Petri Käpylä is welcomed as new astrophysics professor

Petri Käpylä was born in Oulainen, Finland, and lived his childhood and youth in remote countryside with no light pollution. The starry skies in the long winter nights sparked an interest in astronomy in him. Petri was also interested in computers and computing from a very young age. These lifelong interests first led to a career in astrophysics and now to his appointment as Professor of Computational Astrophysics at the University of Graz.

Petri obtained a Master's degree in astronomy in the University of Oulu in Finland on numerical simulations of accretion disks. Thereafter, his research interests shifted predominantly to the field of stellar astrophysics and especially to the problems of convection and dynamos in solar-like stars. Petri received his PhD from the University of Helsinki in 2006 on comparisons between 3D stellar convection simulations and mean-field theories of hydrodynamics and magnetohydrodynamics. Most of the research for the PhD thesis was done at the Kiepenheuer-Institut für Sonnenphysik (KIS), in Freiburg, Germany.

Thereafter, Petri had postdoc and junior group leader positions at the Nordic Institute for Theoretical Physics (NORDITA) in Stockholm, Sweden, and in the University of Helsinki, respectively. After appointments as a senior scientist at Aalto University in Espoo, Finland, and at the Leibniz-Institute for Astrophysics (AIP) in Potsdam, Germany, Petri obtained a DFG Heisenberg Fellowship to work at the University of Göttingen. Since 2023, he has been a group leader and scientist with tenure at the Institute for Solar Physics (KIS) in Freiburg.

Much of Petri's recent research has concentrated on an issue known in the field as the "convective conundrum", which is the discrepancy between current global 3D simulations and large-scale observables in the Sun. The latter include the non-uniform rotation and cyclic magnetic activity of the Sun. The core of the issue is correct modelling of flows in the solar envelope. This led to the ERC Advanced Grant "New Paradigm of Stellar Convection (NEOCON)" that Petri will be leading in Graz. The project explores the ideas that convection in Sun-like stars is driven by surface cooling, leading to highly non-local cool entropy rain, and that magnetism has a much stronger effect on large-scale convective flows than previously thought. Both of these ideas have the potential to lead to a radically new perspective to stellar convection with far-reaching consequences in other fields of astrophysics. The group of computational astrophysics will work intensively on implementing the new ideas of convection in numerical simulations over the next years.

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