Neutronization during Type Ia Supernova Simmering

Abstract

Prior to the incineration of a white dwarf (WD) that makes a Type Ia supernova (SN Ia), the star ``simmers'' for ~1000 yr in a convecting, carbon-burning region. We have found that weak interactions during this time increase the neutron excess by an amount that depends on the total quantity of carbon burned prior to the explosion. This contribution is in addition to the metallicity (Z) dependent neutronization through the 22Ne abundance (as studied by Timmes, Brown, & Truran). The main consequence is that we expect a ``floor'' to the level of neutronization that dominates over the metallicity contribution when Z/Zsolar