Stellar Magnetic Fields, Activity, and Exoplanets
Stars and exoplanets from space (Activity & planets - FFG funded through ASAP11): The study of magnetic fields is a cornerstone in present astrophysics, as magnetic fields play a key role in essentially all physical processes in space, in stellar and planetary formation and in the structure and evolution of planets and stars. Many aspects of magnetic fields and exoplanets ideally make use of observations from space; ESA has set up a sophisticated plan to advance the field, complemented by existing or recent missions providing comprehensive data archives, and in conjunction with ground-based observatories.
Within our research project, we study magnetic field morphologies in relation to stellar age, mass, and interior dynamics and the potential influence of these fields on the habitability of orbiting exoplanets. We focus on the central and cool regions of the Hertzsprung-Russel Diagram (HRD) covering young (pre-main sequence) stars, main sequence M-dwarfs, and solar-like stars from G- to mid F- and early A-spectral types as these presently are the most interesting and promising regions for the search for exoplanets. Magnetic fields significantly change their manifestation with stellar mass or stellar temperature. For example, the fields of M dwarfs are rather diverse, changing from simple, large-scale structures in fully convective mid-M dwarfs to more complex fields in earlier-type (more massive) M dwarfs; altogether, magnetic activity and the corresponding energetic radiation of M dwarfs decline much slower in time than in solar-type stars. The latter, of spectral type G and late-F, exhibit complex fields, variable on short time-scales, originating from a dynamo mechanism, while still slightly hotter F- (and A) stars either reveal globally structured, stable magnetic fields, or no (to date measurable) fields at all. These changing faces of stellar magnetism and the triggered activity phenomena most likely also cause a huge variety of conditions for - or against - the emergence of life on the surface of exoplanets - a centerpiece of present-day exoplanet research and key to upcoming exoplanet missions such as CHEOPS and PLATO.
Magnetic field studies are now benefiting from the enormous, combined progress of observational data quality and numerical simulations. Thus, we can apply sophisticated analysis techniques such as Bayesian photometric imaging (BPI) and Zeeman Doppler imaging (ZDI), and exploit excellent observational data obtained in space by, for example, the CoRoT and BRITE-C satellites, and data observed from ground with dedicated novel instrumentation such as ESPaDOnS, NARVAL, and HARPSpol.
This way we aim to significantly contribute to the explanation of theorigin, the evolution, and the pivotal role of magnetism in