A detailed recalculation of the spectrum of radiation emitted during   gravitational collapse of a spherically symmetric star
  We address the question of radiation emitted from a collapsing star. We consider the simple model of a spherical star consisting of pressure-free dust and we derive the emission spectrum via a systematic asymptotic expansion of the complete Bogolubov amplitude. We present a review of standard features of the problem and we point out certain inconsistencies in previous derivations. 
Alex Calogeracos