We perform fully relativistic calculations of binary neutron stars in quasi-equilibrium circular orbits. We integrate Einstein's equations together with the relativistic equation of hydrostatic equilibrium to solve the initial value problem for equal-mass binaries of arbitrary separation. We construct sequences of constant rest mass and identify the innermost stable circular orbit and its angular velocity. We find that the quasi-equilibrium maximum allowed mass of a neutron star in a close binary is slightly larger than in isolation.
@article{arxiv.gr-qc/9704024,
title = {Binary Neutron Stars in General Relativity: Quasi-Equilibrium Models},
author = {T. W. Baumgarte and G. B. Cook and M. A. Scheel and S. L. Shapiro and S. A. Teukolsky},
journal= {arXiv preprint arXiv:gr-qc/9704024},
year = {2009}
}