  The independent dynamical variables of a collapsing homogeneous sphere of
dust are canonically quantised and coupled equations describing matter (dust)
and gravitation are obtained. The conditions for the validity of the adiabatic
(Born-Oppenheimer) and semiclassical approximations are derived. On neglecting
back-reaction effects, it is also shown that in the vicinity of the horizon and
inside the dust the Wightman function for a conformal scalar field coupled to a
monopole emitter is thermal at the characteristic Hawking temperature.
