两冕流间CME事件数值模拟的改进

IMPROVEMENT ON THE CME NUMERICAL SIMULATION OF CME BETWEEN TWO STREAMERS

通过偶极子场和六极子场适当叠加,改进猜解磁场,使猜解磁场在太阳南北极符号相反,然后采用理想磁流体力学方程组(MHD),由猜解磁场与太阳风流动相互作用计算出稳态自洽解,得到定性上与观测比较接近的具有两个冕流的背景结构.在两个冕流间采用具有同心圆磁场位形的触发模型触发CME事件,研究CME的日冕传播特征.模拟结果表明,CME被约束在两冕流间传播,CME闭磁场位形和磁云横截面磁场位形相似,可以解释1 AU处观测磁云的部分特征;在CME附近,存在压力和Lorentz力起主要作用的区域,这可以为分析1 AU处CME事件的观测数据提供帮助.

The solar magnetic field is improved by properly combining a dipole and a hexapole to make the polarity at two solar poles opposite. The self-consistent steady state with two streamers, satisfying observation qualitatively, is obtained by long time interaction between the initial combined potential magnetic field and solar wind flow. Then the CME triggering model with concentrically circular closed magnetic field structure is taken to trigger CME between two streamers for research about CME propagating features near corona. The numerical result shows that the CME event is confined by the two streamers to propagate between them and the closed CME magnetic field structure is similar to that in the section of magnetic cloud, which can explain some features of magnetic cloud observed at 1 AU. Moreover, it is found that there exist some areas, where pressure and Lorentz force dominate Row, which could be helpful for analysis of CME event data observed at 1 AU.