The Solar Minimum Eclipse of 2019 July 2. II. The First Absolute Brightness Measurements and MHD Model Predictions of Fe x, xi, and xiv out to 3.4 R ⊙
The Solar Minimum Eclipse of 2019 July 2. II. The First Absolute Brightness Measurements and MHD Model Predictions of Fe x, xi, and xiv out to 3.4 R ⊙
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DOI：
10.3847/1538-4357/ac8101
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发表时间：
2022-08-01
影响因子：
4.9
通讯作者：
Druckmuller, Miloslav
中科院分区：
文献类型：
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作者：
Boe, Benjamin;Habbal, Shadia;Druckmuller, Miloslav
我们给出了2019年7月2日日全食(TSE)期间观测到的1.08到3.4R(圆点)的Fex、Fexi和FeXIV可见日冕发射线的空间分辨绝对亮度。日冕的形态是典型的太阳活动极小值，其偶极场优势表现为大的极地冕洞和宽阔的赤道流光带。发现Fe-xi谱线最亮，其次是Fe-x和Fe-XIV(以圆点为单位)。所有谱线在流光和冕洞之间都有亮度变化，其中Fe XIV的变化最大。然而，Fex在纬度上保持着令人惊讶的一致。铁线亮度被用来推断整个日冕的相对离子丰度和视线平均电子温度(T(E))，在日冕空穴中得到1.25到1.4mK的值，在流光核心得到高达1.65mK的值。然后将线亮度和推断的T(E)值与Predictive Science Inc.对该TSE的磁流体模型预测进行定量比较。MHD模型总体上很好地预测了Fe谱线，而正演模型的谱线比率略微低估了观测推断的T(E)，整个日冕的平均T(E)在5%-10%之间。极地冕洞的较大差异可能指向加热不足和/或该方法中的其他限制。这些比较突出了TSE观测对于约束日冕和太阳风形成模型的重要性。
We present the spatially resolved absolute brightness of the Fe x, Fe xi, and Fe xiv visible coronal emission lines from 1.08 to 3.4 R (circle dot), observed during the 2019 July 2 total solar eclipse (TSE). The morphology of the corona was typical of solar minimum, with a dipole field dominance showcased by large polar coronal holes and a broad equatorial streamer belt. The Fe xi line is found to be the brightest, followed by Fe x and Fe xiv (in disk B (circle dot) units). All lines had brightness variations between streamers and coronal holes, where Fe xiv exhibited the largest variation. However, Fe x remained surprisingly uniform with latitude. The Fe line brightnesses are used to infer the relative ionic abundances and line-of-sight-averaged electron temperature (T ( e )) throughout the corona, yielding values from 1.25 to 1.4 MK in coronal holes and up to 1.65 MK in the core of streamers. The line brightnesses and inferred T ( e ) values are then quantitatively compared to the Predictive Science Inc. magnetohydrodynamic model prediction for this TSE. The MHD model predicted the Fe lines rather well in general, while the forward-modeled line ratios slightly underestimated the observationally inferred T ( e ) within 5%-10% averaged over the entire corona. Larger discrepancies in the polar coronal holes may point to insufficient heating and/or other limitations in the approach. These comparisons highlight the importance of TSE observations for constraining models of the corona and solar wind formation.