Off-Center Deflagrations In Chandrasekhar Mass SN Ia Models

A series of two dimensional numerical simulations of explosive nuclear burning is presented for white dwarfs near the Chandraskhar mass. We assume that the burning begins as a slow deflagration front at or near the center of the star, and continues until the density in the burning regions has declined to about 10${}^7$ g cm${}^{-3}$, where the flame is essentially extinguished. We employ a novel numerical representation of the turbulent flame brush based upon ideas previously developed for modelling laboratory combustion and explore in some detail the sensitivity of the outcome to the manner in which burning is initiated. In particular, we simulate 1) a centrally ignited deflagration, 2) off-center ignition at a single point", and 3) simultaneous off-center ignition at five points". We find that the amount of ${}^{56}$Ni that is produced and other observable properties depend sensitively upon how the fuel is ignited.