We present an analysis of the origin of the Xe-S component implanted in mainstream presolar SiC grains considering two different scenarios: the first one assumes that xenon is implanted in the grains by cool and partly ionized winds during the AGB phase of carbon stars; the second one assumes that xenon is implanted in the subsequent planetary-nebula phase by hot and strong ionized winds from the central star. A comparison of AGB nucleosynthesis models predictions with measurements in bulk SiC grains is presented. This shows that 134Xe, an r-only isotope with a small s-contribution sensitive to the neutron channel branching at the unstable 133Xe, is a major indicator in favour of the first implantation scenario. This also constrains the mass and the metallicity of the parent AGB stars.
Memorie della Societa Astronomica Italiana
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