The theoretical red edge of the RR Lyrae gap. II - Dependence of the red edge on luminosity and composition, and observational consequences

Abstract

The theoretical location of the red edge of the RR Lyrae Gap is computed for two luminosities and two compositions. An increase in luminosity or an increase in helium abundance decreases the effective temperature of the red edge. A comparison of the width of the instability strip with observations indicates that Y 0.3. The effects of convection on the light curves, velocity curves, pulsation periods, and overall structure of the models are small. Subject headings: convection - stars: abundances - stars: interiors - stars: pulsation - stars: RR Lyrae