ON THE INSTABILITY OF DEFLAGRATION FRONTS IN WHITE-DWARFS

We discuss the stability of a deflagration front in white dwarfs in the context of burning mechanisms for Type Ia Supernovae. It is shown that the basic characteristics of the instability of the deflagration front are different from those of Rayleigh-Taylor instability, on which the deflagration models rely. In view of this, together with results from two-dimensional simulations, we argue that the deflagration model needs reconsideration, as Rayleigh-Taylor instability cannot explain the required high flame speed required for producing an explosion similar to Type Ia Supernovae. On the other hand, the same arguments imply that delayed detonation is acceptable and that the transition to detonation must occur in the very low density regime, where good agreement between observations and numerical results is obtained.