Water in massive star-forming regions: HIFI observations of W3 IRS5

L. Chavarria (1, 2, 3, 4) , Fabrice Herpin (1, 2, 3, 4) , T. Jacq (1, 2, 3, 4) , J. Braine (1, 2, 3, 4) , Sylvain Bontemps (1, 2, 3, 4) , Alain Baudry (1, 2, 3, 4) , M. Marseille (1, 2, 3, 4, 5) , F. van Der Tak (6) , B. Pietropaoli , F. Wyrowski (7) , R. Shipman , W. Frieswijk , E. F. van Dishoeck , J. Cernicharo (8) , R. Bachiller (6) , M. Benedettini (6) , A. O. Benz , E. Bergin , P. Bjerkeli , G. A. Blake (9) , S. Bruderer , P. Caselli (10) , C. Codella (6) , F. Daniel , A. M. Di Giorgio , C. Dominik (11) , S. D. Doty , P. Encrenaz (12) , M. Fich , A. Fuente (6) , T. Giannini , J. R. Goicoechea (12) , Th. de Graauw , P. Hartogh (13) , F. Helmich (6) , G. J. Herczeg , M. R. Hogerheijde , D. Johnstone , J. K. Jørgensen , L. E. Kristensen , B. Larsson (6) , D. Lis (6) , R. Liseau , C. Mccoey , G. Melnick (6) , B. Nisini (14) , M. Olberg (15) , B. Parise (16) , J. C. Pearson , R. Plume , C. Risacher (17) , J. Santiago-Garcia , P. Saraceno (18) , J. Stutzki R. Szczerba , M. Tafalla , A. Tielens , T. A. van Kempen , R. Visser , S. F. Wampfler , J. Willem , U. A. Yildiz

1 LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac]
2 OASU - Observatoire aquitain des sciences de l'univers
3 UB - Université Sciences et Technologies - Bordeaux 1
4 L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux
5 SRON - SRON Netherlands Institute for Space Research
6 LAOG - Laboratoire d'Astrophysique de Grenoble
7 MPIFR - Max-Planck-Institut für Radioastronomie
8 CSIC - Centro de Investigaciones Biológicas
9 LOCIE - LabOratoire proCédés énergIe bâtimEnt
10 OAA - INAF - Osservatorio Astrofisico di Arcetri
11 AI PANNEKOEK - Astronomical Institute Anton Pannekoek
12 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
13 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
14 OAR - INAF - Osservatorio Astronomico di Roma
15 Onsala Space Observatory
16 CESR - Centre d'étude spatiale des rayonnements
17 ESO
18 IFSI - Istituto di Fisica dello Spazio Interplanetario

We present Herschel observations of the water molecule in the massive star-forming region W3 IRS5. The o-H17O 110-101, p-H18O 111-000, p-H2O 22 202-111, p-H2O 111-000, o-H2O 221-212, and o-H2O 212-101 lines, covering a frequency range from 552 up to 1669 GHz, have been detected at high spectral resolution with HIFI. The water lines in W3 IRS5 show well-defined high-velocity wings that indicate a clear contribution by outflows. Moreover, the systematically blue-shifted absorption in the H2O lines suggests expansion, presumably driven by the outflow. No infall signatures are detected. The p-H2O 111-000 and o-H2O 212-101 lines show absorption from the cold material (T ~ 10 K) in which the high-mass protostellar envelope is embedded. One-dimensional radiative transfer models are used to estimate water abundances and to further study the kinematics of the region. We show that the emission in the rare isotopologues comes directly from the inner parts of the envelope (T > 100 K) where water ices in the dust mantles evaporate and the gas-phase abundance increases. The resulting jump in the water abundance (with a constant inner abundance of 10^{-4}) is needed to reproduce the o-H17O 110-101 and p-H18O 111-000 spectra in our models. We estimate water abundances of 10^{-8} to 10^{-9} in the outer parts of the envelope (T < 100 K). The possibility of two protostellar objects contributing to the emission is discussed.

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]; Astrophysique stellaire et solaire [astro-ph.SR]

L. Chavarria, Fabrice Herpin, T. Jacq, J. Braine, Sylvain Bontemps, et al.. Water in massive star-forming regions: HIFI observations of W3 IRS5. Astronomy and Astrophysics - A&A, 2010, 521, pp.L37. ⟨10.1051/0004-6361/201015113⟩. ⟨hal-00521355⟩