Solar models: influence of equation of state and opacity

Solar models through evolutionary phases of gravitational contraction, pre-main sequence and MS phases, up to current age 4.5 x 10(9) yr. and 4.57 x 10(9) yr., were studied adopting different prescriptions for the equation of state (EOS) and different opacity tables. Old EOS in Ezer's evolutionary code that we adopted in previous studies includes pressure ionization, and degeneracy of electrons. In the present study the EOS is obtained by minimization of the free energy (Mihalas et al. 1990, MHD), and the radiative opacity is derived from recent OPAL tables, implemented by the low temperature tables of Alexander & Ferguson. The results are compared with solar models we computed with different radiative opacities (Cox & Stewart 1970) and different EOS, as with models computed by other authors. Finally we provide the internal run of the thermodynamic quantities of our preferred solar model which possesses the following characteristics: age 4.50 x 10(9) yr., initial He abundance by mass 0.285, parameter of the mixing length alpha = 1.82, radius and temperature at the bottom of the convective envelope are R-b = 0.724 R. and T-b = 2.14 x 10(6) K, respectively.