Are Heating Events in the Quiet Solar Corona Small Flares? Multiwavelength Observations of Individual Events
Are Heating Events in the Quiet Solar Corona Small Flares? Multiwavelength Observations of Individual Events
复制标题
安静日冕中的加热事件是单个事件的多波长观测吗？
DOI：
10.1023/a:1005255608792
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发表时间：
1999
期刊：
影响因子：
2.8
通讯作者：
A. Benz
中科院分区：
文献类型：
--
作者：
S. Krucker;A. Benz
在宁静区域日冕发射测量的暂时增强已被证明构成了一个重要的能量输入。这里研究了一些相对较大的事件在过渡区线和无线电发射的同时增亮。相关的排放量进行了讨论和测试的特征，已知的全尺寸脉冲耀斑在活跃地区。加热事件和耀斑被发现有许多共同的属性，包括（i）相关的偏振无线电发射，它通常先于发射测量峰（Neupert效应），有时有一个非热谱，和（ii）相关的，并经常在O V和He I发射峰。另一方面，加热事件也不同于脉冲耀斑：（i）在一半的情况下，它们的厘米波射电辐射显示出与热辐射一致的光谱，（ii）回旋同步辐射与估计的热软X射线辐射的比率小于耀斑，（iii）O v过渡区线中的相关辐射显示出红移和蓝移，分别表示上升阶段的上升流和衰减阶段的下降流。尽管如此，这些差异似乎主要是定量的，所分析的热能在1026 erg左右的加热事件原则上可以被认为是微耀斑或大的纳米耀斑，因此是规则耀斑的小版本。
Temporary enhancements of the coronal emission measure in a quiet region have been shown to constitute a significant energy input. Here some relatively large events are studied for simultaneous brightenings in transition region lines and in radio emission. Associated emissions are discussed and tested for characteristics known from full-sized impulsive flares in active regions. Heating events and flares are found to have many properties in common, including (i) associated polarized radio emission, which usually precedes the emission measure peak (Neupert effect) and sometimes has a non-thermal spectrum, and (ii) associated and often preceding peaks in O v and He i emission. On the other hand, heating events also differ from impulsive flares: (i) In half of the cases, their radio emission at centimeter waves shows a spectrum consistent with thermal radiation, (ii) the ratio of the gyro-synchrotron emission to the estimated thermal soft X-ray emission is smaller than in flares, and (iii) the associated emission in the O v transition region line shows red shifts and blue shifts, indicating upflows in the rise phase and downflows in the decay phase, respectively. Nevertheless, the differences seem to be mainly quantitative, and the analyzed heating events with thermal energies around 1026 erg may in principle be considered as microflares or large nanoflares, thus small versions of regular flares.