NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
SO and SO2 in mass-loss envelopes of red giants - Probes of nonequilibrium circumstellar chemistry and mass-loss ratesSO emission was searched for in one or more of four transitions toward 23 oxygen-rich red giant or supergiant stars and one S star, selected primarily on the basis of their nonmaser SiO emission. SO was detected in a total of 14 circumstellar envelopes, 13 of which are new detections. The circumstellar abundance of SO (and SO2) is significantly enhanced over the equilibrium value achieved in the photospheres of these stars. In general, the SO abundances are significantly larger than predicted by nonequilibrium circumstellar chemistry models. Sulfur cannot be significantly depleted onto circumstellar grains, and probably exists as H2S (and/or SH) in the inner regions of the envelopes. The SO rotational-level population in most circumstellar envelopes observed is characterized by excitation temperatures less than or approximately equal to 50 K. The circumstellar abundance of SO2 is comparable to, or larger than, that of SO, ruling out the 'large' value adopted for the unshielded photodissociation rate for SO2 in recent models.
Document ID
19920065510
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Sahai, Raghvendra
(Goteborg, University; Chalmers University of Technology, Sweden)
Wannier, Peter G.
(JPL Pasadena, CA, United States)
Date Acquired
August 15, 2013
Publication Date
July 20, 1992
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 394
Issue: 1, Ju
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
92A48134
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available