The Merging of a Coronal Dimming and the Southern Polar Coronal Hole
The Merging of a Coronal Dimming and the Southern Polar Coronal Hole
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DOI：
10.3847/1538-4357/acd44e
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发表时间：
2023-05
期刊：
影响因子：
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通讯作者：
Nawin Ngampoopun;D. Long;D. Baker;L. Green;S. Yardley;A. James;A. To
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作者：
Nawin Ngampoopun;D. Long;D. Baker;L. Green;S. Yardley;A. James;A. To
我们报告了2022年3月18日由日冕物质抛射引起的南极日冕洞和相邻日冕变暗之间的合并，导致合并区域持续至少72小时。我们使用来自多个共同观测航天器的遥感数据来了解这次合并事件的物理过程。合并的演变是用太阳动力天文台和太阳轨道飞行器上的极紫外成像仪上的大气成像组件获得的极紫外（EUV）图像来检查的。利用日野号上的EUV成像光谱仪获得的光谱数据对等离子体动力学进行了量化。利用日震和磁成像仪的光球磁图推导了磁场性质。据我们所知，这项工作是首次对两个开放场结构合并进行光谱分析。我们发现，合并后的日冕空洞和日冕变暗变得难以区分。日冕变暗内部的上升流速度与日冕洞的上升流速度更加相似，在合并后可以观察到等离子体的上升流和下降流。亮点的变亮和合并区域内日冕喷流的出现进一步暗示了正在进行的重连过程。我们认为，日冕洞和日冕调暗场之间的分量重连在这一合并事件中起着重要作用，因为由重连引起的足点切换使日冕调暗侵入到南极日冕洞的边界上。
We report on the merging between the southern polar coronal hole and an adjacent coronal dimming induced by a coronal mass ejection on 2022 March 18, resulting in the merged region persisting for at least 72 hr. We use remote sensing data from multiple co-observing spacecraft to understand the physical processes during this merging event. The evolution of the merger is examined using Extreme-UltraViolet (EUV) images obtained from the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory and Extreme Ultraviolet Imager, which is on board the Solar Orbiter spacecraft. The plasma dynamics are quantified using spectroscopic data obtained from the EUV Imaging Spectrometer on board Hinode. The photospheric magnetograms from the Helioseismic and Magnetic Imager are used to derive the magnetic field properties. To our knowledge, this work is the first spectroscopical analysis of the merging of two open-field structures. We find that the coronal hole and the coronal dimming become indistinguishable after the merging. The upflow speeds inside the coronal dimming become more similar to that of a coronal hole, with a mixture of plasma upflows and downflows observable after the merging. The brightening of the bright points and the appearance of coronal jets inside the merged region further imply ongoing reconnection processes. We propose that component reconnection between the coronal hole and coronal dimming fields plays an important role during this merging event because the footpoint switching resulting from the reconnection allows the coronal dimming to intrude onto the boundary of the southern polar coronal hole.