On the surface tension and Coulomb energy of neutron-star matter

We briefly report the results from a study of the structure, the surface and the Coulomb energy of the core-crust transition layer of neutron stars with global charge neutrality. The results show that the surface tension is a power-law function of the baryon number density in the core region. We also present analyses of the influence of the gravitational field on the transition layer and the instability against Bohr-Wheeler surface deformations in the case of neutron stars obeying global charge neutrality. If the core-crust transition is assumed to occur at the nuclear density ρcore ≈ 2.7×1014 g cm−3, the instability sets the upper limit to the crust density, ρcrustcrit ≈ 1.2×1014 g cm−3.