两个太阳爆发事件中磁重联电流片的观测研究  

An Observational Research on Magnetic Reconnection Current Sheet Occurred in Two Solar Eruptions

作　　者：蔡强伟 吴宁[3] 林隽[1] 

机构地区：[1]中国科学院云南天文台昆明650011 [2]中国科学院大学北京100049 [3]云南师范大学旅游与地理科学学院昆明650031

出　　处：《天文学报》2015年第6期598-615,共18页Acta Astronomica Sinica

基　　金：973项目(2013CBA01503);国家自然科学基金项目(11273055,11333007);中国科学院先导专项B类项目(XDB09040202)资助

摘　　要：日冕物质抛射(Coronal Mass Ejection,CME)通常会将其后面区域中的磁场急剧拉伸,使得极性相反的磁力线相互靠近而形成磁重联电流片.磁重联电流片在爆发过程中,既是磁自由能迅速转化为热能、等离子动能和高能粒子束流的重要区域,又起着连接日冕物质抛射和耀斑的作用.2003年1月3日和11月4日的两次CME事件,在CME离开太阳表面附近之后,均有电流片被观测到.结合搭载在SOHO(Solar and Heliospheric Observatory)上的LASCO(Large Angle and Spectrometric Coronagraph)、UVCS(Ultraviolet Coronagraph Spectrometer)数据,以及大熊湖天文台和云南天文台的Hα资料,研究两次爆发事件的动力学特征,以及电流片的物理特性.电流片中高电离度粒子的存在,如Fe^(+17)、Si^(+11),表明电流片区域中温度高达3×10~6～5×10~6K.直接测量发现电流片的厚度在1.3×10~4～1.1×10~5km范围之间,并随时间先增大后逐渐减小.利用CHIANTI(ver 7.1)光谱代码,进一步计算得到2003年1月3日电流片中的电子温度和相应辐射量(Emission Measure,EM)的均值分别为3.86×10~6K和6.1×10^(24)cm^(-5).另一方面,利用SOHO/UVCS观测数据对2003年11月4日的CME爆发事件中的电流片进行分析,发现电流片呈现准周期性扭转运动.The coronal magnetic configuration is severely stretched by the disruption in the process of coronal mass ejection （CME）, pushing the magnetic fields of opposite polarity to approach one another, and creating a magnetic neutral region （current sheet） behind CME. Magnetic reconnection taking place inside the current sheet converts the magnetic energy into heat and kinetic energy of the plasma, and the kinetic energy of energetic particles. The role of the current sheet in this process is two-fold： the region where reconnection occurs, and connecting the flare to the associated CME. We studied the events of 2003 January 3 and 2003 November 4, respectively. Development of the current sheet was observed in both cases. We investigated the dynamic features of the two events, as well as physical properties of the current sheet, on the basis of analyzing the observational data from LASCO （Large Angle and Spectrometric Coronagraph） and UVCS （Ultraviolet Coronagraph Spectrometer） on board SOHO （Solar and Heliospheric Observatory）, and the Hc~ data from BBSO （Big Bear Solar Observatory） and YNAO （Yunnan Observatories）. The existence of ions with high ionization state, such as Fe＋17 and Si＋11, indicated a high temperature up to 3× 106 - 5 × 106 K. Direct measurements showed that the apparent thickness of the current sheet varies from 1.3 × 104 to 1.1 × 105 km, which increases first and then decreases with time. Using the CHIANTI code （v.7.1）, we further calculated the averages of the electron temperature and the corresponding emission measure in the current sheet of the 2003 January 3 event, which were about 3.86×106 K and 6.1 × 1024 cm-5, respectively. We also noticed that the current sheet twisted forth and back in a quasi-periodical fashion during the event on 2003 November 4 by analyzing the data from SOHO/UVCS.

关 键 词：太阳 日冕物质抛射 太阳 电流片 太阳 辐射量 太阳 紫外辐射 

分 类 号：P182[天文地球—天文学]