The effect of the recent O-17(p,alpha) 14N and O-18(p, alpha)N-15 fusion cross section measurements in the nucleosynthesis of AGB stars

The Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of the O-17(p, alpha)N-14 and O-18(p, alpha)N-15 fusion reactions and to extract the strengths of the resonances that more contribute to the reaction rates at astrophysical energies. Moreover, the strength of the 65 keV resonance in the O-17(p, alpha)N-14 reaction, measured by means of the THM, has been used to renormalize the corresponding resonance strength in the O-17 + p radiative capture channel. Since, proton-induced fusion reactions on O-17 and O-18 belong to the CNO cycle network for H-burning in stars, the new estimates of the cross sections have been introduced into calculations of Asymptotic giant branch (AGB) star nucleosynthesis to determine their impact on astrophysical environments. Results of nucleosynthesis calculations have been compared with geochemical analysis of "presolar" grains. These solids form in the cold and dusty envelopes that surround AGB stars and once that have been ejected by stellar winds, come to us as inclusions in meteorites providing invaluable benchmarks and constraints for our knowledge of fusion reactions in astrophysical environments.