Neutron-Exposure Variations in MS and S Stars, and the Implications for s-Process Nucleosynthesis
Abstract
High-resolution, near-infrared spectra have been obtained for 34 stars of types MS and S along with 14 M giants used as comparison stars. Equivalent width measurements of spectral lines arising from the heavy s-process species La II and Nd II, relative to the lighter s-process species Y II, indicate a large range of neutron exposures in the MS and S stars. The indicated range of mean neutron exposures is approximately τ0 ≈ 0.1 - 0.6 mb-1. The solar system s-process distribution is characterized by τ0 = 0.26 mb-1.The overall enhancement of s-process elements observed in the MS and S stars indicates that they are substantial contributors to the Galactic production of s-process nuclei.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1987
- DOI:
- 10.1086/165601
- Bibcode:
- 1987ApJ...320..862S
- Keywords:
-
- M Stars;
- Neutron Irradiation;
- Nuclear Fusion;
- S Stars;
- Abundance;
- Asymptotic Giant Branch Stars;
- Giant Stars;
- Milky Way Galaxy;
- Neutron Sources;
- Spectral Line Width;
- Astrophysics;
- NUCLEOSYNTHESIS;
- STARS: ABUNDANCES;
- STARS: S-TYPE