Intestellar 36S: a proble of s-process nucleosynthesis
-
R. Mauersberger
-
Steward Observatory,
The University of Arizona
- Tucson,
AZ 85721, U.S.A.
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C. Henkel
-
Max-Planck-Institut für Radioastronomie
- Auf dem Hügel 69, D-53121 Bonn, Germany
-
N. Langer
-
Max-Planck-Institut für Astrophysik
- Karl-Schwarzschild-Str. 1, D-85740 Garching, Germany
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Y.-N. Chin
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Institute of Astronomy & Astrophysics,
Academia Sinica
- P.O. Box 1-87 Nankang, 115 Taipei, Taiwan
- and
-
Radioastronomisches Institut der Universität Bonn
- Auf dem Hügel 71, D-53121 Bonn, Germany
Paper published in September 1996 by the Letters to Editor of
Astronomy and Astrophysics in vol. 313, pp. L1 - L4.
If you want to have a look at the complete paper please click
here (PostScript file of 904727 bytes) or
here (gzip-compressed PostScript file of 732710 bytes).
Abstract.
Sulfur possesses four stable isotopes, 32S, 33S,
34S, and 36S.
In the solar system, the abundance ratios are 95.02 : 0.75 : 4.21 : 0.021
(Anders & Grevesse 1989).
For the interstellar medium, Chin et al. (1996) determine abundance ratios of
24.4 (± 5.0) for 32S/34S, and 6.3 (± 1.0) for
34S/33S.
While no variation in the 34S/33S isotope ratio is found,
the 32S/34S ratio may increase with galactocentric radius.
In the local interstellar medium (ISM) 32S, 33S, and
34S abundance ratios are not drastically different from those in the
solar system.
For 36S, no interstellar data have been obtained so far.
32S, 33S, and 34S are mainly primary products
of oxygen-burning (Woosley et al. 1973; Chin et al. 1996); however, especially
the 34S yield retains a substantial sensitivity to the metallicity
(Woosley & Weaver 1995).
36S is thought to be a purely secondary isotope produced by neutron
captures on the primary sulfur seeds during helium- and carbon-burning
(Thielemann & Arnett 1985; Langer et al. 1989).
This isotope is, hence, formed in a process significally different from that of
the other sulfur or CNO isotopes accessible by means of molecular spectroscopy
at cm- and mm-wavelengths.
Any suggestion or comments please
e-mail to einmann@asiaa.sinica.edu.tw.
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