A magnetic avalanche as the central engine powering a solar flare

¹ Max-Planck-Institut für Sonnensystemforschung 37077 Göttingen, Germany
² School of Information and Physical Sciences, University of Newcastle Callaghan NSW 2308, Australia
³ School of Mathematics and Statistics, University of St Andrews St Andrews KY16 9SS, UK
⁴ Solar-Terrestrial Centre of Excellence, Solar Influences Data analysis Centre, Royal Observatory of Belgium 1180 Brussels, Belgium
⁵ Skobeltsyn Institute of Nuclear Physics, Moscow State University 119991 Moscow, Russia
⁶ Space Sciences Laboratory University of California Berkeley CA 94720, USA
⁷ University of Applied Sciences and Arts Northwestern Switzerland CH-5210 Windisch, Switzerland
⁸ Institut für Sonnenphysik (KIS) Georges-Köhler-Allee 401a 79110 Freiburg, Germany
⁹ RAL Space, UKRI STFC Rutherford Appleton Laboratory Didcot OX11 0QX, UK
¹⁰ University of Catania, Astrophysics Section, Dept. of Physics and Astronomy Via S. Sofia 78 95123 Catania, Italy
¹¹ Université Paris-Saclay, CNRS, Institut d’astrophysique spatiale 91405 Orsay, France
¹² Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center 7260 Davos Dorf, Switzerland
¹³ Die Eidgenössische Technische Hochschule Zürich 8093 Zürich, Switzerland
¹⁴ European Space Agency (ESA), European Space Research and Technology Centre (ESTEC) PO Box 299 2200 AG Noordwijk, The Netherlands

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 15 September 2025
Accepted: 12 November 2025

Abstract

Solar flares are the most powerful, magnetically driven, explosions in the heliosphere. The nature of magnetic energy release in the solar corona that heats the plasma and accelerates particles in a flare, however, remains poorly understood. Here, we report high-resolution coronal observations of a flare by the Solar Orbiter mission that reveal initially weaker but rapid reconnection events, on timescales of a few seconds at most, leading to a more prominent activity of a similar nature that explosively causes a flare. Signatures of this process are further imprinted on the widespread raining plasma blobs with short lifetimes, giving rise to the characteristic ribbon-like emission pattern associated with the flare. Our observations unveil the central engine of a flare and emphasize the crucial role of an avalanche-like magnetic energy release mechanism at work.