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arXiv 2201.07389astro-ph.SR
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磁通量绳非径向喷发引起的横向冠环振荡

Transverse Coronal-Loop Oscillations Induced by the Non-radial Eruption of a Magnetic Flux Rope

Q. M. Zhang, J. L. Chen, S. T. Li, L. Lu, D. Li

摘要:

我们调查了2012年12月7日爆发的一个携带磁通量的磁绳引起的横向日冕环振荡。SDO/AIA在极紫外波段和BBSO地基望远镜在H $α$谱线中心观测了源自NOAA活动区(AR)11621的磁绳。磁绳的早期演化分为两个阶段:速度为$\approx$ 230\,km\,s $^{-1}$的缓慢上升阶段和速度为$\approx$ 706\,km\,s $^{-1}$的快速上升阶段。爆发产生C5.8耀斑,并且快速上升的开始与耀斑的HXR峰值时间一致。包埋日珥的速度较低,为$\approx$ 452\,km\,s $^{-1}$。在早期爆发的磁绳,附近的日冕环的干扰,并在水平和垂直方向上经历独立的扭结模式振荡。水平方向上的振荡具有$\approx$ 3.1 μ m的初始振幅、$\approx$ 294 μ s的周期和$\approx$ 645 μ s的阻尼时间。它在171年最引人注目,持续三到四个周期。垂直方向的振荡主要出现在171、193和211 μ m。初始振幅在3.4\,--\,5.2 μ m之间,平均振幅为4.5 μ m,周期在407 ~ 441 μ s之间,平均为423 μ s。振荡是阻尼的,并持续近四个周期。阻尼时间在570\,--\,1012秒之间,平均值为741秒。假设垂直振荡环为半圆形,我们根据它们的高度计算环的长度。利用观测到的周期,我们进行了冠状地震学,并估计了振荡环的内部阿尔文速度(988,--\,1145\,km\,s $^{-1}$)和磁场强度(12,--\,43\,G)。

英文摘要:

We investigate the transverse coronal-loop oscillations induced by the eruption of a prominence-carrying flux rope on 7 December 2012. The flux rope originating from NOAA Active Region (AR) 11621 was observed in EUV wavelengths by the SDO/AIA and in H$α$ line center by the ground-based telescope at the BBSO. The early evolution of the flux rope is divided into two steps: a slow rise phase at a speed of $\approx$230\,km\,s$^{-1}$ and a fast rise phase at a speed of $\approx$706\,km\,s$^{-1}$. The eruption generates a C5.8 flare and the onset of the fast rise is consistent with the HXR peak time of the flare. The embedded prominence has a lower speed of $\approx$452\,km\,s$^{-1}$. During the early eruption of the flux rope, the nearby coronal loops are disturbed and experience independent kink-mode oscillations in the horizontal and vertical directions. The oscillation in the horizontal direction has an initial amplitude of $\approx$3.1\,Mm, a period of $\approx$294\,seconds, and a damping time of $\approx$645\,seconds. It is most striking in 171\,Å and lasts for three to four cycles. The oscillations in the vertical directions are observed mainly in 171, 193, and 211\,Å. The initial amplitudes lie in the range of 3.4\,--\,5.2\,Mm, with an average value of 4.5\,Mm. The periods are between 407\,seconds and 441\,seconds, with an average value of 423\,seconds. The oscillations are damping and last for nearly four cycles. The damping times lie in the range of 570\,--\,1012\,seconds, with an average value of 741\,seconds. Assuming a semi-circular shape of the vertically oscillating loops, we calculate the loop lengths according to their heights. Using the observed periods, we carry out coronal seismology and estimate the internal Alfvén speeds (988\,--\,1145\,km\,s$^{-1}$) and the magnetic-field strengths (12\,--\,43\,G) of the oscillating loops.

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