On the secular evolution of accreting white dwarfs and Type I supernovae

Abstract

The growth of a carbon-oxygen white dwarf is investigated within the framework of the general shell-flash theory of accreting white dwarfs. Account is taken of the envelope restructuring in response to the shell flash and to possible mass loss from the white dwarf. Estimates are given for the amount of helium accumulated between successive hydrogen shell flashes. Significant helium accumulation is possible for mass-accretion rates greater than 10 to the -9 solar masses per year. The results are discussed in the context of exploding white-dwarf models of Type I supernovae.