Thesis title
Magnetism in hot pulsating stars.
Composition of the jury
- Paola DI MATTEO Chair of the jury (LIRA, Observatoire de Paris-PSL)
- Conny AERTS Rapporteur (Institute of Astronomy, KU Leuven)
- Torsten BÖHM Rapporteur (IRAP, Université de Toulouse)
- Pascal PETIT Examiner (IRAP, Université de Toulouse)
- Victoria ANTOCHI Examiner (Danmarks Tekniske Universitet, Copenhagen)
- Coralie NEINER Thesis supervisor (LIRA, Observatoire de Paris-PSL)
- Claude CATALA Thesis supervisor (LIRA, Observatoire de Paris-PSL)
Abstract
β Cephei (β Cep) and slowly pulsating B (SPB) variables are the hottest pulsating stars on the main sequence. Understanding their internal structures and evolution are key for understanding evolution of the interstellar medium, and galaxies as a whole. We know that 10% of OBA stars host large scale surface magnetic fields, and that they have significant consequences on the lifetimes of these stars. In this PhD thesis, I perform an observational survey to identify β Cep and SPB variables with magnetic fields visible at their surface. Not only do I identify 10 new magnetic β Cep and SPB stars, but also among the expected OB sample, cases where the usually cooler δ Scuti (δ Sct) and γ Doradus (γ Dor) pulsations are able to exist in the presence of magnetic fields. This potentially constitutes the first example of a SPB/δ Sct hybrid star, and the first two magnetic γ Dor pulsators. I go on to develop the tools necessary to map the magnetic fields at the surface of pulsating stars with Zeeman-Doppler imaging, and demonstrate this on the star V2052 Oph. This work will lead to a better understanding of the modification of the internal structures of hot stars by magnetic fields, and consequently more detailed (magneto-)asteroseismic models.
