On a spherical star system with a collapsed core
Exact solutions of Einstein's equations for a perfect fluid that describe the gravitational collapse of matter around a collapsed core are presented. The collapsed region grows monotonically until an absolute Schwarzschild horizon is formed. It is found that the minimum redshift of light emitted radially from the boundary of the system and received at infinity is approximately 4.62. These systems are expected to describe the very last stages in the gravitational collapse of a globular star cluster with a central collapsed core.
Glass, E. N.↗