  We have computed quasiequilibrium sequences of synchronously rotating compact
binary star systems with constant rest masses. This computation has been
carried out by using the numerical scheme which is different from the scheme
based on the conformally flat assumption about the space. Stars are assumed to
be polytropes with polytropic indices of N=0.5, N=1.0, and N=1.5. Since we have
computed binary star sequences with a constant rest mass, they provide
approximate evolutionary tracks of binary star systems. For relatively stiff
equations of state (N < 1.0), there appear turning points along the
quasiequilibrium sequences plotted in the angular momentum -- angular velocity
plane. Consequently secular instability against exciting internal motion sets
in at those points. Qualitatively, these results agree with those of Baumgarte
et al. who employed the conformally flat condition. We further discuss the
effect of different equations of state and different strength of gravity by
introducing two kinds of dimensionless quantities which represent the angular
momentum and the angular velocity. Strength of gravity is renormalized in these
quantities so that the quantities are transformed to values around unity.
Therefore we can clearly see relations among quasiequilibrium sequences for a
wide variety of strength of gravity and for different compressibility.
