2003A&A...412..133V


Query : 2003A&A...412..133V

2003A&A...412..133V - Astronomy and Astrophysics, volume 412, 133-145 (2003/12-2)

Sulphur chemistry in the envelopes of massive young stars.

VAN DER TAK F.F.S., BOONMAN A.M.S., BRAAKMAN R. and VAN DISHOECK E.F.

Abstract (from CDS):

The sulphur chemistry in nine regions in the earliest stages of high-mass star formation is studied through single-dish submillimeter spectroscopy. The line profiles indicate that 10-50% of the SO and SO2 emission arises in high-velocity gas, either infalling or outflowing. For the low-velocity gas, excitation temperatures are 25K for H2S, 50K for SO, H2CS, NS and HCS+, and 100K for OCS and SO2, indicating that most observed emission traces the outer parts (T<100K) of the molecular envelopes, except high-excitation OCS and SO2 lines. Abundances in the outer envelopes, calculated with a Monte Carlo program, using the physical structures of the sources derived from previous submillimeter continuum and CS line data, are ∼10–8 for OCS, ∼10–9 for H2S, H2CS, SO and SO2, and ∼10–10 for HCS+ and NS. In the inner envelopes (T>100K) of six sources, the SO2 abundance is enhanced by a factor of ∼100-1000. This region of hot, abundant SO2 has been seen before in infrared absorption, and must be small, ≲0.2" (180AU radius). The derived abundance profiles are consistent with models of envelope chemistry which invoke ice evaporation at T∼100K. Shock chemistry is unlikely to contribute. A major sulphur carrier in the ices is probably OCS, not H2S as most models assume. The source-to-source abundance variations of most molecules by factors of ∼10 do not correlate with previous systematic tracers of envelope heating. Without observations of H2S and SO lines probing warm (>100K) gas, sulphur-bearing molecules cannot be used as evolutionary tracers during star formation.

Abstract Copyright:

Journal keyword(s): ISM: molecules - molecular processes - stars: circumstellar matter - stars: formation

Simbad objects: 10

goto Full paper

goto View the references in ADS

Number of rows : 10
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME W3 IRS 5 Y*O 02 25 40.54 +62 05 51.4           B1 343 0
2 NAME Mon R2 IRS 3 Y*O 06 07 47.8 -06 22 55           ~ 141 0
3 IRAS 16293-2422 cor 16 32 22.56 -24 28 31.8           ~ 1193 1
4 NAME NGC 6334F (C) HII 17 20 53.45 -35 47 02.6           ~ 222 1
5 W 33a Y*O 18 14 39.56547 -17 52 02.2260           ~ 622 0
6 RAFGL 2136 Y*O 18 22 26.52888 -13 30 14.0400           ~ 276 0
7 RAFGL 2591 Y*O 20 29 24.8230 +40 11 19.590           ~ 606 0
8 NAME SH 2-140 IRS 1 Y*O 22 19 18.277 +63 18 45.82           ~ 195 0
9 [WBN74] NGC 7538 IRS 1 Y*O 23 13 45.318 +61 28 11.69           ~ 401 3
10 IRAS 23118+6110 Y*O 23 14 02.09473 +61 27 18.8460           ~ 367 0

To bookmark this query, right click on this link: simbad:objects in 2003A&A...412..133V and select 'bookmark this link' or equivalent in the popup menu


2023.02.01-20:08:59

© Université de Strasbourg/CNRS

    • Contact