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arXiv 1111.4360astro-ph.SR
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SDO/AIA观测到的螺旋扭折不稳定性引起的CME的起始和伴随耀斑

Initiation of CME and Associated Flare Caused by Helical Kink Instability Observed by SDO/AIA

Pankaj Kumar, K. -S. Cho, S. -C. Bong, Sung-Hong Park, Y. H. Kim

摘要:

在本文中,我们提出了多波长观测的螺旋扭结不稳定性作为一个触发的CME发生在AR NOAA 11163 2011年2月24日。CME与M3.5肢体耀斑相关。SDO/AIA的高分辨率观测表明,爆发日珥中存在螺旋扭折不稳定性,这意味着磁场存在磁绳结构。增亮开始于日珥顶点以下,在激活阶段缓慢上升(约100 km/s)。在该位置瞬时形成明亮的结构,指示具有约3-4圈的螺旋。根据最近发展的模型,~ $6π-8π$的相应扭曲足以在磁绳中产生螺旋扭折不稳定性。随后在日珥的顶点形成了一个缓慢上升的团块结构,并在足点附近观察到一个耀斑环。在两分钟内,第二个斑点在日珥的北部形成。第二个团爆发(像一个等离子体喷射)与北部的突出腿的分离,耀斑强度最大化。在日珥顶点的第一个斑点显示出在天空平面上逆时针方向的旋转运动,被解释为螺旋的解旋运动,它也爆发出日冕物质抛射(CME)。RHESSI硬X射线源显示耀斑期间有两个足点源和一个环顶源。我们发现RHESSI硬X射线通量、软X射线通量导数和低日冕CME加速度有很好的相关性,这与标准耀斑模型(CSHKP)的结果一致。我们还讨论了气球以及环面不稳定性在推动日冕物质抛射中可能发挥的作用。我们的结论是,CME和耀斑是由磁绳中的螺旋扭折不稳定性触发的,主要是由环面不稳定性加速的。

英文摘要:

In this paper, we present multiwavelength observations of helical kink instability as a trigger of a CME which occurred in AR NOAA 11163 on 24 February 2011. The CME was associated with a M3.5 limb flare. High resolution observations from SDO/AIA suggest the development of helical kink instability in the erupting prominence, which implies a flux rope structure of the magnetic field. A brightening starts below the apex of the prominence with its slow rising motion (~100 km/s) during the activation phase. A bright structure, indicative of a helix with ~3-4 turns, was transiently formed at this position. The corresponding twist of ~$6π-8π$ is sufficient to generate the helical kink instability in a flux rope according to recently developed models. A slowly rising blob structure was subsequently formed at the apex of the prominence, and a flaring loop was observed near the footpoints. Within two minutes, a second blob was formed in the northern prominence leg. The second blob erupts (like a plasmoid ejection) with the detachment of the northern prominence leg, and flare intensity maximizes. The first blob at the prominence apex shows rotational motion in the counterclockwise direction in the plane of sky, interpreted as unwinding motion of a helix, and it also erupts to give the coronal mass ejection (CME). RHESSI hard X-ray sources show the two footpoint sources and a loop-top source during the flare. We found RHESSI hard X-ray flux, soft X-ray flux derivative and CME acceleration in the low corona correlate well, which is in agreement with the standard flare model (CSHKP). We also discuss the possible role of ballooning as well as torus instabilities in driving the CME. We conclude that the CME and flare were triggered by the helical kink instability in a flux rope and accelerated mainly by the torus instability.

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