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.