Magnetism in Massive Stars - from the core to the surface

lundi 28 octobre 2019, par Kyle Auguston (AIM-CEA)

Jeudi 7 novembre 2019 à 14h00 , Lieu : Salle de conférence du bâtiment 17

Massive stars as with all stars possess convective regions, from the PMS to their explosive demise. These regions likely participate in vigorous dynamo action, leading to the construction of magnetic fields that can be in superequipartition with respect to the convection when in a rapidly rotating regime. Moreover, near surface regions of sufficiently massive stars can be convectively unstable, producing the so-called iron-bump convection zone. This region too will likely be running a dynamo. However, if it is threaded with fossil fields extant in the radiative regions of these stars which are of sufficient strength, it may be possible to quench the convection or shift it to very small scales, leading to weaker excitation of magneto-gravito-inertial waves in the radiative photospheric regions of these stars that manifest as macroturbulence. Yet establishing such strong fossil fields remains a largely murky process, where the complexities of the early evolutionary history of the star comes into play. Thus, this talk aims to cover the evolutionary history of massive stars in terms of their convective dynamos, their fossil field development, and the observational implications of such fields.