We discuss numerical solutions of Einstein's field equation describing stat
ic, spherically symmetric conglomerations of a photon gas. These equations
imply a back reaction of the metric on the energy density of the photon gas
according to Tolman's equation. The 3-fold of solutions corresponds to a c
lass of physically different solutions which is parameterized by only two q
uantities, i.e. mass and surface temperature. The energy density is typical
ly concentrated on a shell because the center contains a repelling singular
ity, which can, however, not be reached by timelike geodesics and only by r
adial null geodesics. The physical relevance-of these solutions is complete
ly open, although their existence may raise some doubts w.r.t. the stabilit
y of black holes.