FERROMAGNETIC TRANSITION IN SUPERDENSE MATTER AND NEUTRON STARS

The conditions for dense nuclear matter to undergo a ferromagnetic transition are estimated, and shown to be applicable to neutron stars. The relativistic equation of state for interacting hard-core nucleons at T = 0 is developed, and used in integrating the general-relativistic hydrodynamic-equilibrium equation for the Schwarzschild metric. The calculation yields the boundaries between unmagnetized, partially magnetized and fully magnetized nuclear matter in the star, and also the total mass and the radius of the star. The latter two quantities, as functions of central density, are in qualitative agreement with other calculations of the equilibrium properties of a star composed of interacting nuclear matter. © 1969 Società Italiana di Fisica.