2017MNRAS.465.4817S

We investigate the impact of the new LUNA rate for the nuclear reaction ²²Ne(p, γ)²³Na on the chemical ejecta of intermediate-mass stars, with particular focus on the thermally pulsing asymptotic giant branch (TP-AGB) stars that experience hot-bottom burning. To this aim, we use the <monospace> PARSEC</monospace> and <monospace> COLIBRI</monospace> codes to compute the complete evolution, from the pre-main sequence up to the termination of the TP-AGB phase, of a set of stellar models with initial masses in the range 3.0-6.0 M_☉ and metallicities Z_i = 0.0005, 0.006 and 0.014. We find that the new LUNA measures have much reduced the nuclear uncertainties of the ²²Ne and ²³Na AGB ejecta that drop from factors of ≃10 to only a factor of few for the lowest metallicity models. Relying on the most recent estimations for the destruction rate of ²³Na, the uncertainties that still affect the ²²Ne and ²³Na AGB ejecta are mainly dominated by the evolutionary aspects (efficiency of mass-loss, third dredge-up, convection). Finally, we discuss how the LUNA results impact on the hypothesis that invokes massive AGB stars as the main agents of the observed O-Na anticorrelation in Galactic globular clusters. We derive quantitative indications on the efficiencies of key physical processes (mass-loss, third dredge-up, sodium destruction) in order to simultaneously reproduce both the Na-rich, O-poor extreme of the anticorrelation and the observational constraints on the CNO abundance.
Result. for the corresponding chemical ejecta are made publicly available.