Paper (*cross-listing*): gr-qc/0603055
Date: Tue, 14 Mar 2006 16:28:43 GMT (11kb)

Title: Radiation Pressure Supported Stars in Einstein Gravity

Authors: Abhas Mitra

Comments: 5 pages, submitted to MNRAS
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Even when we consider Newtonian stars, i.e., stars with surface gravitational
redshift, z << 1, it is well known that, theoretically, it is possible to have
stars, supported against self-gravity, almost entirely by radiation pressure.
However, such Newtonian stars must necessarily be supermassive. We point out
that this requirement for excessive large M, in Newtonian case, is a
consequence of the occurrence of low z<< 1. On the other hand, if we remove
such restrictions, and allow for possible occurrence of highly general
relativistic regime, z >> 1, we show that, it is possible to have radiation
pressure supported stars at arbitrary value of M. Since radiation pressure
supported stars necessarily radiate at the Eddington limit, in Einstein
gravity, they are never in strict hydrodynamical equilibrium. Further, it is
believed that sufficiently massive or dense objects undergo continued
gravitational collapse to the Black Hole stage characterized by z =infty. Thus,
late stages of Black Hole formation, by definition, will have, z >> 1, and
hence could be examples of quasi-stable general relativistic radiation pressure
supported stars. It is shown that the observed duration of such Eddington
limited radiation pressure dominates states is t ~ 5. 10^8 (1+z) yr. Thus, t
--> infty as Black Hole formation (z--> infty) would take place. Consequently,
such radiation pressure dominated extreme general relativistic stars become
Eternally Collapsing Objects and the BH state is preceded by such an eternal
radiation pressure supported phase.

\\ ( http://arXiv.org/abs/gr-qc/0603055 , 11kb)