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Period-colour and amplitude-colour relations in classical Cepheid variables II: the Galactic Cepheid model

S. Kanbur·C. Ngeow·R. Buchler
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Abstract

In this paper, we construct full amplitude non-linear hydrodynamical models of fundamental mode Galactic Cepheids and analyze the resulting theoretical period-colour and amplitude-colour relations at maximum, mean and minimum light. These theoretical relations match the general form of the observed relations well. This agreement is, to some extent, independent of the mass-luminosity relations used, pulsation code, numerical techniques, details of the input physics and methods to convert theoretical quantities, such as bolometric luminosity and temperature, to observational quantities, such as V band magnitudes or $(V-I)$ colours. We show that the period-colour and amplitude-colour properties of fundamental mode Galactic Cepheids with periods such that $\log (P)>0.8$ can be explained by a simple application of the Stefan-Boltzmann law and the interaction of the photosphere with the hydrogen ionization front. We discuss the implications of our results for explaining the behavior of Galactic Cepheid period-colour, and period-luminosity relations at mean light.

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S. Kanbur, C. Ngeow, R. Buchler. 2004-07-06. Period-colour and amplitude-colour relations in classical Cepheid variables II: the Galactic Cepheid model. https://doi.org/10.1111/j.1365-2966.2004.08183.x

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