Asymmetric Nuclear Matter and Neutron Star Properties

We calculate properties of neutron stars such as mass and radius using a relativistic Dirac-Brueckner-Hartree-Fock approach. Modern meson-exchange potential models are used to evaluate the $G$ matrix for asymmetric nuclear matter. For pure neutron matter we find the maximum mass to be $M_{max}\approx 2.4M_{\odot }$ for a radius $R\approx 12$ km, whereas with a proton fraction of 30% we find $M_{max}\approx 2.1M_{\odot }$ for a radius $R\approx 10.5$ km, close to the experimental values. The implications are discussed.