Equation of State of Hot Neutrino Opaque Interior Matter of Neutron Star

The equation of state of hot neutrino opaque interior matter of the neutron star and some of its properties such as the free energy, effective mass, adiabatic index, and temperature are calculated along both isothermal and isentropic paths with the AV18 and AV14 potentials using the lowest order constrained variational method. We have shown that the calculated equation of state with the AV18 potential is harder than with the AV14 potential. It is found that there is no phase transition in the hot neutrino opaque interior matter of the neutron star. We have shown that for all values of density and entropy, the adiabatic index of neutron star matter is greater than \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\frac{4}{3}$$ \end{document}. It is shown that our calculated equations of state obey the causality condition.