Proposal: P01_09

Hans Bruntt, University of Sydney, Australia

Non-radial pulsation in overtone Cepheids

Abstract:

We propose to observe six Cepheid variables for the full duration of the Kepler mission. The highprecision data from Kepler will enable us to detect non-radial pulsations, which have only recently been discovered in overtone Cepheids. Amplitude variations, presumably caused by beating between radial and non-radial modes, have been detected over periods from a few days to over 100 years (Polaris). This may only hint at the size and duration of the amplitude variation which may be detected in Cepheids by Kepler. Characterizing this behavior and subsequent modelling will provide tests of the input physics of theoretical models, in the same way as the revision of opacities (relevant for both Cepheids and delta Scuti stars) that resulted from the well-known "Cepheid mass problem" two decades ago. We will further be looking for solar-like oscillations in the target stars.