Theoretical Models for Classical Cepheids. II. Period‐Luminosity, Period‐Color, and Period‐Luminosity‐Color Relations

We present and discuss theoretical pulsational predictions concerning theproperties of Classical Cepheids. The computations have been performed forthree different chemical compositions taken as representative of Cepheids inthe Magellanic Clouds and in the Galaxy. The resulting PL relations aresignificantly dependent on metallicity, with the amplitude of the metallicityeffect decreasing at the longer wavelength. At variance with several empiricalsuggestions appeared in the literature, we find that at fixed period themetal-rich pulsators should be fainter than the metal-poor ones. TightPeriod-Luminosity-Color relations are derived for both visual and near-infraredphotometric bands. We present a preliminary use of our relations to evaluatethe distance modulus of the Magellanic Clouds.Comment: 33 pages, 23 postscript figures, accepted for publication on the Astrophysical Journa