# Jean-Luc Movie: /NCSA1999/NeutronStars/Meudon_129_IVP/RhoBeta

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## Evolution of the Shift from Colliding Neutron Stars

Shown is the shift vectorfield (\vec\beta) and isosurfaces of the density at rho=10-5 (in geometric units, ~1/10 rhocentral ). The time unit T is given in solar mass units.

The shift vector field has to be chosen in an appropriate way to avoid coordinate singularities during evolution. As it is visible in this movie, the shift vector field moves according to the movements of the neutron stars, and the simulation nearly completes an entire orbit.

Without using a properly adjusted shift vectorfield, i.e. setting \vec\beta=0, like it is sufficient for static simulations, then the simulation code crashes after a few timesteps, because the coordinate distances between the grid points become too large.

 Simulation code: AEI , WashU Meudon Initial Data: Silvano Bonazzola, Eric Gourgoulhon and Jean-Alain Marck (see gr-qc/9810072 and gr-qc/9904040)

 ( Mpeg -