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The effect of a density dependent bag constant on the structure of hot neutron star with a quark core

As we go from center toward the surface of a neutron star, the state of baryonic matter changes from the de-confined quark-gluon to a mixed phase of quark and hadronic matter, and a thin crust of hadronic matter. For the quark matter, within MIT bag model, the total energy density of the system is the kinetic energy for non-interacting quarks plus a bag constant. In this article first we have considered a density dependent bag constant obtained using the recent experimental results of CERN SPS on the formation of a quark-gluon plasma. For calculations of the hadron phase, we use the lowest order constrained variational method. The equation of state of mixed phase has been determined using Gibbs conditions. Finally, we have calculated the structure of a hot neutron star with quark core employing TOV equation. Our results show that a density dependent bag constant leads to a higher mass and lower radius for the hot neutron star with respect to the case in which we use a fixed bag constant.