Durchmischungsprozesse in Massereichen Sternen und Ihr Einfluss Auf Stellare Entwicklung und Nukleosynthese (Intermixing Processes in Massive Stars and Their Influence on Stellar Evolution and Nucleosynthesis)

摘要

The influence of several mixing processes due to convective overshooting and semiconvection in the interior of massive single stars on their evolution as well as on the nucleosynthesis products was investigated, mainly during the phase of central helium burning. All the calculations were performed using a stellar evolution program that also determines the dependence of nucleosynthesis on the mixing processes. The theoretical uncertainties were limited using results of observations. Core growth due to overshooting was determined. Semiconvection and overshooting substantially affect the evolution of mass-losing, helium-burning stars, as well as the stellar nucleosynthesis. The hydrostatic s-process nucleosynthesis was consistently calculated in realistic stellar models. Overshooting in very massive stars is found to be an inefficient process.