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arXiv · 1007.3370

Hydrides in Young Stellar Objects: Radiation tracers in a protostar-disk-outflow system

Arnold O. Benz·Simon Bruderer·Ewine F. van Dishoeck·WISH Team·HIFI Team
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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 (about 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.

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Arnold O. Benz, Simon Bruderer, Ewine F. van Dishoeck, WISH Team, HIFI Team. 2010-07-20. Hydrides in Young Stellar Objects: Radiation tracers in a protostar-disk-outflow system. https://doi.org/10.1051/0004-6361/201015111

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