活动区NOAA6891的耀斑分析

ANALYSIS OF FLARES IN ACTIVE REGION NOAA 6891

本文分析了１９９１年１０月的一个大δ型活动区的黑子演化和耀斑产生的位置及可能原因，发现该活动区８９％的耀斑产生在两个磁中性线旁，两磁中性线处皆有较大的磁横场和剪切．在Ｈα中─中性线处观测到暗条由于黑子的挤压运动而变得剪切成“Ω”型；另一中性线处观测到纤维束较大的变化，有时明显能观测到磁绳结构．观测表明：大耀斑的爆发与磁场横向分量和磁剪切的大小没有明显的关系，而新浮磁通量和引起的磁对消可能是触发本活动区大耀斑的原因之一．我们首次观测到相反极性的黑子处于同一本影内，这样的磁位形可能与本活动区２４日和２７日观测到的两个白光耀斑有关．

The possible reason and position of the flares occurrence and the evolution of sunspots in a large δ-type active region in Oct.1991 is analysed.It is found 89 percent flares in this region occur by the two neutral lines where large magnetic transverse field and shear is observed. In the Ha filtergrams,the filament becomes sheared and turns into an Ω-type at one neutral line due to the successive extrusion motion and development of the sunspots;the qinck variation of a bundle of flbrils is observed at another neutral line. Sometimes the magnetic rope structure can be clearly seen. Our results show the eruption of large flares have nothing to do with the magnetic transverse field and shear. The new emerging flux and its resulting magnetic concellation may be one of the possible reason triggering the large flares. This was for the first time that we observed the sunspots with opposite polarities within one umbra. Such a magnetic configuration may have some relationship with the observed white light flares on Oct. 24 and Oct. 27.