2004MNRAS.348L..23Z -
Mon. Not. R. Astron. Soc., 348, L23-L27 (2004/February-3)
Low-mass supernovae in the early Galactic halo: source of the double r/s-process enriched halo stars?
ZIJLSTRA A.A.
Abstract (from CDS):
Several stars at the low-metallicity extreme of the Galactic halo ([Fe/H]=-2.5) show strong enhancements of both s-process and r-process elements. The presence of s-process elements in main-sequence stars is explained via mass transfer from an asymptotic giant branch (AGB) companion star in a binary system. r-process elements originate in Type II supernovae and also require mass transfer. It is, however, unclear how pollution by both an AGB star and a supernova could have occurred. Here I show that the initial-final mass relation steepens at low metallicity, due to low mass-loss efficiency. This may cause the degenerate cores of low-Z, high-mass AGB stars to reach the Chandrasekhar mass, leading to an Iben & Renzini Type 1.5 supernova. Such supernovae can explain both the enhancement patterns and the metallicity dependence of the double-enhanced halo stars. Reduced mass-loss efficiency predicts more massive remnants in metal-poor globular clusters. The evidence for a high M/L population in the cores of globular clusters is briefly discussed.
Abstract Copyright:
2004 RAS
Journal keyword(s):
stars: AGB and post-AGB - stars: mass-loss
Simbad objects:
10
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