Nuclear statistical equilibrium and the iron peak

The equations governing the abundance distribution of the nuclear species (atomic nuclei) under conditions of statistical equilibrium of the strong nuclear interaction are rederived and discussed. An algorithm for their solution on a computer is presented, giving abundance distributions as a function of temperature, density and overall neutron-proton ratio. A computer search of nuclear species abundance distributions and mixtures of two distributions is carried out in an attempt to match equilibrium distributions, after weak interaction decay, of certain "iron peak" species to their observed solar system distributions. A mixture is found which reproduces the solar system abundance distribution of Fe 54,56,57,58. Ninety-nine percent of the Fe56 is produced in nuclear statistical equilibrium as Ni56, lending hope to the proposed observation by gamma ray astronomy of the decay of Ni56 to Fe56 following a supernova event