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SAC Seminar - Günter Houdek: Main-sequence stars: mode physics and seismic diagnostics

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Wednesday 13 March 2013,  at 15:15 - 16:00

Speaker: Günter Houdek, Stellar Astrophysics Centre, Aarhus University

Title: Main-sequence stars: mode physics and seismic diagnostics

Abstract: The physics of solar-like oscillations determines their observable properties, i.e. frequencies, amplitudes, lifetimes, line asymmetries and phase relations. Measurements of these seismic quantities have been carried out with high precision in the Sun, and with the successfully launched space missions CoRoT and Kepler such seismic measurements are now being extended to low-degree solar-like oscillations in distant stars. I discuss the physical processes that determine the mode lifetimes of solar-like acoustic oscillations with application to Kepler observations and our current understanding of the mechanism that drives these oscillations to the observed amplitudes via their coupling with the turbulent velocity field in the outer convectively unstable stellar layers. I also discuss an asteroseismic diagnostic technique that allow us to measure some of the gross stellar properties from low-degree acoustic modes, and illustrate its application to Kepler stars. I conclude my presentation with a  discussion about mode stability of Delta Scuti stars with emphasis on the location of the classical instability strip.