Study of Solar Flare and Corona by 「Yohkoh」 Soft X-ray Telescope

利用Yohkoh卫星研究太阳耀斑和日冕已取得重大进展。Yohkoh软X射线望远镜显示，日冕是高度瞬变的，而不是SkyLab之前建立的日冕或多或少是静态的观点。Yohkoh的数据还表明，这些瞬变现象是由于磁重联造成的。主要的科学结果总结如下：1.瞬变亮化(微耀斑)具有作为总强度函数的幂律发生分布。有可能是微耀斑的集合对持续日冕的加热有贡献。2.我们发现日冕空洞的温度与活动区外安静的太阳的温度一样高。3.我们用SkyLab证实了所发现的标度定律。标度定律与稳定日冕环路的三个关键物理参数(峰值温度、压力和环长)有关。4.我们提出了一个新的理论来产生与重联位置流出的场向电流。强电流会沿着电场线产生电势，导致电子加速。

Studies of solar flares and corona with Yohkoh satellite Significant advances have been obtained with this research. Yohkoh Soft X-ray Telescope revealed thet solar corona is highly transient in contrast to the previous view established by Skylab that the corona is more or less static. Yohkoh data also showed that these transient phenomena are due to magnetic reconnection. The prime scientific results are summarized below :1.Transient brightenings (micro flares) have a power-law occurrence distribution as a function of the total intensity. There is a possibility that the ensemble of micro flares contributes to the heating of the persistent corona.2.We found that the temperature of coronal holes is as high as those of the Quiet Sun outside active regions.3.We confirmed the scaling-laws discovered with Skylab. The scaling law relates three key physical parameters (peak temperature, pressure and loop-length) of steady coronal loops.4.We proposed a new theory to generate the field-aligned current with the outflow from the reconnection site. The intense current can generate electric potential along the field lines, resulting in the electron acceleration.