Thermodynamic evolution of a sigmoidal active region with associated flares
Thermodynamic evolution of a sigmoidal active region with associated flares
复制标题
DOI：
10.1093/mnras/stab816
复制
发表时间：
2021-03
影响因子：
4.8
通讯作者：
Sargam M. Mulay;D. Tripathi;H. Mason
中科院分区：
文献类型：
--
作者：
Sargam M. Mulay;D. Tripathi;H. Mason
日冕中的活跃区域通常呈现 S 形结构，称为 S 形结构。这些是沿着极性反转线形成的高度剪切和扭曲的环。它们被认为是日冕物质抛射的最佳喷发前特征之一。在这里，我们研究了 2015 年 12 月 24 日至 28 日期间观察到的盘上 s 形曲线的热力学演化。为此，我们对太阳动力学观测站 (SDO) 上的大气成像组件 (AIA) 和 Hinode 上的 X 射线望远镜 (XRT) 记录的观测结果采用了发射测量 (EM) 和滤波器比技术。 EM 分析显示沿 S 形曲线存在多热等离子体，并为所有观察到的耀斑提供了~10-12.5 MK 的峰值温度。 S 形结构显示分别来自 AIA 94 和 131 Å 通道中的 Fe xviii (93.93 Å) 和 Fe xxi (128.75 Å) 线的发射。我们的结果表明，热等离子体通常局限于非常热的线束中。发现从 EM 分析获得的温度与使用 XRT、AIA 和 GOES 过滤器比率方法获得的温度非常一致。这些结果为活性区核心的 S 形结构的热力学建模提供了重要的约束。此外，这项研究还对可用于太阳日冕结构温度估计的不同技术进行了基准测试。
Active regions often show S-shaped structures in the corona called sigmoids. These are highly sheared and twisted loops formed along the polarity inversion line. They are considered to be one of the best pre-eruption signatures for CMEs. Here, we investigate the thermodynamic evolution of an on-disc sigmoid observed during 2015 December 24–28. For this purpose, we have employed Emission Measure (EM) and filter-ratio techniques on the observations recorded by the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics Observatory (SDO) and X-ray Telescope (XRT) on-board Hinode. The EM analysis showed multithermal plasma along the sigmoid and provided a peak temperature of ∼10–12.5 MK for all observed flares. The sigmoidal structure showed emission from Fe xviii (93.93 Å) and Fe xxi (128.75 Å) lines in the AIA 94 and 131 Å channels, respectively. Our results show that the hot plasma is often confined to very hot strands. The temperature obtained from the EM analysis was found to be in good agreement with that obtained using the XRT, AIA, and GOES filter-ratio methods. These results provide important constraints for the thermodynamic modelling of sigmoidal structures in the core of active regions. Moreover, this study also benchmarks different techniques available for temperature estimation in solar coronal structures.