The period-luminosity relation. IV. Intrinsic relations and reddenings for the Large Magellanic Cloud Cepheids.

Period, amplitude and the Wesenheit function are used to probe the intrinsic calibration of the period-luminosity relation for Cepheids with photoelectric B, V, photometry in the LMC. The relations are inverted to determine reddenings to the individual Cepheids, confirming earlier indications that detectable absorption exists within the LMC itself, and that longer-period Cepheids are systematically more heavily obscured. Amplitude is shown to vary systematically across the instability strip such that at all periods amplitude increases toward the cool edge.