  We investigate the role played by density inhomogeneities and dissipation on
the final outcome of collapse of a self-gravitating sphere. By imposing a
perturbative scheme on the thermodynamical variables and gravitational
potentials we track the evolution of the collapse process starting off with an
initially static perfect fluid sphere which is shear-free. The collapsing core
dissipates energy in the form of a radial heat flux with the exterior spacetime
being filled with a superposition of null energy and an anisotropic string
distribution. The ensuing dynamical process slowly evolves into a shear-like
regime with contributions from the heat flux and density fluctuations. We show
that the anisotropy due to the presence of the strings drives the stellar fluid
towards instability with this effect being enhanced by the density
inhomogeneity. An interesting and novel consequence of this collapse scenario
is the delay in the formation of the horizon.
