Double detonations at the core-envelope boundary in Type Ia supernovae

An off-centre detonation propagating near the interface between a C-O core and a He envelope in a Type Ia supernova explosion is modelled as a steady two-dimensional similarity solution at a plane interface. We assume that in both regions the energy release occurs in an infinitely thin detonation, w hich produces material in nuclear statistical equilibrium (NSE) in He and i n nuclear statistical quasi-equilibrium in C-O. An alpha-network is then us ed to determine the effect of the associated rarefaction wave in the C-O on the final abundance of intermediate elements. We find that, although there is a significant effect, the rarefaction is not strong enough to quench th e reactions and prevent the C-O from burning to NSE.