Enhanced Peak and Extended Cooling of the Extreme-ultraviolet Late Phase in a Confined Solar Flare

• DOI: 10.3847/1538-4357/ad8ba3
• Publication Date: 2024-12-18T09:53:06Z
• Authors: Shihan Li; Yu Dai; Mingde Ding; Zhen Li; Jinhan Guo; Hao Wu
• Keywords: Solar flare; Ultraviolet; Extreme ultraviolet; Flare

Abstract We present observations and analysis of an X1.8 noneruptive solar flare on 2012 October 23, which is characterized by extremely large late-phase peak seen in the warm coronal extreme-ultraviolet (EUV) emissions (∼3 MK), with intensity over 1.4 times that main peak. The driven a failed eruption magnetic flux rope, whose strong squeeze force acting overlying structures gives rise to intense early heating loops. Based differential emission measure analysis, it found loops experience “longer-than-expected” cooling, without presence any obvious additional heating, while their volume maintains plateau for long time before turning into evident decay. Without need we propose special thermodynamic evolution revealed this might arise from loop cross-sectional expansions height, are evidenced both direct measurements EUV images field extrapolation. By blocking losses heat mass corona, such upward expansion not only elongates loop-cooling time, but also more effectively sustains density, therefore leading later-than-expected occurrence late phase combination sufficiently high further verify scenario analytically solving cooling process variable cross section.