A semitheory for semiconvection

Semiconvection is the name given to a situation that arises in the evolution of large-mass main-sequence stars and lower-mass horizontal-branch stars, in which a layer forms where almost all of the heat flux is transported by radiation, but where slow convection is required to redistribute a stably stratified solute (e.g. helium). The main problem discussed in the article is the determination of the correct relationship between the solute distribution and the temperature gradient in the inhomogeneous layer. (J.R.)