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，取得了重大进展。Yohkoh软X射线望远镜揭示了太阳日冕是高度瞬态的，与之前由Skylab建立的日冕或多或少是静态的观点形成对比。Yohkoh的数据还表明，这些瞬态现象是由于磁重联。主要的科学结果概括如下：1.瞬变增亮（微耀斑）的发生率分布是总强度的函数。2.我们发现冕洞的温度与活动区以外的宁静太阳的温度一样高。3.我们证实了Skylab发现的标度律。标度律关系到稳定日冕环的三个关键物理参数（峰值温度、压力和环长）。4.提出了一种利用重联点流出产生场向电流的新理论。强电流可以沿场线沿着产生电势，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.