Magnetic field, helicity and the 2000 July 14 flare in solar active region 9077
Magnetic field, helicity and the 2000 July 14 flare in solar active region 9077
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DOI：
10.1046/j.1365-8711.2002.05345.x
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发表时间：
2002-05
影响因子：
4.8
通讯作者：
Hongqi Zhang
中科院分区：
文献类型：
--
作者：
Hongqi Zhang
本文利用不同太阳观测站的光球矢量磁图和TRACE卫星的日冕极紫外171-A图像，分析了2000年7月NOAA 9077活动区的非位磁场及其与电流（螺旋度）的关系。我们注意到磁场的剪切和挤压是某些耀斑产生区的两个重要指标，并可由太阳活动区NOAA 9077的一系列光球矢量磁象和EUV 171-A特征得到证实。太阳低层大气的磁切变、电流和电流螺旋度的变化为光球磁中性线附近磁场的释放提供了证据。发现2000年7月14日的“巴士底日”3B/5.7X耀斑是由不同磁环系统相互作用触发的，这与低层太阳大气螺旋磁场的抛射有关。大尺度日冕磁场的爆发晚于活动区强烈剪切的光球磁场和电流的衰减。
In this paper we analyse the non-potential magnetic field and the relationship with current (helicity) in the active region NOAA 9077 in 2000 July, using photospheric vector magnetograms obtained at different solar observatories and also coronal extreme-ultraviolet 171-A images from the TRACE satellite. We note that the shear and squeeze of magnetic field are two important indices for some flare-producing regions and can be confirmed by a sequence of photospheric vector magnetograms and EUV 171-A features in the solar active region NOAA 9077. Evidence on the release of magnetic field near the photospheric magnetic neutral line is provided by the change of magnetic shear, electric current and current helicity in the lower solar atmosphere. It is found that the ‘Bastille Day’ 3B/5.7X flare on 2000 July 14 was triggered by the interaction of the different magnetic loop systems, which is relevant to the ejection of helical magnetic field from the lower solar atmosphere. The eruption of the large-scale coronal magnetic field occurs later than the decay of the highly sheared photospheric magnetic field and also current in the active region.