Astrophysikalisches Kolloquium

The Department of Astrophysics and Geophysics at the Institute of Physics cordially invites you, as part of the Astrophysical Colloquium series, to a lecture by:

“Superflares on Sun-like stars and TRAPPIST-1”
Dr. Valeriy Vasilyev
Max Planck Institute for Solar System Research, Göttingen

Can superflares occur on the Sun, and if so, how often? One way to approach this is through a solar-stellar comparison. In this colloquium, I will present recent results from an analysis of 56450 Sun-like stars observed by the Kepler space telescope. Our analysis revises the occur-rence rate of superflares for Sun-like stars and finds it to be a factor of 50 higher than previously thought. Connections between superflares and solar energetic particle events are then exam-ined using a probabilistic approach. I will then discuss TRAPPIST-1, an ultracool dwarf and one of JWST's most frequently observed targets, where activity directly impacts exoplanet transmission spectroscopy. Using JWST observations, we find evidence for flare-driven trans-formations of the stellar surface, in particular the disappearance of dark magnetic features. JWST spectroscopic time series allow us to measure their spectra and estimate their temper-atures. Finally, we combine ~87 hours of JWST spectroscopy with K2 photometry to constrain a unified flare-frequency distribution spanning four decades in energy, providing fresh insight into which events dominate the long-term flare energy budget.

Time: Wednesday, 25^th March 2026 at 16:00 

Place: Bibliothek Experimentalphysik (0005-01-0122) 1. Stock, Universitätsplatz 5, 8010 Graz

Further details can be found in the attached invitation.
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Invitation