Wilhelmina Joseph, SBA, IAAT, Germany — December 8, 2025

The surface and atmosphere of the Sun are by no means quiet. They are bubbling with activity that includes surface dark spots that morph with time (sunspots) and explosions of energy and matter (flares and Coronal Mass Ejections). These phenomena result from magnetic field lines that protrude into the solar atmosphere from the surface, and twist and tangle as they do so.
These phenomena can be directly imaged only on the Sun. To study them on other stars, we must rely on indirect methods, such as analyzing spectra and light curves in various wavelengths in order to study their manifestations on different layers of the stellar atmosphere.
One type of star of particular interest is M dwarfs: small, cool but highly active stars that make up the majority of stars in our galaxy.  
These stars have also recently gained much attention as hosts of possibly habitable exoplanets.
In this talk, I present two of our projects: In the first, we characterized flares from a large sample of optical and X-ray light curves of M dwarfs taken from two large all-sky surveys. In the second, we test whether the corona of one particular M dwarf, AD Leo, is covered by the same kinds of magnetic structures that we see on the Sun.