Dynamical instability of collapsing stars in the framework of Rn gravity

Abstract

To see the evolution of the physical variables at the surface of a star and to establish the range for an unstable system, we investigate the dynamical instability of a spherically symmetric collapsing star in the framework of Rn gravity. For this purpose, we have reformulated the dynamical equations in f(R) theory and perturb them in a specific manner. Under this perturbation scheme, quantities like energy density, pressure and heat flux are obtained and then used in the collapse equation which yield instability range for the ratio of specific heats Γ. Shear-free condition is applied and results are reduced to R2, $\frac{1}{R}$ and R gravity by choosing particular values of n in the f(R) model Rn