Investigation of burning in type Ia supernovae

Type Ia supernovae are important cosmological objects that have played a major role in determining the composition of the Universe. Despite four decades of studies, there is no complete understanding of the explosion mechanism. One of the main problems consists in describing the burning wave propagation through the presupernova, a white dwarf. It is well known from observations that an initially slow flame accelerates and transforms into detonation as it moves. The acceleration mechanism realized in supernovae is not yet known, but it is believed to occur through various instabilities. The Landau-Darrieus instability of a thin deflagration thermonuclear burning front propagating through the presupernova is investigated. Direct numerical simulations of burning by the level-set method are presented. Small perturbations at the front are shown to merge into one large cusp after some time. As a flame with limited sizes moves, this leads only to a slight increase in the velocity, which does not allow it to accelerate to the speed of sound.