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Accueil du site > Évènements > Séminaires > Séminaires IRPHE > Archives IRPHE > 2016

Vendredi 19 Février 2016 / IRPHE

publié le , mis à jour le

Séminaire régulier IRPHE

Gravito-inertial modes in a differentially-rotating spherical shell and applications to stellar physics

Orateur : Giovanni Mirouh
Institut de Recherche en Astrophysique et en Planétologie, Toulouse

Résumé : Oscillation modes have been detected in a variety of celestial bodies and are the only way of probing the interior of stars. In stars with a high rotation rate, the properties of the detected modes are still badly-known, and their identification extremely challenging. These modes obey a partial differential equation of mixed type. We aim at improving our understanding of such modes by considering their propagation in a stably stratified spherical shell when the differential rotation due to baroclinicity is consistently taken into account. We studied the effects of a differential rotation on the low-frequency spectrum of these stars, which corresponds to gravito-inertial modes probing the deep layers of the stellar radiative zone. We solve the oscillation problem by (i) computing the paths of characteristics in the non-dissipative limit and (ii) solving the fully-dissipative eigenproblem numerically. I will present how the non-dissipative study allows us to determine the frequency range in which gravito-inertial modes can exist, predict the extent of the propagation domains, the appearance of attractors, wedge trapping, corotation resonances and critical latitudes. The simulations give us scaling laws for the damping rates, unveil modes unstable to a baroclinic instability, and show the existence of quasi-regular modes. I will also present applications to stars and finally discuss what diagnostics can be applied to more realistic stellar modes, and lead to accurate mode identification.

Date et lieu  : le Vendredi 19 Février 2016 à 14h00, salle de séminaire IRPHE