Three-dimensional Analysis of a C-class Flare Observed with Sunrise III/SCIP

Abstract Deciphering the physical properties of flares is crucial for understanding the nature of one of the most energetic events on the Sun. We analyze high spatial and spectral resolution observations of a C-class flare, focusing on a complex light bridge in the active region. The observations show Stokes profiles with opposite Doppler shifts and asymmetries between photospheric and chromospheric spectral lines, and Ca ii infrared spectral lines in emission, tracing areas of extreme atmospheric heating. Inversion results are consistent with these spectral features, showing regions of opposite-sign plasma flows between the photosphere and chromosphere, adjacent to areas with extreme chromospheric temperatures. The latter areas show relatively weak line-of-sight velocities despite the intense heating. The magnetic field configuration shows abrupt changes with height in the regions with opposite-sign flows, while remaining nearly constant with height in the areas of extreme heating. These findings point to a scenario of small-scale magnetic reconnection in the photosphere, suggesting a flare triggering mechanism based on an avalanche of many small reconnection events.