In this dissertation we consider spherically symmetric gravitational fields that arise in relativistic astrophysics and cosmology. We first present a general review of static spherically symmetric spacetimes. aand highlight a particular class of exact solutions of the Einstein-Maxwell system for charged spheres. In the case of shear-free spacetimes with heat flow, the integration of the system is reduced to solving the condition of pressure isotropy. This condition is a second order linear differential equation with variable coefficients. By choosing particular forms for the gravitational potentials, sev-eral classes of new solutions are generated. We regain known solutions corresponding to coniformal flatness when tidal forces are absent. We also consider expanding, accelerating and shearing models when the heat flux is not present. A new general class of models is found. This new class of shearing solutions contains the model of Maharaj et al (1993) when a parameter is set to zero. Our new solution does not contain a singularity at the stellar centre, and it is therefore useful in modelling the interior of stars. Finally, we demonstrate that the shearing models obtained by Markund and Bradley (1999) do not satisfy the Einstein field equations. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2007.

146 leaves : tables ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Mathematical Physics, 1979

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 95-98). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph.D.) -- University of Adelaide, Department of Mathematical Physics, 1979.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 247-250) Also available in print.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [202]-206).

Proefschrift--Utrecht. / "Conspectus" (in Latin) : p. [75]-76. "Stellingen" (2 leaves) inserted. "References" at end of each chapter.

Thesis (Ph. D.)--University of Hong Kong, 1998. / Includes bibliographical references.

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). "January 2009." Includes bibliographical references (leaves 125-131). Also available via the World Wide Web.

Proefschrift--Utrecht. / "Conspectus" (in Latin) : p. [75]-76. "Stellingen" (2 leaves) inserted. "References" at end of each chapter.