Tidal Stablization of Neutron Stars and White Dwarfs

What happens to a neutron star or white dwarf near its maximum mass limit in a close binary orbit? Using an energy variational principle the tidal field reduces its central density, making it stable against radial collapse. For a cold white dwarf, the tidal field increases the maximum stable mass, but lowers the maximum central density by 30%. A white dwarf in a close binary may be more susceptible to the general relativistic instability than that with electron capture or pycronuclear reaction. We analyze radial stability of a neutron star using post-Newtonian approximation with a degenerate neutron gas equation of state. Tidal stablization implies that the neutron star in coalescing neutron star–neutron star or neutron star–black hole binaries does not collapse prior to merger or tidal disruption.