We study a complex GOES M1.1 circular ribbon flare and related pre-flare activity on 26 January 2015 [SOL2015-01-26T16:53] in the solar active region NOAA 12268. This flare activity was observed by the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The examination of photospheric magnetograms during the extended period, prior to the event, suggests the successive development of a so-called “anemone” type magnetic configuration. The Nonlinear Force Free Field (NLFFF) extrapolation reveals a fan-spine magnetic configuration with the presence of a coronal null-point. We found that the pre-flare activity in the active region starts ≈15 min prior to the main flare in the form of localized bright patches at two locations. A comparison of locations and spatial structures of the pre-flare activity with magnetic configuration of the corresponding region suggests onset of magnetic reconnection at the null-point along with the low-atmosphere magnetic reconnection caused by the emergence and the cancellation of the magnetic flux. The main flare of M1.1 class is characterized by the formation of a well-developed circular ribbon along with a region of remote brightening. Remarkably, a set of relatively compact parallel ribbons formed inside the periphery of the circular ribbon which developed lateral to the brightest part of the circular ribbon. During the peak phase of the flare, a coronal jet is observed at the north-east edge of the circular ribbon, which suggests interchange reconnection between large-scale field lines and low-lying closed field lines. Our investigation suggests a combination of two distinct processes in which ongoing pre-flare null-point reconnection gets further intensified as the confined eruption along with jet activity proceeded from within the circular ribbon region which results to the formation of inner parallel ribbons and corresponding post-reconnection arcade.

中文翻译：

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受限圆形-暨-平行带状耀斑和相关的耀斑前活动的发展

我们研究了 2015 年 1 月 26 日 [SOL2015-01-26T16:53] 在太阳活动区 NOAA 12268 中复杂的 GOES M1.1 圆形带状耀斑和相关的耀斑前活动。大气成像组件 (AIA) 观测到了这种耀斑活动) 上的太阳动力学天文台 (SDO) 和鲁文拉马蒂高能太阳光谱成像仪 (RHESSI)。在事件发生之前的延长时期内对光球磁图的检查表明，所谓的“海葵”型磁性结构的连续发展。非线性自由力场 (NLFFF) 外推法揭示了扇形脊柱磁构型，并存在日冕零点。我们发现活动区域的预耀斑活动在主要耀斑之前约 15 分钟以两个位置的局部亮斑的形式开始。将耀斑前活动的位置和空间结构与相应区域的磁构型进行比较，表明在零点开始磁重联以及由磁通量的出现和抵消引起的低大气磁重联。M1.1级的主耀斑的特点是形成了一个发育良好的圆形带，并伴有一个远程增亮区域。值得注意的是，在圆形带的外围内部形成了一组相对紧凑的平行带，该带向圆形带的最亮部分横向发展。在耀斑的峰值阶段，在圆形带的东北边缘观察到日冕喷流，这表明大尺度场线和低洼封闭场线之间的交换重联。