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SAC Seminar - Sebastien Salmon: Exploring the role of micro- and macro-physics on the seismic properties of main sequence B stars.

23.03.2015 | Louise Børsen-Koch

Dato ons 25 mar
Tid 14:15 15:15
Sted 1520-516

In this seminar, I will present how the physics adopted in stellar models impacts the seismic properties of stars, and reversely how asteroseismology can improve our knowledge on given physical processes.
I will start by investigating the recent detections of B-type candidate pulsators ( both beta Cephei and SPB stars) in the Magellanic Clouds. Such pulsators were not expected from a theoretical point of view, because these two galaxies present very low metallicities. I will show whether a peculiar chemical mixture or a possible underestimation of opacity could resolve that theoretical issue. In addition, I will discuss the question of the accuracy of stellar opacity in the case of the Sun.
I will then present what can we can learn from the asteroseismology of beta Cephei stars, based on a series of hare and hound exercises. Focus will be given on one hand on the physics adopted in the theoretical models, and on the other hand on the seismic observables that are needed. I will show in particular that the knowledge of the chemical mixture is of prime importance to determine the extent of the extra-mixing region close to the stellar convective core in these stars.
Finally, I will present my preliminary results on how rotation and mixing induced by rotation affect the oscillations of beta Cephei stars. Then, I will present how rotation can significantly affect the properties of SPB stars. As a consequence, fast rotating SPB stars might have been misidentified as a new class of variable stars in the a recent observational survey of the NGC 3766 cluster.

Offentligheden / Pressen, Medarbejdere, Studerende