Hydrides in young stellar objects: radiation tracers in a protostar-disk-outflow system [Letter]

Benz, A. O., Bruderer, S., van Dishoeck, E. F., Staeuber, P., Wampfler, S. F., Melchior, M., Dedes, C., Wyrowski, F., Doty, S. D., van der Tak, F., Baechtold, W., Csillaghy, A., Megej, A., Monstein, C., Soldati, M., Bachiller, R., Baudry, A., Benedettini, M., Bergin, E., Bjerkeli, P., Blake, G. A., Bontemps, S., Braine, J., Caselli, P., Cernicharo, J., Codella, C., Daniel, F., di Giorgio, A. M., Dieleman, P., Dominik, C., Encrenaz, P., Fich, M., Fuente, A., Giannini, T., Goicoechea, J. R., de Graauw, Th., Helmich, F., Herczeg, G. J., Herpin, F., Hogerheijde, M. R., Jacq, T., Jellema, W., Johnstone, D., Jorgensen, J. K., Kristensen, L. E., Larsson, B., Lis, D., Liseau, R., Marseille, M., McCoey, C., Melnick, G., Neufeld, D., Nisini, B., Olberg, M., Ossenkopf, V., Parise, Berengere, Pearson, J. C., Plume, R., Risacher, C., Santiago-Garcia, J., Saraceno, P., Schieder, R., Shipman, R., Stutzki, J., Tafalla, M., Tielens, A. G. G. M., van Kempen, T. A., Visser, R. and Yildiz, U. A. 2010. Hydrides in young stellar objects: radiation tracers in a protostar-disk-outflow system [Letter]. Astronomy and Astrophysics 521 , L35. 10.1051/0004-6361/201015111

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Abstract

Context. Hydrides of the most abundant heavier elements are fundamental molecules in cosmic chemistry. Some of them trace gas irradiated by UV or X-rays. Aims. We explore the abundances of major hydrides in W3 IRS5, a prototypical region of high-mass star formation. Methods. W3 IRS5 was observed by HIFI on the Herschel Space Observatory with deep integration (2500 s) in 8 spectral regions. Results. The target lines including CH, NH, H3O+, and the new molecules SH+, H2O+, and OH+ are detected. The H2O+ and OH+ J = 1–0 lines are found mostly in absorption, but also appear to exhibit weak emission (P-Cyg-like). Emission requires high density, thus originates most likely near the protostar. This is corroborated by the absence of line shifts relative to the young stellar object (YSO). In addition, H2O+ and OH+ also contain strong absorption components at a velocity shifted relative to W3 IRS5, which are attributed to foreground clouds. Conclusions. The molecular column densities derived from observations correlate well with the predictions of a model that assumes the main emission region is in outflow walls, heated and irradiated by protostellar UV radiation.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Uncontrolled Keywords:	astrochemistry ; line: identification ; stars: formation / stars: massive ; photon-dominated region ; submillimeter: ISM
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0004-6361/ (accessed 17/04/2014)
Publisher:	EDP Sciences
ISSN:	0004-6361
Date of First Compliant Deposit:	30 March 2016
Last Modified:	06 May 2023 23:40
URI:	https://orca.cardiff.ac.uk/id/eprint/52799

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