The AGB star nucleosynthesis in the light of the recent ~(17)O(p,α)~(14)N and ~(18)O(p,α)~(15)N reaction rate determinations

摘要

Presolar grains form in the cold and dusty envelopes of Asymptotic Giant Branch (AGB) stars. These solides, once that have been ejected by stellar winds, come to us as inclusions in meteorites providing invaluable benchmarks and constraints for our knowledge of low temeperature H-burning in stars. The Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of the ~(17)O(p,α)~(14)N and ~(18)O(p,α)~(15)N reactions. Moreover, the strength of the 65 keV resonance in the ~(17)O(p,α)~(14)N reaction, measured by means of the THM, has been used to renormalize the corresponding resonance strength in the ~(17)O+p radiative capture channel. The new estimates of the reaction rates have been introduced into calculations of AGB star nucleosynthesis and the results have been compared with geochemical analysis of "presolar" grains to determine their impact on astrophysical environments.