Research on the Mechanism of Sequential Flares

Abstract Coronal mass ejections exert significant influences on the space environment of Earth, which warrants particular attention. An important question in solar physics is why some large solar flares erupt successfully while others remain confined. In this study, we analyzed two consecutive flares: a confined M7.5 flare and an eruptive X1.3 flare in NOAA active region 13663 on 2024 May 5. The first flare was triggered at the initial polarity inversion line (PIL) and subsequently expanded toward the main PIL. The second flare occurred at the main PIL. In order to understand their underlying mechanism, we reconstruct their coronal magnetic configuration. Based on magnetic topology, we summarize an eruption scenario. The first flare was triggered by tether-cutting reconnection and propagated to the main PIL through the overlying magnetic arcade, inducing changes in the magnetic structure. The second flare was triggered by hyperbolic flux tube reconnection resulting from these variations. According to this scenario, we confirm that the first flare dissipated the overlying field above the region of the second flare, created the magnetic flux rope (MFR), and strengthened the core field of the MFR through tether-cutting reconnection and intermittent reconnection. This study helps us better understand how the previous confined flare contributes to the subsequent eruptive flare and how magnetic field reconstruction caused by confined flares can lead to more intense eruptions.