EVOLUTION OF PROGENITORS FOR ELECTRON CAPTURE SUPERNOVAE

We provide progenitor models for electron capture supernovae (ECSNe) with detailed evolutionary calculation. We include minor electron capture nuclei using a large nuclear reaction network with updated reaction rates. For electron captures, the Coulomb correction on the rates is treated and contribution of neutron-rich nuclei is taken into account in the nuclear statistical equilibrium (NSE) composition. We calculate the evolution of the most massive super asymptotic giant branch stars and show that these stars undergo off-center carbon burnings and form ONe cores at the center. These cores get heavier up to the critical mass of 1.367 Msun and keep contracting even after the initiation of O+Ne deflagration. Though inclusion of minor electron capture nuclei causes convective URCA process at the contraction phase, such process will have minor effect on the evolution. On the other hand, electron captures by neutron-rich nuclei in the NSE region have more significant effect. Also, we discuss the uniqueness of the critical core mass for ECSNe and the effect of mass loss on the plausibility of our models for ECSN progenitors.