Hot Plasma Flows and Oscillations in the Loop-top Region During the 2017 September 10 X8.2 Solar Flare
Hot Plasma Flows and Oscillations in the Loop-top Region During the 2017 September 10 X8.2 Solar Flare
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DOI：
10.3847/1538-4357/abc4e0
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发表时间：
2020-12-01
影响因子：
4.9
通讯作者：
Li, Gang
中科院分区：
文献类型：
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作者：
Reeves, Katharine K.;Polito, Vanessa;Li, Gang
在这项研究中，我们研究了2017年9月10日X8.2耀斑事件期间耀斑环上方热等离子体的运动。我们研究了主耀斑拱廊以南的区域，那里有来自日出的界面区成像光谱仪（IRIS）和极紫外成像光谱仪（EIS）的数据。我们发现，在IRIS的Fe xxi线和EIS的Fe xxiv线上，在这一区域观测到了20-60 km/s的初始蓝移，并且这些蓝移的位置沿拱廊向南沿着移动了大约10分钟。IRIS的节奏，使我们能够遵循这些流量的演变，我们发现，在每个位置，有一个初始的蓝移在Fe XXI线，有阻尼振荡的多普勒速度与周期类似的400秒。我们的结论是，这些周期是独立的环路长度，排除磁声驻模作为一种可能的机制。来自扩展欧文斯谷太阳能阵列（EOVSA）的微波观测表明，在观测到多普勒频移的区域存在非热辐射，这表明存在加速粒子。我们认为，流动和振荡是由于磁场的运动所造成的重联外流干扰的环顶区域。
In this study, we investigate motions in the hot plasma above the flare loops during the 2017 September 10 X8.2 flare event. We examine the region to the south of the main flare arcade, where there is data from the Interface Region Imaging Spectrograph (IRIS) and the Extreme ultraviolet Imaging Spectrometer (EIS) on Hinode. We find that there are initial blueshifts of 20-60 km s(-1) observed in this region in the Fe xxi line in IRIS and the Fe xxiv line in EIS, and that the locations of these blueshifts move southward along the arcade over the course of about 10 minutes. The cadence of IRIS allows us to follow the evolution of these flows, and we find that at each location where there is an initial blueshift in the Fe xxi line, there are damped oscillations in the Doppler velocity with periods of similar to 400 s. We conclude that these periods are independent of loop length, ruling out magnetoacoustic standing modes as a possible mechanism. Microwave observations from the Expanded Owens Valley Solar Array (EOVSA) indicate that there are nonthermal emissions in the region where the Doppler shifts are observed, indicating that accelerated particles are present. We suggest that the flows and oscillations are due to motions of the magnetic field that are caused by reconnection outflows disturbing the loop-top region.