| Presentation Title: | Genesis of a Confined X6.4 Flare in a Quadrupolar Magnetic Configuration |
| Author(s): | Chunming Zhu, C. Richard DeVore, Joel T. Dahlin, Jiong Qiu, Maria D. Kazachenko, Vadim M. Uritsky |
Abstract:
Both eruptive and confined flares – those having and lacking, respectively, an associated large-scale coronal mass ejection – are frequently observed in solar active regions (ARs). The physical mechanisms controlling the nature of these AR flares are poorly understood, and detailed investigation of both the magnetic environment and the dynamic flare production process within the source region is required. Here we study a confined X6.4 flare with a failed filament eruption in AR 13590 on 2024 February 22 that was observed by the SDO and HINODE spacecraft. AR 13590 had a quadrupolar magnetic configuration consisting of one central and two side arcades of low-lying loops, overlain by a fourth arcade of high-lying loops. A potential-field extrapolation contains a low-altitude null point at a height of about 5 Mm. This is a classic magnetic-breakout topology of the field, except that the rising filament lay under one of the side arcades. The confined flare generated four ribbons located in all four of the major polarities, and it proceeded in two steps. First, breakout reconnection in the null region between the fluxes in the two side arcades removed strapping field above the rising filament and initiated the formation of all four ribbons. Second, “anti-breakout” reconnection occurred at the null region between the high-lying arcade and the low-lying central arcade as those flux systems relaxed downward and upward, respectively, following the filament disruption. The two steps of breakout and “anti-breakout” reconnection are indicated by two successive stages of ribbon brightenings accompanied by forward, then reverse, motion of the brightenings along the interior ribbons. We discuss the physical mechanisms producing such strong confined flares while preventing much material from escaping from the Sun.