Collier, Hannah ; Krucker, Säm ; Hayes, Laura ; Kraaikamp, Emil ; Berghmans, David ; Ryan, Daniel

Talk presented at 10th Solar Orbiter Workshop on 2026-03-18

Abstract: By studying the dynamics of flare ribbons, one obtains an indirect measurement of reconnection in the corona. The aim of this work is to quantify the spatial and temporal scales of EUV flare ribbon kernels as a probe of the spatial extent and duration of energy injection in solar flares. To do this, unprecedented data from the March 2024 major flare campaign of Solar Orbiter were used. These data were obtained at high-cadence in short-exposure mode with the Extreme Ultraviolet Imager's HRI telescope. Individual kernels were automatically identified and from this, the size distributions of kernels for different intensity thresholds were derived. In addition, an average light curve of individual kernels was extracted. Our analysis shows that a significant fraction of kernels were unresolved at a plate scale of 135 km/pix. Furthermore, we derived incredibly short injection times of less than a few seconds. These results emphasise the small spatial and short temporal scales involved in flare energy release. These findings necessitate an in-depth investigation into the implications of such small areas and short injections on the energy flux deposited in solar flares, and the response of the atmosphere.

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