Solar-Stellar Connections

Dr. Petri Käpylä

Solar physics allows research on physical processes that are relevant for many other stars, such as large-scale magnetism manifested by the solar cycle and small-scale magnetism of the quiet Sun. Given the high detail of solar observations, the Sun often serves as a paradigm. However, the Sun alone is a single data point and generalizing the results to the bigger picture of stellar evolution and magnetism requires viewing the Sun as a star and the studying the connections of solar activity with that of other stars. Understanding solar and stellar magnetism and activity driven by dynamos and MHD processes and their influence on the interplanetary environment and planets is another motivation for the research on solar-stellar connections.

We study magnetism of the Sun observationally at a high spatial resolution and in the context of stellar using for example Kepler data. In addition, we make local and global ab initio MHD simulations of dynamos of the Sun and other stars to find out the fundamental physical processes driving stellar activity. Our goal is to understand the origin, structure and evolution of  magnetic fields in active cool stars with outer convection zones, such as the Sun and including low-mass, fully convective dwarfs. This research is also connected to the influence of stellar radiation and activity on atmospheres and habitability of exoplanets. Hence, our research aims to address the following questions:

• Which processes drive solar and stellar magnetism on local and global scales?
• Is the solar dynamo also representative of stars with a higher activity?
• How do stars influence the planetary environment, atmsopheres and habitability?