Binary helium dwarf supernovae

Abstract

The possibility of helium dwarf evolution to sufficiently high densities for violent helium ignition in low-massed binary systems is investigated. During accretional evolution the occurrence of thermonuclear runaway is found to be probable when the dwarf's mass approaches 1 solar mass, and steady-state discontinuous wave propagation considerations indicate that the dwarf is totally incinerated (i.e., its total mass burns to nuclear equilibrium) by a detonation wave. A numerical stellar dynamic investigation, including the full effects of nuclear statistical equilibrium and electron capture indicates total disruption for all reasonable dwarf central densities. For consistency with the cosmic element abundances, the conclusion of total disruption requires a low frequency for helium supernova events, implying that helium ignition in mass-exchanging binaries must occur at the lower densities of the relatively mild helium flash.