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Lithium abundances in AGB stars and a new estimate for the 7Be life-time

Authors: 
S. Palmerini
M. Busso
S. Simonucci
S. Taioli
Abstract: 
In most cases RGB and AGB stars with M< 2M⊙ destroy Li (which is instead synthesized trough electron-captures on 7Be). This occurs through the combined operation of mixing processes and proton captures, when H-burning operates close to the envelope. Observed Li abundances are however difficult to explain, as they cover a wide spread. Various uncertainties affect model attempts, but so far the largest one concerns the processes of bound and free e- captures on 7Be, hence its life-time, whose known estimates are valid only for solar conditions. RGB and AGB stages have temperatures and densities below the envelope covering a wide range and differing from solar by up to a factor of five for T and up to five orders of magnitudes for ρ, hence extrapolations are unreliable. Recently, we presented an estimate of the 7Be half-life based on a fully quantistic method that goes beyond the Debye-Huckel approximation. Here we discuss its consequences on Li nucleosynthesis in low mass AGB stars.
Date of publication: 
10/02/2016
Published in: 
J. Phys.: Conf. Ser. 665, 012014 (2016)