Speaker
Dr
Morgan Deal
(Observatoire de Paris)
Description
A number of Main Sequence B-type stars, like $\nu$ Eri, $\kappa$ Cen, a Car, $\kappa$ Vel, present oscillations which may be accounted for by opacity mechanisms, provided that the stellar opacity be larger than the standard computed one, at least in some specific layers. This has been studied by several authors, who computed "ad hoc" opacity profiles able to reproduce the observations. Here we show that atomic diffusion, which causes the elements to move selectively inside stars under the main effects of gravity and radiative accelerations, may be the reason for these opacities enhancements. The radiative accelerations on specific elements are the result of the photon absorption, which depend on the ionisation stage. For this reason, the elements accumulate in layers close to the region where they are the most important contributors to the global opacity. This increases the opacity at the right place in a natural way. We present preliminary results obtained for a 9.5 M$_\odot$ model.
Primary authors
Dr
Alain Hui-Bon-Hoa
(IRAP (OMP/CNRS/Univ. Toulouse))
Dr
Morgan Deal
(Observatoire de Paris)
Prof.
Sylvie VAUCLAIR
(IRAP (OMP/CNRS/Univ. Toulouse))
