2个太阳爆发事件中磁准分界面的演化

摘要

Quasi-separatrix layer,also called QSL,is a region where magnetic connectivity changes drastically and mostly well coincides with the location of flare ribbons in observations.The research on the relation between this topological structure and 3-dimensional magnetic reconnection,and solar flares has attracted more and more attention.In this paper,using the theory of QSL we investigate a C5.7 classical tworibbon solar flare (event 1) which occurred at ARl1384 on 2011 December 26 and an M6.5 solar flare (event 2) which occurred at AR12371 on 2015 June 22,respectively.Combining the multi-wavelength data of AIA (Atmospheric Imaging Assembly) and vector magnetogrames of HMI (Helioseismic and Magnetic Imager) onboard SDO (Solar Dynamics Observatory),we extrapolate the coronal magnetic field using the PF (Potential Field) model and NLFFF (Nonlinear Force Free Field) model,and calculate the evolution of the AR (Active Region) magnetic free energy first.Next,we calculate the slgQ maps of Q factor (magnetic squashing factor) at different heights away from solar photosphere with the extrapolation results of PF and NLFFF in order to decide the location of QSL.Then,we investigate the evolution relation between QSL at different heights away from solar photosphere and flaring brightening at the same layers.Finally,we study the multi-wavelength evolution features of the 2 flares.And,we calculate the observational slipping running speeds of event 2 in 304 (A) and 335 (A),which are 4.6 km·s-1 and 6.3 km.s-1,respectively.We find that the location of QSL calculated in chromosphere and corona is in good agreement with the location of flare ribbons at the same height,and the QSL at different layers has almost the same evolutionary behavior in time with the flaring brightening of the corresponding layer,which highlights the role of QSL in the research of 3D magnetic reconnection and solar flare,and we suggest that the flare may be triggered by the QSL reconnection.We also suggest that QSL is very important for us to research the essential connection between 3D magnetic reconnection and 2D magnetic reconnection.%磁准分界面(Quasi-Separatrix Layer,简称QSL)是3维磁结构中磁力线连接性发生显著改变的区域,观测表明它多数时候和耀斑带所在的位置符合得较好.有关这一结构和3维磁重联及耀斑关系的研究在近年来受到越来越多的关注.从QSL的理论出发,研究了2011年12月26日在活动区AR11384发生的一个C5.7级典型双带耀斑(事件1)和2015年6月22日发生在活动区AR12371处的一个M6.5级耀斑(事件2).结合SDO/AIA (Solar Dynamics Observatory/Atmospheric Imaging Assembly)观测到的多波段数据和SDO/HMI (Helioseismic and Magnetic Imager)观测到的矢量磁场数据,首先分别利用势场和非线性无力场对日冕的3维磁场结构进行了外推,并计算了活动区磁自由能的演化;然后基于势场和非线性无力场的外推结果计算了不同高度处磁压缩因子(magnetic squashing factor)Q的对数分布,并研究了不同高度磁准分界面与相应高度处观测到的耀斑带的演化关系.最后分析了2个耀斑事件的多波段演化特征,并计算得到事件2中磁力线的平均滑动速度在304 (A)波段和335 (A)波段分别为4.6 km.s-1和6.3 km.s-1.研究发现:计算得到的磁准分界面在色球和日冕中的位置和相应高度观测到的耀斑带的位置符合得较好,而且各层次的磁准分界面与相应层次的耀斑亮带在时间上也有近乎一致的演化行为,这突显出了磁准分界面理论在3维磁重联和耀斑研究中的作用,并证实事件2耀斑能量的释放可能是通过发生在QSL处的磁重联进行的,同时说明,研究QSL对于理解2维磁重联和3维磁重联本质联系是至关重要的.