This paper examines realistic configurations of anisotropic matter for spherical symmetry in modified gravity. With the Starobinsky f ( R ) = R + α R 2 model, the behavior of compact stars S A X J 1808.4 − 3658 and 4 U 1608 − 52 in the presence of an electromagnetic field. A core-envelope model is developed with polytropic and linear equation of state (EoS). The core, envelope, and Reissner Nordstr o ¨ m regions of compact stars match smoothly at the boundary. The graphs are plotted to discuss the physical behavior of density, pressure, mass, redshift, energy conditions, and compactification. To test stability of our model Tolman-Volkoff-Oppenheimer (TOV) equation and adiabatic index are presented graphically.
Mardan et al. (Sun,) studied this question.