Stellar Models with Isothermal Cores.

Abstract

This paper is devoted to the study of stellar models with isothermal cores. Two types of such con- figurations have been studied: (i) models with isothermal cores and polytropic envelopes (n = ~) and (2) models with isothermal cores and radiative point-source envelopes with a law of opacity K = K0pT35. The most important characteristic of these models is the existence of an upper limit to the fraction v of the total mass which can be contained in the core. For models of type 2, 7max 35%. Aiso it appears that, as v increases, the radius of the star first decreases to a minimum value and then increases. Further, the luminosity of the star is found to increase by about a factor 3 from the stage when it has no iso- thermal core to the stage when the core contains the maximum possible mass