2025/12/01 by Denker, Carsten, Kamlah, Robert, Verma, Meetu +1
Physics and Astronomy · #FOS: Physical sciences #Ionosphere and magnetosphere dynamics #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies
paper · doi:10.48550/arxiv.2512.01642
openalex publication_date 2025/12/01 · openalex created_date 2025/12/03 · openalex updated_date 2026/07/28
Active region NOAA 14274 produced some of the strongest flares of Solar Cycle 25, including the X1.2 and X5.1 flares on 10 and 11 November 2025, respectively. We present the first large mosaic of speckle-restored images obtained with the improved High-resolution Fast Imager (HiFI+) at the 1.5-meter GREGOR solar telescope at the Observatorio del Teide in Izaña, Tenerife, Spain. The observations were obtained approximately 30 minutes before the onset of the X1.2 flare. The active region exhibited strongly curved penumbral filaments, sunspot rotation, and shear motions along the polarity inversion line (PIL), which led to a highly stressed magnetic field configuration that stored sufficient energy to release multiple M- and X-class flares. The first flare signatures appeared as small-scale brightenings, each with a width of a few tenths of an arcsecond, that trace penumbral filaments in the trailing sunspot.