The dependency of the Cepheid Period‐Luminosity Relation on chemical composition at different wavelengths is assessed via direct detailed abundance analysis of Galactic and Magellanic Cepheids, as derived from high resolution, high signal‐to‐noise spectra. Our measurements span one order of magnitude in iron content and allow to rule out at the ∼9 sigma level the universality of the Period‐Luminosity Relation in the V band, with metal rich stars being fainter than metal poor ones by ∼0.3 mag. The dependency is less pronounced in the K band. Its magnitude and statistical significance decisively depend on detailed distance measurements to individual stars, as inferred via the Infrared Surface Brightness Method.

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