  This article describes a comparison of two calculations of the merger of a
binary neutron star (NS) system which is initially within the tidal instability
as described by Rasio and Shapiro. The same initial data is used with one
simulation involving a purely Newtonian evolution of the Euler equations for
compressible fluids and another similarly evolved except there is an inclusion
of a gravitational radiation reaction (GRR) term at the 2.5 Post-Newtonian (PN)
order as prescribed by Blanchet, Damour, and Schafer. The inclusion of GRR is
to allow an approximation of the full relativistic effect which forces the
inspiral of binary systems. The initial data is identical at the start of each
evolution and only the inclusion of the 2.5PN term differs in the evolutions.
We chose two co-rotating, gamma=2 polytropic stars with masses 1.4M_Solar,
radii R=9.56km and central densities of 2.5E15 g/cm3. The initial binary
separation is 2.9R, inside the region where the dynamical tidal instability has
been shown to cause the merger of the two stars. Comparisons between measured
quantities will indicate a substantial difference between the two evolutions.
It will be shown that the effect of GRR on the dynamics of the merger is
significant.
