摘要
利用国家天文台(北京和昆明)的射电频谱仪(频段为0.65~7.6GHz)和相关的NORH/17GHz射电以及TRACE/171^°A EUV和Yohkoh/SXT的观测资料,分析了2001/04/10和10/19的2个共生精细时间结构的稀有事件,这2个事件的射电爆发时间轮廓和观测特征相似,通过这2个事件的微波(17GHz)偏振观测资料的比较,发现这2个射电爆发均由包含多重(4极)磁结构的复杂活动区引起,特别指出这2个耀斑最后都导致了耀斑后相的分米波射电爆发(第二次触发耀斑),这可能是后环引起的射电爆发。它们都分别对应于双极磁位形,表明这两次触发耀斑是由相似的耀斑模型产生。2个分米波爆发可能是相似(homologous)耀斑的射电表现,可以推测这两次耀斑的驱动器可能皆是磁流浮现或对消(因为源区有新的单或双极出现或消失),而它们的触发器皆是由双极反向Y型位形(具有一个双极拱的单磁流系统)的磁重联,耀斑后环的演化是导致耀斑后相分米波射电爆发的必要条件。我们认为,这双带耀斑对应的宽带射电爆发辐射机制是回旋同步加速辐射过程,而耀斑后相的窄带分米波爆发的辐射机制是等离子体辐射过程.
Observational data of two radio events (2001/04/10 and 2001/10/19) associated with the fast time structures obtained with the spectrometers (0.65 - 7.6 GHz) at the National Astronomical Observatories, Chinese Academy of Sciences (Beijing and Yunnan) (NAOC) and NoRH/17GHz as well as TRACE/EUV ( 171^°A ) and Yohkoh/SXT are analyzed in this paper. The time profiles and observational characteristics of two radio events are similar. By comparison with the observational images of coronal magnetic polarities for these two events, it is found that the complex radio bursts are caused by the evolution of the active regions including multiply magnetic polarities and finally results in the decimetric radio bursts (secondary triggering) around the top of the post-flare loops. In particular, it is indicated that two decimetric radio bursts are attributed to the behavior of post-flare loops. The 2-step triggering flares ( corresponding to the broadband microwave and narrowband decimetric bursts) are corresponding to the bipolar magnetic configuration, respectively. This manifests that these two bursts are produced by the similar flare models. It is presumed that the 2-step triggering drivers of the flares are the magnetic flux emergence or cancellation (there are magnetic unipole or bipoles of new appearance or disappearance during the evolution of magnetic structures), while their triggers are the magnetic reconnection of bipole inverted ‘Y-type' configuration. It is thought that the emission mechanisms about the broad-band microwave and the narrowband decimetric radio bursts could be attributed to the gym-synchrotron emission and the plasma emission processes, respectively.
出处
《天文研究与技术》
CSCD
北大核心
2006年第3期247-257,共11页
Astronomical Research & Technology
基金
国家自然科学基金(No.10473020
10333030)
中国科学院2003年度"西部之光"人才培养计划基金支持
关键词
太阳
射电辐射
日冕磁结构
耀斑触发
Sun;radio burst
coronal magnetic structure
flare triggering