ON THE BRIGHTENING PROPAGATION OF POST-FLARE LOOPS OBSERVED BY TRACE
ON THE BRIGHTENING PROPAGATION OF POST-FLARE LOOPS OBSERVED BY TRACE
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DOI：
10.1088/0004-637x/690/1/347
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发表时间：
2008-09
期刊：
影响因子：
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通讯作者：
Leping Li;Jun Zhang
中科院分区：
文献类型：
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作者：
Leping Li;Jun Zhang
利用1998年5月至2006年12月过渡区和日冕探测器卫星观测到的耀斑数据，选取了171 nm和195 nm波长的190个耀斑事件（151个M级，39个X级），这些耀斑事件显示了耀斑后环（PFL）。在190个事件中，有124个事件显示出耀斑带（FR），由1600张照片观察到。我们研究了沿着中性线的FFL的增亮的传播以及垂直于中性线的FRs的分离。观测结果表明，初始增亮的PFL的足点总是与光球磁场的变化相联系。在大多数情况下，FR的长度范围为20 μ m至170 μ m。增亮的传播时间为10至60分钟，FR的分离时间为10至70分钟。传播速度和分离速度分别为3 - 39 km s-1和3 - 15 km s-1。耀斑的传播速度和分离速度都与耀斑的强度和耀斑的长度有关。看来，传播和分离是动态耦合的;传播速度越大，分离越快。此外，更大的传播速度对应于更大的减速度（或加速度）。这些PFLs显示三种类型的传播模式。在第一类传播，其中包括约一半的所有事件，增亮开始在一组的PFLs的中间部分，并向其两端双向传播。对于II型，包括所有事件的30%，增亮首先出现在一组PFL的一端，然后传播到另一端。其余事件属于III型传播，其显示初始增亮发生在两组（或两组以上）PFL上的两个（或两个以上）位置，然后沿中性线沿着双向传播。这三种类型的传播模式可以用三维磁重联模型来解释。
Examining flare data observed by Transition Region and Coronal Explorer satellite from 1998 May to 2006 December, we choose 190 (151 M-class and 39 X-class) flare events which display post-flare loops (PFLs), observed by 171 Å and 195 Å wavelengths. One-hundred twenty-four of the 190 events exhibit flare ribbons (FRs), observed by 1600 Å images. We investigate the propagation of the brightening of these PFLs along the neutral lines and the separation of the FRs perpendicular to the neutral lines. Observations indicate that the footpoints of the initial brightening PFLs are always associated with the change of the photospheric magnetic fields. In most of the cases, the length of the FRs ranges from 20 Mm to 170 Mm. The propagating duration of the brightening is from 10 to 60 minutes, and from 10 to 70 minutes for the separating duration of the FRs. The velocities of the propagation and the separation range from 3 to 39 km s−1 and 3 to 15 km s−1, respectively. Both the propagating velocities and the separating velocities are associated with the flare strength and the length of the FRs. It appears that the propagation and the separation are dynamically coupled; the greater the propagating velocity, the faster the separation. Furthermore, a greater propagating velocity corresponds to a greater deceleration (or acceleration). These PFLs display three types of propagating patterns. In type I propagation, which includes about half of all the events, the brightening begins at the middle part of a set of PFLs, and propagates bidirectionally toward both of its ends. For type II, including 30% of all events, the brightening first appears at one end of a set of PFLs, then propagates to the other end. The remaining events belong to type III propagation, which display the initial brightening taking place at two (or more than two) positions on two (or more than two) sets of PFLs, then propagating bidirectionally along the neutral line. These three types of propagating patterns can be explained by a three-dimensional magnetic reconnection model.