出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We review the main nucleosynthesis processes occurring in Asymptotic Giant Branch (AGB) Stars. They provide the production, in the He-rich layers above the degenerate C-O core, of intermediate-mass nuclei like 12C, 19F, 22Ne and of heavy, neutron-rich species (the s elements). They also include modifications to the abundances of elements up to Mg-Al, through proton captures occurring above the H-burning shell. The uncertainties still affecting these processes (especially in terms of mixing mechanisms and mass loss rates) are briefly outlined. We also discuss in some detail the recent discovery (from young open clusters) that the abundances of neutron capture elements have continued to increase after the formation of the Sun, contrary to expectations. This fact requires some modifications of the previously accepted scenario for slow neutron captures and indicates that important contributions to the s process must come from very low mass AGB stars (M 1.5 M).
