The final stages of evolution of cold, mass-accreting white dwarfs

Abstract

The evolution of solid C + O white dwarf models upon mass accretion is calculated up to the point of either explosive thermonuclear ignition or gravitational collapse. It is shown that both explosions and 'quiet' collapses to a neutron star are possible for each of two different phase diagrams for high-density C + O mixtures. The ranges of initial masses and temperatures and of accretion rates leading to the different outcomes are determined. Problems concerning the chemical composition of the accreted matter and the effects of tidal dissipation are discussed.