The dependence of the evolution of Type Ia SN progenitors on the C-burning rate uncertainty and parameters of convective boundary mixing

Abstract

Evolution of a Type Ia supernova (SN Ia) progenitor requires formation of a CO white dwarf (WD), which implies a dependence on the C-burning rate (CBR). It can also be affected by the recently identified possibility of C-flame quenching by convective boundary mixing. We present first results of our study of the combined effect of these two potential sources of uncertainty on the SN Ia progenitor evolution. We consider the possibility that the CBR is higher than its currently recommended value by as much as a factor of 1000 if unidentified resonances are important, or that it is significantly lower because of the hindrance effect. For stellar models that assume the Schwarzschild boundary for convection, the maximum initial mass for the formation of CO WDs increases from Mi ≈ 5.5 M⊙ for the CBR factor of 1000 to Mi ≳ 7.0 M⊙ for the CBR factor of 0.01. For C-flame quenching models, hybrid C–O–Ne WDs form for a range of initial mass of ΔMi ≈ 1 M⊙, which increases a fraction of stars that form WDs capable of igniting C in a thermonuclear runaway. The most extreme case is found for the CBR factor of 0.1 that is supported by the hindrance model. This nuclear physics assumption, combined with C-flame quenching, leads to the formation of a hybrid C–O–Ne WD with a mass of 1.3 M⊙. Such WDs do not need to accrete much mass to reach the Chandrasekhar limit.