Equilibrium configurations of relativistic white dwarfs

The Feynman-Metropolis-Teller treatment for compressed atoms is here recons idered in the framework of the relativistic generalised Fermi-Thomas model, obtained by Ruffini. Physical properties of a zero-temperature plasma is t hus investigated and the resulting equation of state, which keeps into acco unt quantum, relativistic and electromagnetic effects, is applied to the st udy of equilibrium configurations of relativistic white dwarfs. It is shown that numerical evaluation of such configuration leads, for the same centra l density rho (c), to smaller values of radius R and of mass M than in the classical works of Chandrasekhar and Salpeter, the deviations being most ma rked at the lowest densities (up to 30% from the Chandrasekhar model and 10 % from the Salpeter one for rho (c) similar to 10(6) g/cm(3), corresponding to M similar to 0.2M.) At high densities we considered the occurrence of i nverse beta-decays, whose effect is to introduce gravitational instability of the configurations. We consequently find the maximum mass of white dwarf s, which, for an oxygen and an iron WD, is, respectively, 1.365 M. and 1.06 3 M..