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

Chavarria, L., Herpin, F., Jacq, T., Braine, J., Bontemps, S., Baudry, A., Marseille, M., van der Tak, F., Pietropaoli, B., Wyrowski, F., Shipman, R., Frieswijk, W., van Dishoeck, E. F., Cernicharo, J., Bachiller, R., Benedettini, M., Benz, A. O., Bergin, E., Bjerkeli, P., Blake, G. A., Bruderer, S., Caselli, P., Codella, C., Daniel, F., di Giorgio, A. M., Dominik, C., Doty, S. D., Encrenaz, P., Fich, M., Fuente, A., Giannini, T., Goicoechea, J. R., de Graauw, Th., Hartogh, P., Helmich, F., Herczeg, G. J., Hogerheijde, M. R., Johnstone, D., Jorgensen, J. K., Kristensen, L. E., Larsson, B., Lis, D., Liseau, R., McCoey, C., Melnick, G., Nisini, B., Olberg, M., Parise, Berengere, Pearson, J. C., Plume, R., Risacher, C., Santiago-Garcia, J., Saraceno, P., Stutzki, J., Szczerba, R., Tafalla, M., Tielens, A., van Kempen, T. A., Visser, R., Wampfler, S. F., Willem, J. and Yildiz, U. A. 2010. Water in massive star-forming regions: HIFI observations of W3 IRS5. Astronomy and Astrophysics 521 , L37. 10.1051/0004-6361/201015113

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Abstract

We present Herschel observations of the water molecule in the massive star-forming region W3 IRS5. The o-H217O 110-101, p-H218O 111-000, p-H2O 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-H217O 110-101 and p-H218O 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.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Uncontrolled Keywords:	stars: formation ; stars: massive ; ISM: molecules ; ISM: abundances ; dust, extinction ; radio lines: ISM
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0004-6361/ (accessed 16/04/2014)
Publisher:	EDP Sciences
ISSN:	0004-6361
Date of First Compliant Deposit:	30 March 2016
Last Modified:	27 May 2023 00:56
URI:	https://orca.cardiff.ac.uk/id/eprint/52785

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