The role of ballast in the helium-shell flash

Calculations are presented of the evolutionary track of an asymptotic giant branch (AGB) star, after most of its envelope is consumed and it starts moving to the right in the Hertzsprung–Russell (HR) diagram. On looking for the conditions that may create a helium-shell flash at this stage, it is found that a necessary condition for the creation of a helium-shell flash at this stage is the presence of mass 'ballast' over the helium-burning shell. The effects of different amounts of such ballast are studied, and the detailed evolution of such a flash is presented.