嵌套闭磁场结构内CME产生和传播的数值模拟  

Numerical Simulation of CME Initiation and Propagation From a Streamer Containing Nested Close Magnetic Field Structures

作　　者：叶占银[1] 魏奉思[1] 王赤[1] 冯学尚[1] 钟鼎坤[1] 

机构地区：[1]中国科学院空间科学与应用研究中心,北京100080

出　　处：《空间科学学报》2005年第4期241-247,共7页Chinese Journal of Space Science

基　　金：国家自然科学基金项目(40274052;40336053;40204009)中国科学院百人工程(2014105S)共同资助

摘　　要：给出了特殊类型的日冕物质抛射(CME)数值模拟定性结果,这种CME核心闭磁场结构前半部分磁力线的方向与太阳整体偶极场磁力线的方向相反.计算结果表明,这种CME核心闭磁场结构磁力线与太阳整体偶极场反向磁力线之间存在过渡磁场结构,在向外传播时过渡磁场结构所占的面积逐渐增大.这一结果可以用来解释飞船为什么能够观测到一类双极磁云,这类磁云前半部分磁场方向与太阳整体偶极场方向相反.为了模拟这一数值结果,强调需要采用包含嵌套闭磁场的冕流背景结构,并在合适的位置触发CME.Qualitative numerical result of a special type of Coronal Mass Ejection (CME) is presented. The magnetic field direction in front half part of central closed magnetic field of the CME is opposite to that of the solar global dipole. Numerical result shows that: between the two anti-directional magnetic field lines of the CME magnetic field and the solar global dipole, there exists a transitional magnetic field structure, the area scale of which becomes gradually large when CME propagates outward. The numerical result may explain why spacecrafts can observe a type of bipolar magnetic cloud, in front half of which, the magnetic field direction is opposite to that of the solar global dipole. To obtain the numerical result, a background streamer with nested close magnetic field lines in it plays a central role for the CME initiation and propagation. The background steady state solution is approached by a long time interaction between a potential magnetic field and Parker solar wind solution. The potential magnetic field is obtained by properly combining a dipole and a hexapole. Because for the dipole, interaction between the potential magnetic field and solar wind can not open the dipole up and a streamer containing nested close magnetic field structures for triggering the CME at a suitable position forms finally.

关 键 词：太阳风 日冕物质抛射 MHD方程组 

分 类 号：P353[天文地球—空间物理学]