耀斑日冕硬X射线源观测研究

An Observational Study on Coronal Hard X-ray Sources of Solar Flares

对于足点被日面边缘遮挡住的耀斑的观测研究是诊断日冕硬X射线辐射的一个重要方法.通过统计分析RHESSI(Reuven Ramaty High-Energy Solar SpectroscopicImager)卫星观测到的71个此类耀斑硬X射线源发现,前人提出的两类源,即日冕X射线辐射中热辐射与非热辐射源区空间分离较小的源和分离较大的源,在能谱、成像、光变曲线以及GOES持续时间等方面都没有显著的区别,其中辐射区的面积、耀斑总热能以及GOES持续时间与分离距离之间有很好的相关性.这些结果支持近年来提出的一些耀斑统一模型.同时也表明Masuda耀斑只是一类非常特殊的事件,不具有日冕硬X射线辐射的一般特征.

Observations of solar flares partially occulted by the solar limb provide a valuable diagnostics of coronal hard X-ray emissions due to the absence of generally dominant emissions from flare footpoints. In this paper, a statistical survey of 71 partially occulted flares observed by RHESSI （Reuven Ramaty High-Energy Solar Spectroscopic Imager） is presented. We find that two kinds of hard X-ray sources proposed previously are similar in the aspects of their photon spectra, images, light of the radiation region, the total thermal energy curves and GOES durations, and the scales and the GOES durations are correlated to the separations between the thermal source and the non-thermal source. These results are consistent with some of the unified models proposed in recent years, and indicate that the Masuda flare could not be typical in coronal hard X-ray emission.