Causal solutions for radiating stellar collapse

Recently, Govender et al. (Class. Quantum Grav. 15 (1998) 323) presented a simple model of radiating stellar collapse with a shear-free and non-accelerating interior matched to a Vaidya exterior. While highly simplified, this model did allow some insight into the temperature profile of the star during its evolution. However, the only exact causal solution for the temperature presented was in the case of constant mean collision time (sigma = 0) (with perturbative results for small sigma). We present two new exact causal solutions for the temperature equation and discuss the resulting temperature profiles of the collapsing star. We also provide similar results for the case of non-zero acceleration. In addition we provide non-constant mean collision time temperature solutions for the most general shearing line element with spherical symmetry. (C) 2001 Elsevier Science B.V. All rights reserved.