Helium and Carbon Detonations in Sub-Chandrasekhar White Dwarfs

There are many theoretical and observational reasons to consider several possible models for thermonuclear explosions of white dwarfs (WD), which may lead to inhomogeneous set of type Ia supernova (SNIa) events. The observed inhomogeneity in the set of events suggests variation within the set of progenitors, and may account for several different mechanisms (Phillips, 1993; Maza elal,1994; Hamuy, et al., 1994). Specifically, models for Sub-Chandrasekhar mass progenitors are interesting, as they avoid many of the difficulties encounter by the standard deflagration model (Nomoto, 1982a) or the delayed detonation model (Khokhlov, 1991a; Khokhlov, 1991b), for 1.4 M⊙ WDs, and at the same time introduce other challenging problems. One such mechanism is the Double Degenerate scenario,in which two WDs in a binary system coalesce (Iben Tutukov, 1984). Another mechanism, which is the main subject of this article, consists of hybrid progenitors in which a layer of helium acts as a detonator for an underlying carbon-oxygen core.