Inhomogeneous Stellar Models. I. Models with a Convective Core and a Discontinuity in the Chemical Composition.

A number of stellar models with a discontinuity in chemical composition have been computed through in detail. An arbitrary, but fixed, hydrogen-poor composition was used for the interior of all models, and a fixed hydrogen-rich composition was similarly used for all envelopes. The position in the star at which the change in chemical composition occurs was varied over a wide range. The computed models were found to cover well the observed red giants, as far as radii and luminosities are concerned. The masses of the theoretical red-giant models, however, fall systematically somewhat below the standard massluminosity relation-a circumstance not necessarily in discordance with observation.