Self-consistent calculation of the nuclear composition in hot and dense stellar matter

Abstract

We investigate the mass fractions and in-medium properties of heavy nuclei in stellar matter at characteristic densities and temperatures for supernova (SN) explosions. The individual nuclei are described within the compressible liquid-drop model taking into account modifications of bulk, surface and Coulomb energies. The equilibrium properties of nuclei and the full ensemble of heavy nuclei are calculated self-consistently. It is found that heavy nuclei in the ensemble are either compressed or decompressed depending on the isospin asymmetry of the system. The compression or decompression has a little influence on the binding energies, total mass fractions and average mass numbers of heavy nuclei, although the equilibrium densities of individual nuclei themselves are changed appreciably above one hundredth of normal nuclear density. We find that nuclear structure in single nucleus approximation deviates from the actual one obtained in the multi-nucleus description, since the density of free nucleons is different between these two descriptions. This study indicates that a multi-nucleus description is required to realistically account for in-medium effects on the nuclear structure in supernova matter.