Stellar Weak Interaction Rates and Energy Losses for fp-Shell Nuclei in the Proton-Neutron Quasiparticle Random-Phase Approximation

Abstract

Nuclear weak interaction rates for fp-shell nuclei in stellar matter and the associated energy losses are calculated using a modified form of proton-neutron quasiparticle RPA model with separable Gamow-Teller forces. The stellar weak rates are calculated over a wide range of densities (10 < \rho Y_{e} (gcm^{-3}) < 10^{11}) and temperatures (10^{7} < T(K) < 30 x 10^{9}). This is the first ever extensive compilation of weak interaction rates in stellar matter calculated over a wide temperature-density grid and over a larger mass range. The calculated capture and decay rates take into consideration the latest experimental energy levels and ft value compilations. We have calculated stellar weak interaction rates for a total of 619 nuclei in the mass range A = 40 to 100. These also include many important neutron-rich nuclei which play an important role in the evolution process of stellar collapse. This is our second paper in a series where we will be presenting our results on an abbreviated scale of temperature and density for the mass range A = 18 to 100. This paper contains the stellar weak rates in the mass range 40 to 60.