Preliminary results on detailed helium shell flash calculations

Preliminary results are reported for detailed calculations of ten successive helium flashes in Population I stars of 3 and 3.3 solar masses. The calculations have been conducted to determine whether an inner-shell convection zone that is driven outward from the center of the helium-burning shell by the flashes can penetrate into the hydrogen-rich zones of a star. Based on the present incomplete calculations, the process of flash evolution is outlined, the relationship between core mass and interflash period is described together with the relationship between core mass and intershell mass, and nucleosynthesis during helium-shell flash burning is considered. The results thus far indicate that the flashes increase in strength and consist of up to five subcomponents, the mass of the degenerate carbon-oxygen core may determine the interflash period as well as the intershell mass, and that helium flash burning produces mostly C-12 and a small amount of O-16.