HIGH-PRECISION ROTATING NEUTRON-STAR MODELS .1. ANALYSIS OF NEUTRON-STAR PROPERTIES

A new and precise numerical code for computing equilibrium configurati ons of relativistic rotating bodies has been used to construct ''reali stic'' rotating neutron star models. Fourteen equations of state inclu ding recent dense matter models have been employed. Detailed compariso ns of our results with previous studies have been performed. Maximum m ass and maximum angular velocity models are presented and confronted w ith the constraints imposed by observed pulsars. A special emphasis is put on the construction of rotating configurations along sequences of constant baryon number, which may represent evolutionary sequences of rotating neutron stars. Two kinds of such sequences have been identif ied: the normal sequences which connect to the non-rotating limit and whose stars have a baryon number lower than the maximum one supported by static configurations and the supramassive sequences which do not c onnect to the non-rotating limit, its stars having a baryon number abo ve the maximum one supported by static configurations. A remarkable fe ature of supramassive stars is the phenomenon of spin-up by loss of an gular momentum which takes place just before the star enters the regim e of instability with respect to axisymmetric perturbations. In contra st, such a behavior has not been observed for normal stars.