An Analytical Estimate of Values of Pressure and Temperature at the Boundary of a Convective Core

Trajče Angelov

We consider a model of star which is divided in two regions: the "internal" and the "external" one. The model is spherical1y symmetric, in hydrostatic equilibrium, with an equation of state for a perfect gas with $\mu$ = const. The dimensionless integral $I_{\sigma, \nu}$ (Chandrasekhar, 1939) is considered in function of its upper limit, which determines the depth of the region. Analytical estimates are given for $I_{\sigma, \nu}$, \={P} and \={T}, for the "internal" and "external" region and the values for P and T at their boundary. Particularly, for the models of the zero main-sequence stars, with $4 \leq M_{0} \leq 16$, P and T are estimated at the boundary of the convective core.