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SAC Seminar - Rhita-Maria Ouazzani: Non-perturbative effects of rotation on stellar pulsations

09.07.2013 | Brigitte Christina Harke Henderson

Dato ons 10 jul
Tid 15:15 16:00
Sted 1525-323

Speaker: Rhita-Maria Ouazzani, IAS, Université Paris Sud, Centre universitaire d’Orsay, 91405 ORSAY, France

Title: Non-perturbative effects of rotation on stellar pulsations

Abstract:

Stellar rotation plays a key role in the evolution of stars. It causes mixing of chemical elements and transport of angular momentum which will strongly determine the star's history. Asteroseismology is the most efficient observational mean to get information about stellar interiors by measuring magnitude variability induced by seismic waves at the stellar

surface. The space missions CoRoT and Kepler provide high quality data that allow us to test the transport of angular momentum in stars by the seismic determination of the internal rotation profile. But rotation also impacts these seismic pulsations: the centrifugal force distorts the resonant cavity while the Coriolis force modifies the fluid dynamics. When a star rotates slowly, a perturbative approach gives satisfying results for the computations of the rotational impact on oscillations. But for rapidly surface rotating stars --as delta Scuti stars--, or for rapidly core rotating stars that exhibit long period oscillations --as red giant stars-- only the non-perturbative approach is suitable in order to get accurate information about the stellar structure from asteroseismology. Based on the non-perturbative approach I developped in the ACOR code, I establish the limits of the traditional approach and investigate the oscillation spectra when the validity does not hold, for two types of stars: delta Scuti stars and red giants

Institut for Fysik og Astronomi, Medarbejdere, Offentligheden / Pressen