Hyper velocity stars are starts that travel at a much faster rate then the Galactic keplerian velocity. Each HVS is thought to have started out as a member of a binary, which approaches a black hole and was tidally torn apart. We will first calculate the distance from the black hole at which the rapture occurs. Suppose we have a symmetric binary, i.e. two equal mass stars (both of mass ) in a circular orbit around each other, separated by a distance . The distance at which the force between the two stars is the same order of magnitude as the shear from the black hole is
The difference in potential energies between the two stars is
Hence the terminal velocity of the escaping companion is
For two solar mass stars approaching a solar mass black hole, the terminal velocity can be 10 times higher than the escape velocity.