Sulphur chemistry in the envelopes of massive young stars

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dc.creatorvan der Tak, F. F. S.
dc.creatorBoonman, A. M. S.
dc.creatorBraakman, R.
dc.creatorvan Dishoeck, E. F.
dc.date2002-12-13
dc.date.accessioned2026-07-07T02:06:52Z
dc.date.available2026-07-07T02:06:52Z
dc.descriptionWe present submillimeter observations of SO, SO2, H2S, H2CS, OCS, NS and HCS+ toward nine massive young stars. The outflow contributes ~50% to the SO and SO2 emission in 15-20'' beams, more than for CS, where it is 10%. The SO2 abundance increases from dark cloud levels in the outer envelope (T<100 K) to levels seen in hot cores and shocks in the inner envelope (T>100 K). Molecular abundances are consistent with a model of ice evaporation in an envelope with gradients in temperature and density for a chemical age of ~30000 yr. The high observed abundance of OCS, the fact that T_ex (OCS) >> T_ex (H2S), and the data on solid OCS and H2S all suggest that the major sulphur carrier in grain mantles is OCS rather than H2S. For most other sulphur-bearing molecules, the source-to-source abundance variations by factors of up to 10 do not correlate with previously established evolutionary trends in temperature tracers. These species probe the chemically inactive outer envelope. Our data set does not constrain the abundances of H2S and SO in the inner envelope, which, together with SO2, are required to use sulphur as a clock.
dc.descriptionTo appear in: Chemistry as a diagnostic of star formation, eds. C.L. Curry & M. Fich (NRC Press). Short version (3 pages) of a paper submitted to Astronomy and Astrophysics
dc.identifierhttps://arxiv.org/abs/astro-ph/0212325
dc.identifierhttp://arxiv.org/abs/astro-ph/0212325
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/5512
dc.subjectAstrophysics
dc.titleSulphur chemistry in the envelopes of massive young stars
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