Narrow Results

In this paper, we investigate gravastar configurations in which the interior of the compact object is modeled through a Chaplygin fluid. This is motivated by the fact that Chaplygin fluid and the associated exotic equation of state, have often been used as models for the dark energy sector. We derive the relativistic equations of the stellar structure for non-rotating configurations. A special focus is denoted in particular to the mass-radius function and the equation of state for the shell of the gravastars, for which we derive the analytical expressions.

The properties of neutron star at temperatures 5 MeV, 10 MeV and 15 MeV are calculated by solving Tolmann–Oppenheimer–Volkoff (TOV) equation. The required equation of state of pure neutron matter is obtained using density dependent Sussex interaction. It is observed that maximum stable mass of the star corresponds to minimum gravitational radius for a given equation of state. Just like the limiting mass, limiting value of redshift, moment of inertia, Kepler frequency as well as Kepler period are observed in case of the neutron star. It is found that the star become somewhat 'massive' and 'fat' at higher temperatures. With the increase in temperature the moment of inertia and Kepler rotational period increase but redshift decreases and Kepler frequency slows down. We also predict that there is a possibility of pion condensation in pure neutron matter.

For the accurate understanding of compact astrophysical objects, the Tolmann–Oppenheimer–Volkoff (TOV) equation has proved to be of great use. Nowadays, it has been derived in many alternative gravity theories, yielding the prediction of different macroscopic features for such compact objects. In this work, we apply the TOV equation of the energy–momentum–conserved version of the $f(R,T)$ gravity theory to strange quark stars. The $f(R,T)$ theory, with $f(R,T)$ being a generic function of the Ricci scalar $R$ and trace of the energy–momentum tensor $T$ to replace $R$ in the Einstein–Hilbert gravitational action, has shown to provide a very interesting alternative to the cosmological constant $\mathrm{\Lambda }$ in a cosmological scenario, particularly in the energy–momentum conserved case (a general $f(R,T)$ function does not conserve the energy–momentum tensor). Here, we impose the condition ${\nabla }^{\mu }{T}_{\mu \nu }=0$ to the astrophysical case, particularly the hydrostatic equilibrium of strange stars. We solve the TOV equation by taking into account linear equations of state to describe matter inside strange stars, such as $p=\omega \rho$ and $p=\omega (\rho -4B)$, known as the MIT bag model, with $p$ the pressure and $\rho$ the energy density of the star, $\omega$ constant and $B$ the bag constant.

In this paper, a well-behaved new model of anisotropic compact star in (3+1)-dimensional spacetime has been investigated in the background of Einstein’s general theory of relativity. The model has been developed by choosing $g_{rr}$ component as Krori–Barua (KB) ansatz [Krori and Barua in J. Phys. A, Math. Gen. 8 (1975) 508]. The field equations have been solved by a proper choice of the anisotropy factor which is physically reasonable and well behaved inside the stellar interior. Interior spacetime has been matched smoothly to the exterior Schwarzschild vacuum solution and it has also been depicted graphically. Model is free from all types of singularities and is in static equilibrium under different forces acting on the system. The stability of the model has been tested with the help of various conditions available in literature. The solution is compatible with observed masses and radii of a few compact stars like Vela X-1, 4U $1608-52$, PSR J$1614-2230$, LMC X$-4$, EXO $1785-248$.