A versatile numerical method for obtaining structures of rapidly rotating baroclinic stars: self-consistent and systematic solutions with shellular-type rotation

Abstract

This paper develops a novel numerical method for obtaining structures of rapidly rotating stars based on a self-consistent field scheme. The solution is obtained iteratively. Both rapidly rotating barotropic and baroclinic equilibrium states are calculated self-consistently using this method. Two types of rotating baroclinic stars are investigated by changing the isentropic surfaces inside the star. Solution sequences of these are calculated systematically and critical rotation models beyond which no rotating equilibrium state exists are also obtained. All of these rotating baroclinic stars satisfy necessarily the Bjerknes-Rosseland rules. Self-consistent solutions of baro-clinic stars with shellular-type rotation are successfully obtained where the isentropic surfaces are oblate and the surface temperature is hotter at the poles than at the equator if it is assumed that the star is an ideal gas star. These are the first self-consistent and systematic solutions of rapidly rotating baroclinic stars with shellular-type rotations. Since they satisfy the stability criterion due to their rapid rotation, these rotating baroclinic stars would be dynamically stable. This novel numerical method and the solutions of the rapidly rotating baroclinic stars will be useful for investigating stellar evolution with rapid rotations.