  We model the gravitational behaviour of a radiating star when the exterior
geometry is the generalised Vaidya spacetime. The interior matter distribution
is shear-free and undergoing radial heat flow. The exterior energy momentum
tensor is a superposition of a null fluid and a string fluid. An analysis of
the junction conditions at the stellar surface shows that the pressure at the
boundary depends on the interior heat flux and the exterior string density. The
results for a relativistic radiating star undergoing nonadiabatic collapse are
obtained as a special case. For a particular model we demonstrate that the
radiating fluid sphere collapses without the appearance of the horizon at the
boundary.
