Electron Capture Supernovae From Close Binary Systems

Abstract

We present the first detailed study of the Electron Capture Supernova Channel (ECSN Channel) for a primary star in a close binary star system. Progenitors of ECSN occupy the lower end of the mass spectrum of supernovae progenitors and are thought to form the transition between white dwarfs progenitors and core collapse progenitors. The mass range for ECSN from close binary systems is thought to be wider than the range for single stars, because of the effects of mass transfer on the helium core. Using the MESA stellar evolution code we explored the parameter space of initial primary masses between 8 $M_\odot$ and 17 $M_\odot$, using a large grid of models. We find that the initial primary mass and the mass transfer evolution are important factors in the final fate of stars in this mass range. Mass transfer due to Roche Lobe overflow during and after carbon burning causes the core to cool down so that it avoids neon ignition, even in helium-free cores with masses up to 1.52 $M_\odot$, which in single stars would ignite neon. If the core is able to contract to high enough densities for electron captures to commence, we find that, for the adopted Ledoux convection criterion, the initial mass range for the primary to evolve into an ECSN is between 13.5 $M_\odot$ and 17.6 $M_\odot$. The mass ratio, initial period, and mass loss efficiency only marginally affect the predicted ranges.