The Laminar Flame Speedup by 22 Ne Enrichment in White Dwarf Supernovae

Carbon-oxygen white dwarfs contain neon-22 formed from alpha-captures ontonitrogen during core He burning in the progenitor star. In a white dwarf (typeIa) supernova, the neon-22 abundance determines, in part, the neutron-to-protonratio and hence the abundance of radioactive nickel-56 that powers thelightcurve. The neon-22 abundance also changes the burning rate and hence thelaminar flame speed. We tabulate the flame speedup for different initial carbonand neon-22 abundances and for a range of densities. This increase in thelaminar flame speed--about 30% for a neon-22 mass fraction of 6%--affects thedeflagration just after ignition near the center of the white dwarf, where thelaminar speed of the flame dominates over the buoyant rise, and in regions oflower density ~ 10^7 g/cm3 where a transition to distributed burning isconjectured to occur. The increase in flame speed will decrease the density ofany transition to distributed burning.