The magnetic properties of massive stars are now known in quite some detail. About 7% of such stars show strong magnetic fields up to 1 T. The occurrence of strong magnetic fields correlates with likewise strong chemical abundance inhomogeneities on the surface of the stars. The origin of the strong magnetic fields is not known, stellar collisions being one of the leading hypotheses.
The winds of massive stars impact their environment in various ways. Surrounding gas is pressurised and pushed out, sometimes out to 100s of light years. This leads to the formation of superbubbles in the interstellar medium. Superbubbles play interesting roles in compressing other gas possibly leading to more star formation and also by transporting other gas into the halo of a galaxy, thus linking to the galaxy's overall evolution. Our group is strongly involved in observations and modelling of such superbubbles. One direction of this PhD would be to produce the first magnetised superbubble simulations that properly take into account the variety of magnetic field properties of the driving stars, based on existing code setups and know-how present in the team.
The other direction would be to model these magnetised superbubbles in the context of so-called super-massive stars. These so-far hypothetical stars might occur in very dense and massive star clusters and explain chemical peculiarities in such massive star clusters. The super-massive stars are thought to form via collisions, and would hence be expected to be strongly magnetised. If the chemical abundance inhomogeneities on their surface would be similar to the ones of normal magnetic massive stars, chemical inhomogeneities in the wind would arise which could be linked to the inhomogeneities in the star cluster.
In this project, the student would use the numerical tools present in the group to make the first predictions for superbubbles driven by magnetised massive stars. The project could go more in the direction of superbubbles from normal massive magnetised stars or exploring magnetised super-massive star superbubbles, depending on the interests of the student.