Evolution of long-period, white-dwarf binaries: application to GRO J1744-28 and type Ia supernovae

Abstract

We calculated the evolution of long-period white dwarf binaries, by accounting for thermally unstable accretion during mass transfer. Under certain conditions we found that, the accretion rates onto the white dwarf during dwarf nova outbursts can be sufficiently high to allow steady nuclear burning of the accreted matter and growth of the white dwarf mass. If the Chandrasekhar mass is reached, the white dwarf may collapse to be a neutron star, or explode as a type Ia supernova. This scenario appears to account well for the formation of the bursting pulsar GRO J1744−28, and probably type Ia supernovae with delay times considerably longer than 1 Gyr.