Photospheric Magnetic Activities Responsible for Soft X-Ray Pointlike Microflares. I. Identifications of Associated Photospheric/Chromospheric Activities
Photospheric Magnetic Activities Responsible for Soft X-Ray Pointlike Microflares. I. Identifications of Associated Photospheric/Chromospheric Activities
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DOI：
10.1086/340998
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发表时间：
2002-08
期刊：
影响因子：
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通讯作者：
T. Shimizu;R. Shine;A. Title;T. Tarbell;Z. Frank
中科院分区：
文献类型：
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作者：
T. Shimizu;R. Shine;A. Title;T. Tarbell;Z. Frank
通过将Yohkoh软X射线图像与在La Palma同时获得的高分辨率磁图相结合，我们研究了负责软X射线微耀斑（活动区瞬态增亮）的光球磁特征。为了在光球和日冕之间建立可靠的对应关系，我们研究了16个X射线源尺寸小于10“的点状瞬变增亮，它们发生在La Palma视宁度很好的时期，尽管许多瞬变增亮是多环或单环结构的形式。在所研究的事件的一半，小规模的磁通量环的出现被发现在附近的瞬态增亮。这一半的六个事件表明，一个小规模的通量出现伴随着X射线增亮5-30分钟之前，它的发病。在另一半的研究事件中，没有发现明显的磁通量元素的演化变化与瞬态增亮。其中许多事件都是在相当强的磁场中发现的，如太阳黑子和孔隙，这意味着磁通量的小规模变化被强磁场掩盖或抑制。由连续图像中颗粒的局部互相关跟踪得到的水平等离子体流被抑制在某些X射线瞬态增亮的脚下。
By combining Yohkoh soft X-ray images with high-resolution magnetograms simultaneously obtained at La Palma, we studied photospheric magnetic signatures responsible for soft X-ray microflares (active-region transient brightenings). In order to have a reliable correspondence between the photosphere and the corona, we studied 16 pointlike transient brightenings with X-ray source size less than 10'' occurring during periods when the seeing was excellent at La Palma, although a lot of transient brightenings were in forms of multiple- or single-loop structures. In half of the studied events, small-scale emergences of magnetic flux loops are found in the vicinity of the transient brightenings. Six events of that half show that a small-scale flux emergence accompanies the X-ray brightening 5-30 minutes prior to its onset. In the other half of the studied events, no apparent evolutionary change of magnetic flux elements is found associated with the transient brightenings. Many of these events are found in rather strong magnetic fields, such as sunspots and pores, implying that small-scale changes of magnetic flux are obscured or suppressed by strong magnetic fields. The horizontal plasma flows derived from local cross-correlation tracking of granules in continuum images are suppressed at the feet of some X-ray transient brightenings.