We investigate the impact of the new LUNA rate for the nuclear reaction Ne-22(p, gamma) Na-23 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 PARSEC and COLIBRI codes to compute the complete evolution, from the premain sequence up to the termination of the TP-AGB phase, of a set of stellar models with initial masses in the range 3.0-6.0M(circle dot) 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 Ne-22 and Na-23 AGB ejecta that drop from factors of similar or equal to 10 to only a factor of few for the lowest metallicity models. Relying on the most recent estimations for the destruction rate of Na-23, the uncertainties that still affect the Ne-22 and Na-23 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 dredgeup, 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. Results for the corresponding chemical ejecta are made publicly available.
Origin of meteoritic stardust unveiled by a revised proton-capture rate of 17 O / Lugaro, M., Karakas, A.I., Bruno, C.G., Aliotta, M., Nittler, L.R., Bemmerer, D., Best, A., Boeltzig, A., Broggini, C., Caciolli, A., Cavanna, F., Ciani, G.F., Corvisiero, P., Davinson, T., Depalo, R., Di Leva, A., Elekes, Z., Ferraro, F., Formicola, A., Fã¼lã¶p, Z.S., et al.. - In: NATURE ASTRONOMY. - ISSN 2397-3366. - 1:2(2017), p. 0027. [10.1038/s41550-016-0027]
Origin of meteoritic stardust unveiled by a revised proton-capture rate of 17 O
Best, A.;Di Leva, A.;Imbriani, G.;
2017
Abstract
We investigate the impact of the new LUNA rate for the nuclear reaction Ne-22(p, gamma) Na-23 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 PARSEC and COLIBRI codes to compute the complete evolution, from the premain sequence up to the termination of the TP-AGB phase, of a set of stellar models with initial masses in the range 3.0-6.0M(circle dot) 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 Ne-22 and Na-23 AGB ejecta that drop from factors of similar or equal to 10 to only a factor of few for the lowest metallicity models. Relying on the most recent estimations for the destruction rate of Na-23, the uncertainties that still affect the Ne-22 and Na-23 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 dredgeup, 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. Results for the corresponding chemical ejecta are made publicly available.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
