The equilibrium configuration and the radial stability of white dwarfs composed of charged perfect fluid are investigated. These cases are analyzed through the results obtained from the solution of the hydrostatic equilibrium equation. We regard that the fluid pressure and the fluid energy density follow the relation of a fully degenerate electron gas. For the electric charge distribution in the object, we consider that it is centralized only close to the white dwarfs’ surfaces. We obtain larger and more massive white dwarfs when the total electric charge is increased. To appreciate the effects of the electric charge in the structure of the star, we found that it must be in the order of 1020[C] with which the electric field is about 1016[V/cm]. For white dwarfs with electric fields close to the Schwinger limit, we obtain masses around 2M⊙. We also found that in a system constituted by charged static equilibrium configurations, the maximum mass point found on it marks the onset of the instability. This indicates that the necessary and sufficient conditions to recognize regions constituted by stable and unstable equilibrium configurations against small radial perturbations are respectively dM/ dρc> 0 and dM/ dρc< 0.
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Acknowledgements Authors would like to thank Coordenação de A-perfeiçoamento de Pessoal de Nível Superior-CAPES and Fundação de Amparo à Pesquisa do Estado de São Paulo-FAPESP, under the thematic project 2013/26258-4, for the financial supports. GAC also thanks to Professors Dr. P. J. Pompeia and Dr. P. H. R. S. Moraes for discussion and support under the preparation of this work.
© 2018, The Author(s).