Stellar weak interaction rates for intermediate-mass nuclei. II - A = 21 to A = 60

Astrophysical electron and positron emission, continuum electron and positron capture rates, and associated neutrino energy loss rates are calculated for free nucleons and 226 nuclei with masses between A = 21 and 60. Where available, measured nuclear level information and matrix elements are used. Simple shell model arguments are used in estimating Gamow-Teller sum rules and collective state resonance excitation energies. The discrete state contribution to the rates, dominated by experimental information and the Fermi transitions, determines the nuclear rates in the regime of temperatures and densities that is characteristic of the hydrostatic phases of presupernova stellar evolution. At the higher temperatures and densities characteristic of the supernova collapse phase, the nuclear rates are dominated by the Gamow-Teller and Fermi collective resonance contributions. Also included is the effect of neutron shell closure blocking of electron capture on neutron-rich nuclei.