HEATING MECHANISMS FOR INTERMITTENT LOOPS IN ACTIVE REGION CORES FROM AIA/ SDO EUV OBSERVATIONS
HEATING MECHANISMS FOR INTERMITTENT LOOPS IN ACTIVE REGION CORES FROM AIA/ SDO EUV OBSERVATIONS
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来自 AIA/SDO EUV 观测的活动区域核心间歇循环的加热机制
DOI：
10.1088/0004-637x/795/1/48
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Cadavid A
中科院分区：
文献类型：
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作者：
Cadavid A
我们研究了活动区核心的五个日冕环中的强度变化和能量沉积。选择它们是因为它们在 AIA/SDO 94 Å 强度通道中具有很强的可变性。我们通过建模并减去对发射的“热”贡献，分离出 94 Å 和 131 Å 的热 Fe xviii 和 Fe xxi 成分。 HMI/SDO 数据使我们能够专注于循环中的“苔藓间”区域。苔藓间强度时间序列的详细演变揭示了以与纳米耀斑风暴兼容的模式脉冲加热的循环，其中热 131 Å 信号中的尖峰领先，其他五个 EUV 发射通道按照渐进冷却顺序跟随。在 131 Å 热信号之后，电子温度往往会急剧上升，这证实了该过程的脉冲性质。排放量增长的较冷过程随之而来的速度较慢。当对五个环路进行平均时，热 131 Å 信号的傅里叶功率谱呈现出三种标度范围，其拐点频率接近 0.1 min− 1 和 0.7 min− 1。低频范围对应于 1/f 噪声；低频范围对应于 1/f 噪声；低频范围对应于 1/f 噪声。中间表示持续的缩放过程，高频显示白噪声。基于简化的磁流体动力学，在环形磁湍流的二维“混合”壳模型中发现了非常相似的能量耗散结果，该模型与纳米耀斑统计数据兼容。我们认为这种湍流耗散是我们循环的能量来源。
We investigate intensity variations and energy deposition in five coronal loops in active region cores. These were selected for their strong variability in the AIA/SDO 94 Å intensity channel. We isolate the hot Fe xviii and Fe xxi components of the 94 Å and 131 Å by modeling and subtracting the" warm" contributions to the emission. HMI/SDO data allow us to focus on" inter-moss" regions in the loops. The detailed evolution of the inter-moss intensity time series reveals loops that are impulsively heated in a mode compatible with a nanoflare storm, with a spike in the hot 131 Å signals leading and the other five EUV emission channels following in progressive cooling order. A sharp increase in electron temperature tends to follow closely after the hot 131 Å signal confirming the impulsive nature of the process. A cooler process of growing emission measure follows more slowly. The Fourier power spectra of the hot 131 Å signals, when averaged over the five loops, present three scaling regimes with break frequencies near 0.1 min− 1 and 0.7 min− 1. The low frequency regime corresponds to 1/f noise; the intermediate indicates a persistent scaling process and the high frequencies show white noise. Very similar results are found for the energy dissipation in a 2D" hybrid" shell model of loop magneto-turbulence, based on reduced magnetohydrodynamics, that is compatible with nanoflare statistics. We suggest that such turbulent dissipation is the energy source for our loops.