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Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2010

The distribution of water in the high-mass star-forming region NGC 6334 I

H. Aarts
  • Fonction : Auteur
Alain Baudry
  • Fonction : Auteur
  • PersonId : 853057
ESO
P. Caselli
J. Cernicharo
A. Coutens
C. Dominik
A. Fuente
P. Hennebelle
T. Henning
T. Jacq
  • Fonction : Auteur
J. Kooi
  • Fonction : Auteur
B. Lefloch
A. Loose
  • Fonction : Auteur
S. Maret
B. Nisini
Justin Pearson
  • Fonction : Auteur
  • PersonId : 829524
C. Risacher
ESO
Valentine Wakelam
  • Fonction : Auteur
  • PersonId : 828581

Résumé

Aims: We present observations of twelve rotational transitions of H_216O, H_218O, and H_217O toward the massive star-forming region NGC 6334 I, carried out with Herschel/HIFI as part of the guaranteed time key program Chemical HErschel Surveys of Star forming regions (CHESS). We analyze these observations to obtain insights into physical processes in this region. Methods: We identify three main gas components (hot core, cold foreground, and outflow) in NGC 6334 I and derive the physical conditions in these components. Results: The hot core, identified by the emission in highly excited lines, shows a high excitation temperature of ~200 K, whereas water in the foreground component is predominantly in the ortho- and para- ground states. The abundance of water varies between 4 × 10-5 (outflow) and 10-8 (cold foreground gas). This variation is most likely due to the freeze-out of water molecules onto dust grains. The H_218O/H_217O abundance ratio is 3.2, which is consistent with the 18O/17O ratio determined from CO isotopologues. The ortho/para ratio in water appears to be relatively low (1.6±1) in the cold, quiescent gas, but close to the equilibrium value of three in the warmer outflow material (2.5±0.8). Herschel is an ESA space observatory with science instruments provided by European-led principal Investigator consortia and with important participation from NASA.Figures 1, 2 and 3 and Tables 2-4 (pages 5 to 6) are only available in electronic form at http://www.aanda.org

Dates et versions

hal-00633423 , version 1 (18-10-2011)

Identifiants

Citer

M. Emprechtinger, D. C. Lis, T. Bell, T. G. Phillips, P. Schilke, et al.. The distribution of water in the high-mass star-forming region NGC 6334 I. Astronomy and Astrophysics - A&A, 2010, 521, pp.L28. ⟨10.1051/0004-6361/201015086⟩. ⟨hal-00633423⟩
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