Soutenance de thèse de Bram Buysschaert le jeudi 26 avril 2018

Titre de la thèse

Asteroseismology of magnetic massive stars

Directrices de thèse

Coralie Neiner (pôle Etoile du LESIA) et Conny Aerts (Université de Leuven, Belgique)

Abstract

Stable large-scale magnetic fields are detected at the surface of about 10% of main-sequence O, B, and A stars. These magnetic fields have a simple geometry - often a dipole inclined to the rotation axis - are stable over decades, and have strengths ranging from 100 G to more than 30 kG. Furthermore, theory and numerical simulations predict that the internal component of a strong large-scale magnetic field alters the interior structure of magentic OBA stars in comparison to their non-magnetic counterparts, thus also influences their evolution. Prior to this thesis, a detailed study of the interior physics of a magnetic star has only been carried out for the B star V2052 Oph, which yielded support for a small convective core overshooting layer. Following this result, I have utlised asteroseismology, the study of stellar pulsations, to probe the interior structure of other magnetic stars and searched for futher evidence to corroborate theoretical predictions for magnetic stars.

The first part of my thesis comprises the results of the identification of pulsating magnetic stars, by combining high-precision and long baseline space photometry with high-resolution ground-based optical spectropolarimetry. The second part of my thesis discusses the conclusions of coupling observations with stellar evolution and pulsation codes for modelling pulsating magnetic stars and extracting their interior physical properties.