Characterizing 3D Magnetic Structures in Sunspot Light Bridges
Characterizing 3D Magnetic Structures in Sunspot Light Bridges
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DOI：
10.3847/1538-4357/acd44f
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发表时间：
2023-07
期刊：
影响因子：
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通讯作者：
J. Jing;Nian Liu;Jeongwoo Lee;Yan Xu;W. Cao;Haimin Wang
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作者：
J. Jing;Nian Liu;Jeongwoo Lee;Yan Xu;W. Cao;Haimin Wang
光桥（LB）是划分太阳黑子本影的狭窄结构，其在活动区域演化中的作用仍有待探索。我们研究了NOAA 12371活动区中两个LB的磁结构：一个窄LB（宽度约810 km）和一个相当宽的LB（2475 km）。我们采用：（1）由1.6 m古德太阳望远镜（GST）的近红外成像分光计（NIRIS）获得的高空间分辨率分光偏振数据进行研究 光球层的磁结构，以及（2）非线性无力场（NLFFF）模型，从 GST/NIRIS 的光球磁图和太阳动力学天文台上的日震和磁成像仪推断出来，用于在更大范围内研究三维（3D）磁结构。我们的观察揭示了两个LB内部存在无场（或更准确地说，弱场）区域和不同的速度结构。对 3D NLFFF 模型的分析显示了低洼磁冠以及 LB 上方的增强电流系统。 LB 和本影之间的显着差异在于整体磁拓扑中，因为从两个 LB 发出的磁力线比邻近本影发出的磁力线更加扭曲。
Light bridges (LBs) are narrow structures dividing sunspot umbra, and their role in active region evolution is yet to be explored. We investigated the magnetic structure of the two LBs: a narrow LB (with width ∼810 km) and a considerably wider LB (2475 km) in the active region NOAA 12371. We employed: (1) the high-spatial-resolution spectropolarimetric data obtained by the Near InfraRed Imaging Spectropolarimeter (NIRIS) of the 1.6 m Goode Solar Telescope (GST) for studying the magnetic structure at the photosphere, and (2) the nonlinear force-free field (NLFFF) models, extrapolated from both the photospheric magnetogram from GST/NIRIS and from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, for studying the three-dimensional (3D) magnetic structure on a larger scale. Our observations reveal the presence of a field-free (or, more precisely, weak-field) region and the different velocity structures inside the two LBs. Analysis of the 3D NLFFF model shows a low-lying magnetic canopy as well as the enhanced current system above the LBs. The substantial difference between the LBs and the umbrae is found in the overall magnetic topology in that the field lines emanating from the two LBs are more twisted than that from the neighboring umbrae.