2003/12/18 by A. A. Zijlstra, Albert A. Zijlstra · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2004.07552.x
published as Mon.Not.Roy.Astron.Soc. 348 (2004) L23 · MNRAS, Letters, accepted for publication. 5 pages, 2 Postscript figures
arxiv created 2003/12/18 · openalex publication_date 2004/02/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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.