Large-scale Magnetic Funnels in the Solar Corona
Large-scale Magnetic Funnels in the Solar Corona
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DOI：
10.3847/1538-4357/ab017c
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发表时间：
2016-05
期刊：
影响因子：
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通讯作者：
O. Panasenco;M. Velli;A. Panasenco
中科院分区：
文献类型：
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作者：
O. Panasenco;M. Velli;A. Panasenco
我们描述了开放的日冕磁场与特定的几何-大规模的日冕磁漏斗-被发现在日冕动力学中发挥重要作用。日冕磁漏斗可以归结为三个主要因素：(i)伪流光的存在，（ii）细丝通道的存在，以及（iii）伪流光附近活跃区域的存在。磁漏斗的几何形状在2r⊙以下表现出强烈的非单调膨胀。我们提出了一个漏斗的详细研究，从赤道附近的双重伪流线，形成在三个日冕洞之间的相同极性。通过跟踪这些日冕洞的演化，我们发现当两个日冕洞合并在一起时，伪流和漏斗拓扑结构发生了变化。合并后，开放磁场的漏斗几何形状变得平滑，具有单调的膨胀因子。磁漏斗的存在是由日冕中日冕云日珥的出现间接证实的，通常是在304 Å通带，这是由于周围大气爆发后较冷的等离子体碎片落回太阳的结果。日冕云出现悬浮在1.2-1.3 R⊙的高度，与磁场梯度最强的区域一致。通过研究几个太阳旋转过程中漏斗开放磁场的演变，我们发现在日冕高处日冕云的存在与其下方漏斗磁场的同时存在之间存在着直接的关系。
We describe open coronal magnetic fields with a specific geometry—large-scale coronal magnetic funnels—that are found to play an important role in coronal dynamics. Coronal magnetic funnels can be attributed to three main factors: (i) the presence of pseudostreamer(s), (ii) the presence of filament channels, and (iii) the presence of active regions in the close vicinity of a pseudostreamer. The geometry of magnetic funnels displays a strongly nonmonotonic expansion below 2 R⊙. We present a detailed study of a funnel arising from a double pseudostreamer near the equator, formed between a triplet of coronal holes of the same polarity. By following the evolution of these coronal holes we find that the pseudostreamer and, therefore, funnel topology, changes when two coronal holes have merged together. The funnel geometry of the open magnetic field becomes smoother, with a monotonic expansion factor, after this merging. The presence of magnetic funnels is indirectly confirmed by the appearance of coronal cloud prominences in the solar corona, typically in the 304 Å passband, as a result of colder plasma debris falling back toward the Sun in the wake of eruptions in the surrounding atmosphere. The coronal clouds appear suspended at heights of 1.2–1.3 R⊙, coinciding with the region of strongest gradients in the magnetic field. By studying the evolution of funnel open magnetic fields over several solar rotations we find a direct relation between the presence of coronal clouds high in the solar corona and the coincident existence of funnel magnetic fields below them.