DETERMINING THE STRUCTURE OF SOLAR CORONAL LOOPS USING THEIR EVOLUTION
DETERMINING THE STRUCTURE OF SOLAR CORONAL LOOPS USING THEIR EVOLUTION
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DOI：
10.1088/0004-637x/733/1/59
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发表时间：
2011-05
期刊：
影响因子：
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通讯作者：
Fana M. Mulu-Moore;A. Winebarger;H. Warren;M. Aschwanden
中科院分区：
文献类型：
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作者：
Fana M. Mulu-Moore;A. Winebarger;H. Warren;M. Aschwanden
尽管在了解日冕的动力学方面取得了重大进展，但关于日冕环的基本物理性质仍然存在一些未解之谜。最近从不同的仪器观测到了一些相互矛盾的结果，日冕环的一些特点，特别是对于所观察到的环是否空间分辨。在本文中，我们通过两个极端紫外线过滤器研究日冕环的演变，并确定它们是否演变为一个单一的冷却链。我们测量的时间演化的八个活跃的区域循环以前研究，发现是等温的，并解决了Aschwanden和南丁格尔。所有八个环都出现在“较热”的TRACE滤波器图像（Fe xii 195 μ m）中，然后出现在“较冷”的（Fe ix/Fe x 171 μ m）TRACE滤波器图像中。我们使用两个滤波器之间的测量延迟来计算冷却时间，然后确定冷却时间是否与观察到的环路寿命一致。我们这样做两次：一次是在循环出现时（上升阶段），一次是在循环消失时（衰减阶段）。我们发现，只有一个循环似乎与一个单一的冷却链一致，因此可以被认为是解决了跟踪。对于剩余的七个回路，它们的观察寿命比单个冷却链的预期寿命长。我们认为，这些环路可以形成多个冷却股，每个在不同的温度。这些发现表明，大多数环观察到的TRACE是未解决的。
Despite significant progress in understanding the dynamics of the corona, there remain several unanswered questions about the basic physical properties of coronal loops. Recent observations from different instruments have yielded contradictory results about some characteristics of coronal loops, specifically as to whether the observed loops are spatially resolved. In this paper, we examine the evolution of coronal loops through two extreme-ultraviolet filters and determine if they evolve as a single cooling strand. We measure the temporal evolution of eight active region loops previously studied and found to be isothermal and resolved by Aschwanden & Nightingale. All eight loops appear in “hotter” TRACE filter images (Fe xii 195 Å) before appearing in the “cooler” (Fe ix/Fe x 171 Å) TRACE filter images. We use the measured delay between the two filters to calculate a cooling time and then determine if that cooling time is consistent with the observed lifetime of the loop. We do this twice: once when the loop appears (rise phase) and once when it disappears (decay phase). We find that only one loop appears consistent with a single cooling strand and hence could be considered to be resolved by TRACE. For the remaining seven loops, their observed lifetimes are longer than expected for a single cooling strand. We suggest that these loops could be formed of multiple cooling strands, each at a different temperature. These findings indicate that the majority of loops observed by TRACE are unresolved.