Prof. Valery M Nakariakov
University of Warwick, United Kingdom
November 13, 2026 (Friday), 15:00
S4-917, Chien-Shiung Building

Abstract

Flaring energy releases observed in the atmospheres of the Sun and stars across all bands of the electromagnetic spectrum, as well as in particle fluxes, are produced by the conversion of magnetic energy stored in plasma into heat and the kinetic energy of non-thermal particles and bulk flows. Magnetic reconnection is commonly considered as the main mechanism of energy release in flares. However, a number of important details, such as the unexpectedly high reconnection rate, the partitioning and total amount of the released energy, and the triggering of flares, remain unclear. These questions are closely connected both with flare forecasting in the context of space weather, with the estimations of habitable zones of exoplanets, and with the issue of whether the Sun is capable of producing a devastating superflare similar to those observed on Sun-like stars.

        Often, light curves of the electromagnetic radiation generated in solar and stellar flares exhibit pronounced oscillatory patterns known as quasi-periodic pulsations (QPPs), with characteristic periods ranging from a fraction of a second to several tens of minutes. The QPP phenomenon is not accounted for in the standard flare model and is therefore expected to provide a natural metronome for constraining the characteristic timescales of physical processes in flares. In this talk, we summarise the current understanding of QPPs in solar and stellar flares, focusing on the possible physical mechanisms responsible for their generation, addressing the similarities between solar and stellar QPPs, and discussing future directions and key unanswered questions in this emerging field.