New Classes of Charged Spheroidal Models

New classes of exact solutions to the Einstein-Maxwell system is found in closed form by assuming that the hypersurface is spheroidal. This is achieved by choosing a particular form for the electric field intensity. A class of solution is found for all positive spheroidal parameter for a specific form of electric field intensity. In general, the condition of pressure isotropy reduces to a difference equation with variable, rational coefficients that can be solved. Consequently, an explicit solution in series form is found. By placing restrictions on the parameters, it is shown that the series terminates and there exist two classes of solutions in terms of elementary functions. These solutions contain the models found previously in the limit of vanishing charge. Solutions found are directly relating the spheroidal parameter and electric field intensity. Masses obtained are consistent with the previously reported experimental and theoretical studies describing strange stars. A physical analysis indicates that these models may be used to describe a charged sphere. 1. Introduction In recent years, there have been several investigations into the Einstein-Maxwell system of equations for static spherically symmetric gravitational fields with isotropic pressures in the presence of the electromagnetic field. In such study, regular interior spacetime is matched smoothly at the pressure free interface to the Reissner-Nordstrom exterior model. The models generated are useful to describe charged relativistic bodies with strong gravitational fields such as neutron stars. Gravitational collapse of a spherically symmetric distribution of matter to a point singularity may be avoided in the presence of electromagnetic field. In this situation, the gravitational attraction is counterbalanced by the repulsive Columbian force with the pressure gradient and, hence, charged fluids have a tendency to resist the gravitational collapse. This property persuades the researchers to work on charged perfect fluid distribution. Bonnor [1] has shown that charged dust solutions are expected to form a point like model of electron when its radius shrinks to zero. The presence of electromagnetic field affects the value of redshifts, luminosities, and maximum mass of a compact relativistic object (Ivanov [2], Sharma et al. [3]). Many exact solutions which satisfy the conditions for a physically acceptable charged relativistic sphere have been given by Ivanov [2], Thirukkanesh and Maharaj [4], and Gupta and Maurya [5], among others. Detailed studies of Sharma et al. [6] in cold compact