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.

envelope

molecular processes

submillimeter: ISM

ISM: abundances

ISM: molecules

line: identification

protostar iras 16293-2422

spectroscopy

astrochemistry

constraints

Författare

C. Vastel

Universite Paul Sabatier Toulouse III

Institut National des Sciences de l'Univers

C. Ceccarelli

Laboratoire d'Astrophysique de Bordeaux

Universite Grenoble Alpes

Institut National des Sciences de l'Univers

E. Caux

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

A. Coutens

Universite Paul Sabatier Toulouse III

Institut National des Sciences de l'Univers

J. Cernicharo

CSIC-INTA - Centro de Astrobiologia (CAB)

S. Bottinelli

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

K. Demyk

Universite Paul Sabatier Toulouse III

Institut National des Sciences de l'Univers

A. Faure

Universite Grenoble Alpes

L. Wiesenfeld

Universite Grenoble Alpes

Y. Scribano

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

A. Bacmann

Universite Grenoble Alpes

Institut National des Sciences de l'Univers

Laboratoire d'Astrophysique de Bordeaux

P. Hily-Blant

Universite Grenoble Alpes

S. Maret

Universite Grenoble Alpes

A. Walters

Institut National des Sciences de l'Univers

Universite Paul Sabatier Toulouse III

E. A. Bergin

University Michigan Ann Arbor

G. A. Blake

California Institute of Technology

A. Castets

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

Universite Grenoble Alpes

N. Crimier

Universite Grenoble Alpes

CSIC-INTA - Centro de Astrobiologia (CAB)

C. Dominik

Radboud University Nijmegen

Astronomical Institute Anton Pannekoek

P. Encrenaz

École Normale Supérieure

M. Gerin

École Normale Supérieure

P. Hennebelle

École Normale Supérieure

C. Kahane

Universite 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

École Normale Supérieure

B. Parise

Max Planck-institutet

P. Schilke

Universitat zu Koln

Max Planck-institutet

V. Wakelam

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

A. Baudry

Laboratoire d'Astrophysique de Bordeaux

Institut National des Sciences de l'Univers

T. A. Bell

California Institute of Technology

M. Benedettini

Istituto di Fisica dello Spazio Interplanetario, Rome

A. Boogert

California Institute of Technology

S. Cabrit

École Normale Supérieure

P. Caselli

University of Leeds

C. Codella

Osservatorio Astrofisico Di Arcetri

C. Comito

Max Planck-institutet

E. Falgarone

École Normale Supérieure

A. Fuente

Observatorio Astronomico Nacional

P. F. Goldsmith

Jet Propulsion Laboratory, California Institute of Technology

F. Helmich

SRON Netherlands Institute for Space Research

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

Astronomical Institute Anton Pannekoek

W. D. Langer

Jet Propulsion Laboratory, California Institute of Technology

B. Lefloch

Universite Grenoble Alpes

D. Lis

California Institute of Technology

S. Lord

California Institute of Technology

A. Lorenzani

Osservatorio Astrofisico Di Arcetri

D. A. Neufeld

Johns Hopkins University

B. Nisini

Osservatorio Astronomico di Roma

S. Pacheco

Universite Grenoble Alpes

J. C. Pearson

Jet Propulsion Laboratory, California Institute of Technology

T. Phillips

California Institute of Technology

M. Salez

École Normale Supérieure

P. Saraceno

Istituto di Fisica dello Spazio Interplanetario, Rome

K. Schuster

IRAM Institut de RadioAstronomie Millimetrique

X. Tielens

Leiden Observatory Research Institute

F. F. S. van der Tak

SRON Netherlands Institute for Space Research

University of Groningen, Kapteyn Astronomical Institute

M. H. D. van der Wiel

SRON Netherlands Institute for Space Research

University of Groningen, Kapteyn Astronomical Institute

S. Viti

UCL

F. Wyrowski

Max Planck-institutet

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

École Normale Supérieure

Michael Olberg

Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium

L. Ravera

Universite Paul Sabatier Toulouse III

Institut National des Sciences de l'Univers

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