EVOLUTION OF STARS OF LOW MASS

Abstract

Evolutionary sequences of models in the early and main sequence stages have been constructed for stars in the mass range [Formula: see text] with a composition X = 0.739, Z = 0.021. The general behavior of the evolutionary track in the Hertzsprung–Russell diagram is similar to that obtained for medium-mass stars. The [Formula: see text] star reaches the main sequence in 4 × 108 years, with a radiative core covering about half of the mass. The [Formula: see text] star develops a radiative core before reaching the main sequence in 8.5 × 108 years, but with the onset of thermonuclear reactions the energy generation is strong enough to cause the central radiative region of this star to become convective again. The [Formula: see text] star reaches the main sequence as a wholly convective star in 1.7 × 109 years. During the evolution of the [Formula: see text] star, the maximum central temperature attained is 4 × 106 °K, which is not sufficient to stabilize the star on the hydrogen-burning main sequence. Therefore, as contraction continues, the star contracts towards the white dwarf configuration.