Spherical Gravitational Collapse and Accretion - Exact General\n Relativistic Description

In this paper, we consider the problems of spherical gravitational collapse\nand accretion using a spherically symmetric, spatially homothetic spacetime,\nthat is, as an exact solution (cqg1) of the field equations of general\nrelativity. Properties of matter like its equation of state determine whether\nthe collapse becomes unstoppable or not since the spacetime under consideration\nadmits any equation of state for matter in it. We can therefore describe the\nformation of a semi-stable object here. {\\bf A black hole may form in the\nunstoppable gravitational collapse and/or accretion but only as an infinite\nred-shift surface that is, however, not a null hyper-surface.} Therefore,\nspherical, astrophysical black holes will always be of this type. This result\nwill have important implications for observational astrophysics and other\nconsiderations in General Relativity based on the conception of black hole as a\nnull hyper-surface.\n