Effect of a single coordinate system of curvature on the properties of the boundary between R- and T-regions and the energy-momentum tensor

Gravitational collapse of a spherically symmetrical star is considered. On condition that there exist bound R- and T-regions in space-time, it is shown that in case of ideal liquid there is a surface dividing the R-region into two parts. Only one of them is covered by such a coordinate system of curvature where the Schwarzschild metric is outside the star. It is also shown that if the whole R-region is covered by such a coordinate system then the collapse has a number of extraordinary singularities: it is possible only for an unideal liquid, the boundary between the R- and T-regions is isotropic, some coordinate spheres in any spherically-symmetrical coordinate system expand before entering the T-region. A condition for the energy-momentum tensor on the boundary between the R- and T-regions is found