太阳耀斑显著的热和非热事件的统计特征

THE STATISTICAL CHARACTERISTICS OF PROMINENT THERMAL AND NON-THERMAL EVENTS IN SOLAR FLARES

本文利用GOES卫星和SMM卫星软、硬X射线耀斑观测资料,分析耀斑中软、硬X射线辐射流量的分布,发现太阳耀斑存在着显著的热事件(PT事件)和显著的非热事件(PNT事件),它们主要特征是:(1)PT事件为缓变型耀斑,PNT事件为脉冲型耀斑;(2)PT事件的硬X射线谱较软,PNT事件能谱较硬;(3)PNT事件非热能量释放速率比PT事件快3—10倍;(4)耀斑发展趋缓慢,PT事件中软X射线峰值流量越大;(5)耀斑中PNT事件约占60％,PT事件约占40％.最后定性讨论了产生PT和PNT事件的可能机制.

An analysis of the properties of soft and hard X-ray flux distribution in solar flares observed by GOES and SMM satellites shows that there are two distinct kinds of solar flare, i.e. the prominent thermal and non-thermal events. The main characteristics for these two kinds of event are: (1) the prominent thermal event is consisted of gradual type flares, while the prominent non-thermal event is impulsive ones; (2) the energy spectrum of hard X-ray is relatively 'soft' for the prominent thermal event and 'hard' for the non-thermal event; (3) the releasing rate of non-thermal energy for the prominent non-thermal event is 3-10 times larger than that for the thermal events; (4) for the prominent thermal event it seems that the slower is the evolution of flares, the larger is the peak flux of soft X-rays; (5) the prominent thermal and non-thermal events constitute respectively 40% and 60% of the solar flares. Finally, the possible mechanism responsible for the prominent thermal and non-thermal events is discussed.