On 2024 May 10–11, the strongest geomagnetic storm since 2003 November occurred, with a peak Dst index of −412 nT. The storm was caused by NOAA active region (AR) 13664, which was the source of a large number of coronal mass ejections and flares, including 12 X-class flares. Starting from about May 7, AR 13664 showed a steep increase in its size and (free) magnetic energy, along with increased flare activity. In this study, we perform 3D magnetic field extrapolations with the NF2 nonlinear force-free code based on physics-informed neural networks (R. Jarolim et al.). In addition, we introduce the computation of the vector potential to achieve divergence-free solutions. We extrapolate vector magnetograms from the Solar Dynamics Observatory’s Helioseismic and Magnetic Imager at the full 12 minute cadence from 2024 May 5 00:00 to 11 04:36 UT, in order to understand the AR’s magnetic evolution and the large eruptions it produced. A decrease in the calculated relative free magnetic energy can be related to solar flares in ∼90% of the cases, and all considered X-class flares are reflected by a decrease in the relative free magnetic energy. Regions of enhanced free magnetic energy and depleted magnetic energy between the start and end times of major X-class flares show spatial alignment with brightness increases in extreme-ultraviolet observations. We provide a detailed analysis of the X3.9-class flare on May 10, where we show that the interaction between separated magnetic domains is directly linked to major flaring events. With this study, we provide a comprehensive data set of the magnetic evolution of AR 13664 and make it publicly available for further analysis.

中文翻译：

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太阳活动区磁场演化 13664


2024 年 5 月 10 日至 11 日，发生了自 2003 年 11 月以来最强的地磁暴，峰值 Dst 指数为 -412 nT。这场风暴是由 NOAA 活动区 （AR） 13664 引起的，该区域是大量日冕物质抛射和耀斑的来源，包括 12 次 X 级耀斑。从大约5月7日开始，AR 13664的大小和（自由）磁能急剧增加，耀斑活动也增加了。在这项研究中，我们使用基于物理信息神经网络的 NF2 非线性无力代码（R. Jarolim 等人）进行 3D 磁场外推。此外，我们还介绍了矢量势的计算，以实现无发散的解。我们从太阳动力学天文台的日震和磁成像仪中推断出矢量磁图，从 2024 年 5 月 5 日 00：00 到 11 日 04：36 UTC，以整整 12 分钟的节奏推断出矢量磁图，以了解 AR 的磁演变及其产生的大型喷发。在 ∼90% 的情况下，计算出的相对自由磁能的减少可能与太阳耀斑有关，并且所有考虑的 X 级耀斑都反映在相对自由磁能的减少上。在主要 X 级耀斑的开始和结束时间之间，自由磁能增强和磁能耗尽的区域在极端紫外观测中显示出与亮度增加的空间对齐。我们对 5 月 10 日的 X3.9 级耀斑进行了详细分析，其中我们表明分离的磁畴之间的相互作用与主要耀斑事件直接相关。通过这项研究，我们提供了 AR 13664 磁演化的全面数据集，并将其公开以供进一步分析。