Composition of a Neutron Star’s Outer Crust

Abstract

In the field of astrophysics, the study of neutron stars is often conducted to improve nuclear models. This work evaluates the composition of the outer crust of a cold non-accreting neutron star. The standard approach to the outer crust is considered: nuclei are fixed in a Coulomb lattice surrounded by a Fermi gas of free and degenerate electrons. It is shown that considering electrons as ultra-relativistic is a reasonably accurate approach for our purposes (99.98%). The nuclear composition of the lattice is studied by minimizing the Gibbs energy per baryon using a custom Python program. Additionally, the effect of the variations of the Liquid Drop Mass formula parameters on the crust composition is explored by: 1) calibrating the parameters to different experimental masses; and 2) systematically changing the asymmetry parameter