Rr Lyrae – Theory Vs Observation

The luminosities, effective temperatures and metallicities that are derived empirically by Kovács and Jurcsik from the light curves of a large number of globular cluster and field RRab and RRc stars are compared to theoretical RR Lyrae models. The strong luminosity dependence of the empirical blue and red edges (LogL vs. LogTeff diagram) is in disagreement with that of both radiative and convective models. A reexamination of the theoretical uncertainties in the modelling leads us to conclude that the disagreement is irreconcilable. Subject headings: stars: variable, stars: oscillations, stars: RR Lyrae, stars: horizontal-branch, globular clusters, stars: fundamental parameters, stars; abundances, stars: distances Konkoly Observatory, Budapest, HUNGARY; [email protected] Physics Department, University of Florida, Gainesville, FL, USA; [email protected], [email protected]