M. Shibata et al., STABILITY OF COALESCING BINARY STARS AGAINST GRAVITATIONAL COLLAPSE -HYDRODYNAMICAL SIMULATIONS - ART. NO. 023002, Physical review. D. Particles and fields, 5802(2), 1998, pp. 3002
We perform simulations of relativistic binary stars in post-Newtonian
gravity to investigate their dynamical stability prior to merger again
st gravitational collapse in a tidal field. In general, our equations
are only strictly accurate to first post-Newtonian order, but they rec
over full general relativity for spherical, static stars. We study bot
h corotational and irrotational binary configurations of identical sta
rs in circular orbits. We adopt a soft, adiabatic equation of state wi
th Gamma=1.4, for which the onset of instability occurs at a sufficien
tly small value of the compaction M/R that a post-Newtonian approximat
ion is quite accurate. For such a soft equation of state there is no i
nnermost stable circular orbit, so that we can study arbitrarily close
binaries. This choice still allows us to study all the qualitative fe
atures exhibited by any adiabatic equation of state regarding stabilit
y against gravitational collapse. We demonstrate that, independent of
the internal stellar velocity profile, the tidal field from a binary c
ompanion stabilizes a star against gravitational collapse. [S0556-2821
(98)07114-8].