Coronal Magnetic Field Extrapolation and Topological Analysis of Fine-scale Structures during Solar Flare Precursors
Coronal Magnetic Field Extrapolation and Topological Analysis of Fine-scale Structures during Solar Flare Precursors
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DOI：
10.3847/1538-4357/ad0236
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发表时间：
2023-06
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影响因子：
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通讯作者：
W. He;J. Jing;Haimin Wang;S. Nayak;A. Prasad
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作者：
W. He;J. Jing;Haimin Wang;S. Nayak;A. Prasad
磁场在各种太阳喷发现象中起着重要作用。太阳喷发特征磁场拓扑的形成和演化是最终帮助我们理解太阳源区喷发起源的关键问题。随着先进技术和仪器的发展，在不同波长和视场下进行更高分辨率的观测为精细结构提供了更多的定量信息。因此，有必要改进利用高分辨率观测研究太阳源区磁场拓扑的方法。在这项研究中，我们使用了一种基于非均匀网格设置的非线性无力场外推方法，用于一次M级耀斑喷发事件(SOL2015-06-22T17：39)，其中嵌入了来自太阳动力学天文台(SDO)和古德太阳望远镜(GST)的矢量磁图。通过保持相应的GST和SDO磁图的固有分辨率，得到了采用非均匀嵌入底界磁图的外推结果。我们将场线连通性与同步观测的GST/Hα和SDO/大气成像组合观测结果进行了比较，这些细尺度结构与前兆亮化有关。然后根据外推结果对对应于细尺度磁场结构的场线连通性进行了拓扑分析。分析结果表明，当我们将高分辨率的GST磁图与SDO的较大磁图相结合时，所得到的磁场拓扑与太阳耀斑前兆期间横跨主极性反转线的切变场线之间的磁重联的情况是一致的。
Magnetic field plays an important role in various solar eruption phenomena. The formation and evolution of the characteristic magnetic field topology in solar eruptions are critical problems that will ultimately help us understand the origin of these eruptions in the solar source regions. With the development of advanced techniques and instruments, observations with higher resolutions in different wavelengths and fields of view have provided more quantitative information for finer structures. It is therefore essential to improve the method with which we study the magnetic field topology in the solar source regions by taking advantage of high-resolution observations. In this study, we employ a nonlinear force-free field extrapolation method based on a nonuniform grid setting for an M-class flare eruption event (SOL2015-06-22T17:39) with embedded vector magnetograms from the Solar Dynamics Observatory (SDO) and the Goode Solar Telescope (GST). The extrapolation results for which the nonuniform embedded magnetogram for the bottom boundary was employed are obtained by maintaining the native resolutions of the corresponding GST and SDO magnetograms. We compare the field line connectivity with the simultaneous GST/Hα and SDO/Atmospheric Imaging Assembly observations for these fine-scale structures, which are associated with precursor brightenings. Then we perform a topological analysis of the field line connectivity corresponding to fine-scale magnetic field structures based on the extrapolation results. The analysis results indicate that when we combine the high-resolution GST magnetogram with a larger magnetogram from the SDO, the derived magnetic field topology is consistent with a scenario of magnetic reconnection among sheared field lines across the main polarity inversion line during solar flare precursors.