Determining the surface tension of nuclei in the inner crust of neutron stars

Neutron stars are remnants of supernova that typically have a gravitational pull up to 10¹² m/s². Due to this gravitational pull, the mass of the neutron star (comparable to that of our sun), is compressed into a spherical shape with a radius of approximately 10 kilometers. Thus, neutron stars are observably the densest matter in the known universe, making them optimal for studying fundamental forces in extreme environments. Neutron stars have a solid outer crust made of nuclei arranged in a crystalline structure that gradually phases into a liquid core comprised primarily of neutrons. We have particular interest in the inner crust as it has neutrons external to the nuclei and can be examined with the compressible liquid drop model (CLDM). By fitting the surface energy parameters to nuclear data provided by scientists experimentally measuring properties of nuclei, we can find different parameterizations of nuclear matter specified by symmetry energy. With this distribution of symmetry energy parameters, we are then able to find the corresponding distributions of surface energy parameters. As a result, a uniform distribution of symmetry energy parameters allows for acquisition of the strength of the surface energy (sigma) and how that strength changes when the proton fraction decreases (sigma-delta). In conclusion, this research is to be able to find the surface energy parameters for any distribution of the symmetry energy parameters. Moving forward, these parameters will be used to determine properties of neutron stars related to the crust.