Shell-model calculations of stellar weak interaction rates: II. Weak rates for nuclei in the mass range [formula omitted] in supernovae environments

Abstract

Based on large-scale shell-model calculations we have determined the electron capture, positron capture and beta-decay rates for more than 100 nuclei in the mass range A=45–65. The rates are given for densities ρY e=10 7 – 10 10 mol /cm 3 and temperatures T=10 9 – 10 10 K and hence are relevant for both types of supernovae (Type Ia and Type II). The shell-model electron capture rates are significantly smaller than currently assumed. For proton-to-baryon ratios Y e=0.42 –0.46 mol /g, the beta-decay rates are faster than the electron capture rates during the core collapse of a massive star.