Hydrostatic Equilibria for Rotating Stars: Toward Evolutions of Deformed Stars

We propose a scheme to obtain hydrostatic equilibria for deformed stars with rotation, and it is suitable for stellar-evolution calculations since it is based on mass coordinate. We present some hydrostatic equilibria, e.g. deformed stars with rigid rotation, cylindrical rotation, or shellular rotation. These results are not a priori, since the rotation laws are not assumed but obtained as a result of computations. We also check the instabilities of these structures with the Solberg-Hoiland criterion and the Bjerknes-Rosseland rules.