Groningen

S. Viti

University College London (UCL)

F. Wyrowski

Max Planck-institutet

H. W. Yorke

Jet Propulsion Laboratory, California Institute of Technology

P. Cais

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

J. M. Krieg

Ecole Normale Superieure (ENS)

Michael Olberg

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

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 Article Number: L31 - L31

Ämneskategorier

Astronomi, astrofysik och kosmologi

Fundament

Grundläggande vetenskaper

DOI

10.1051/0004-6361/201015101