École Nationale Supérieure de
Techniques Avancées

Abstract

Among the B-type stars, there is a subcategory of stars called Be. These stars have the peculiarity of having an excretion disc at the equator and of rotating at speeds quite close to the critical speed. However, they never reach such a speed, so this cannot explain the presence of the disc. The hypothesis guiding this study is that the material excretion is due to the instability of certain eigenmodes of the surface gravity waves. This work is based on a numerical study to visualise the eigenmodes of the perturba- tions in the star and to observe potential bifurcations as a function of the different control parameters.