Relativistic formalism for computation of irrotational binary stars in quasiequilibrium states

We present relativistic hydrostatic equations for obtaining irrotational binary neutron stars in quasiequilibrium states in the $3+1$ formalism. The equations derived here are different from those previously given by Bonazzola, Gourgoulhon, and Marck, and have a simpler and more tractable form for computation in numerical relativity. We also present hydrostatic equations for computation of equilibrium irrotational binary stars in the first post-Newtonian order.