Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data
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Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data. / Coutens, Audrey; Vastel, C.; Hincelin, U.; Herbst, E.; Lis, D. C.; Chavarría, L.; Gérin, M.; van der Tak, F. F. S.; Persson, C. M.; Goldsmith, P. F.; Caux, E.
In: Monthly Notices of the Royal Astronomical Society, Vol. 445, No. 2, 2014, p. 1299-1313.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data
AU - Coutens, Audrey
AU - Vastel, C.
AU - Hincelin, U.
AU - Herbst, E.
AU - Lis, D. C.
AU - Chavarría, L.
AU - Gérin, M.
AU - van der Tak, F. F. S.
AU - Persson, C. M.
AU - Goldsmith, P. F.
AU - Caux, E.
PY - 2014
Y1 - 2014
N2 - Understanding water deuterium fractionation is important for constraining the mechanisms of water formation in interstellar clouds. Observations of HDO and H_2^{18}O 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 H_2^{18}O 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.
AB - Understanding water deuterium fractionation is important for constraining the mechanisms of water formation in interstellar clouds. Observations of HDO and H_2^{18}O 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 H_2^{18}O 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.
KW - astrochemistry/ ISM: abundances/ ISM: individual objects: G34.26+0.15/ ISM: molecules
U2 - 10.1093/mnras/stu1816
DO - 10.1093/mnras/stu1816
M3 - Journal article
VL - 445
SP - 1299
EP - 1313
JO - Royal Astronomical Society. Monthly Notices
JF - Royal Astronomical Society. Monthly Notices
SN - 0035-8711
IS - 2
ER -
ID: 125455213