Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data
Artikel i vetenskaplig tidskrift, 2014

Understanding water deuterium fractionation is important for constraining the mechanisms of water formation in interstellar clouds. Observations of HDO and H182O transitions were carried out towards the high-mass star-forming region G34.26+0.15 with the Heterodyne Instrument for the Far-Infrared (HIFI) instrument onboard the Herschel Space Observatory, as well as with ground-based single-dish telescopes. 10 HDO lines and three H182O lines covering a broad range of upper energy levels (22–204 K) were detected. We used a non-local thermal equilibrium 1D analysis to determine the HDO/H2O ratio as a function of radius in the envelope. Models with different water abundance distributions were considered in order to reproduce the observed line profiles. The HDO/H2O ratio is found to be lower in the hot core (∼3.5 × 10−4–7.5 × 10−4) than in the colder envelope (∼1.0 × 10−3–2.2 × 10−3). This is the first time that a radial variation of the HDO/H2O ratio has been found to occur in a high-mass source. The chemical evolution of this source was modelled as a function of its radius and the observations are relatively well reproduced. The comparison between the chemical model and the observations leads to an age of ∼105 yr after the infrared dark cloud stage.

astrochemistry ISM: abundances ISM: individual objects: G34.26+0.15 ISM: molecules

Författare

A. Coutens

Kobenhavns Universitet

Niels Bohr Institute

C. Vastel

Universite de Toulouse

CNRS Centre National de la Recherche Scientifique

U Hincelin

University of Virginia

E. Herbst

University of Virginia

D. Lis

Universite Pierre et Marie Curie

CalTech

L. Chavarría

Universidad de Chile

M. Gerin

École Normale Supérieure

F. F. S. van der Tak

University of Groningen, Kapteyn Astronomical Institute

SRON Netherlands Institute for Space Research

Carina Persson

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

P.E. Goldsmith

Jet Propulsion Laboratory, California Institute of Technology

E. Caux

CNRS Centre National de la Recherche Scientifique

Universite de Toulouse

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 445 1299-1313

Ämneskategorier

Astronomi, astrofysik och kosmologi

Fundament

Grundläggande vetenskaper

Infrastruktur

Onsala rymdobservatorium

DOI

10.1093/mnras/stu1816