Can Subphotospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona?
Can Subphotospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona?
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DOI：
10.3847/1538-4357/ab7dcb
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
D. Baker;L. Driel-Gesztelyi;D. Brooks;P. Démoulin;G. Valori;D. Long;J. Laming;A. To;A. James
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文献类型：
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作者：
D. Baker;L. Driel-Gesztelyi;D. Brooks;P. Démoulin;G. Valori;D. Long;J. Laming;A. To;A. James
在恒星的日冕中，低第一电离势（FIP）元素的丰度通常与它们的光球值不同。太阳和太阳型恒星的日冕大多表现出低FIP元素的增强（FIP效应），而更活跃的恒星，如M矮星的日冕通常具有逆FIP效应（I-FIP）。在AR 12673中，我们观察到了I-FIP效应太阳等离子体的斑块，这是一个高度复杂的βγδ活动区。我们认为，合并的太阳黑子的本影，更具体地说，在本影内的强光桥，是观察I-FIP效应等离子体的首选位置。此外，活动区的磁场复杂性和快速通量出现的主要事件也导致了重复和强烈的耀斑。在穿越本影的耀斑带中色球等离子体的诱导蒸发使得在AR 12673的日冕中观测到四个局部的I-FIP效应等离子体斑块。这些观测结果可以解释的有质动力分馏模型的上下文中预测，等离子体与I-FIP效应的组合物是由来自色球层以下的波的折射。我们认为，在太阳活动区产生I-FIP效应等离子体的波是由合并通量系统的次光球重联产生的。虽然我们只瞥见签名的I-FIP效应分馏产生的这种相互作用在太阳上的补丁，在高度活跃的M星，它可能是占主导地位的过程。
Within the coronae of stars, abundances of those elements with low first ionization potential (FIP) often differ from their photospheric values. The coronae of the Sun and solar-type stars mostly show enhancements of low-FIP elements (the FIP effect) while more active stars such as M dwarfs have coronae generally characterized by the inverse-FIP effect (I-FIP). Here we observe patches of I-FIP effect solar plasma in AR 12673, a highly complex βγδ active region. We argue that the umbrae of coalescing sunspots, and more specifically strong light bridges within the umbrae, are preferential locations for observing I-FIP effect plasma. Furthermore, the magnetic complexity of the active region and major episodes of fast flux emergence also lead to repetitive and intense flares. The induced evaporation of the chromospheric plasma in flare ribbons crossing umbrae enables the observation of four localized patches of I-FIP effect plasma in the corona of AR 12673. These observations can be interpreted in the context of the ponderomotive force fractionation model which predicts that plasma with I-FIP effect composition is created by the refraction of waves coming from below the chromosphere. We propose that the waves generating the I-FIP effect plasma in solar active regions are generated by subphotospheric reconnection of coalescing flux systems. Although we only glimpse signatures of I-FIP effect fractionation produced by this interaction in patches on the Sun, on highly active M stars it may be the dominant process.