The Tolman IV Space-time with Charge and a Cosmological Constant

The Tolman IV solution is one the very few exact solutions in general relativity that has found some physical relevance. It has been extensively used to model compact objects such as neutron stars and strange stars. In this paper, we generalise the Tolman IV solution by including charge and a cosmological constant. We find that the solution is physically acceptable for a range of values for central density and pressure. We investigate the spatial curvature and present conditions that lead to different spatial geometries. We also find that the charged fluid can be represented as a polytrope. Finally, we analyse the issue of internal trapping of circular geodesics and find that the solution allows for trapping of massive and charged particles but not of neutral null particles.