The Key problems of stellar evolution and nuclear physics for the s-process

s-過程に係る核物理と恒星進化の重要な問題

岩本 信之  

Iwamoto, Nobuyuki

The neutron capture reactions have an essential role on the nucleosynthesis heavier than iron. The production of nuclei by successive neutron capture reactions with the timescales longer than the lifetime of unstable nuclei are called an s-process and thus the nuclear reaction flow proceeds on stable nuclei. The main astrophysical sites of the s-process are the asymptotic giant branch phase of a low mass star and in the core He- and shell C-burning phases of massive stars. In both phases many evolutionary and nucleosynthetic calculations have been made with various stellar evolution codes. However, some problems which give a great impact on the s-process still remain. Especially, the s-process is affected by nuclear reaction rates of neutron- and alpha-induced reactions and material mixing which convection and rotation involve. Most of uncertainties of the s-process come from their uncertainties. In the presentation I will introduce the present status of nuclear reaction rates and material mixing mechanisms.