2009年2月13日EUV波现象数值研究

结合STEREO卫星的观测和三维磁流体力学数值模拟方法, 采用WSO (Wilcox Solar Observatory)磁场数据和势场源表面模型建立日冕初始磁场, 并在日面活动区加上时变的压强扰动, 对2009年2月13日05:35UT爆发的CME-EUV波(Coronal Mass Ejections-Extreme Ultraviolet wave, 日冕物质抛射-远紫外波)事件进行研究. 从COR1/STEREO-A图像判断, 此次CME前沿速度约340km·s-1, 角宽度约60°; 分析EUVI/STEREO-B 195 ?的差分图像, 可以看到, 环形亮环波前从活动区向四周传播, 亮环波前后面是日冕暗化区, 取四个方向的波前位置进行线性拟合可知, 该EUV波速度为247km·s-1, 数值模拟得到的EUV波速度为245km·s-1, 将计算结果采用IDL可视化后可以看到明显的亮环和暗区结构, 数值模拟结果与卫星观测相一致, 表明该EUV波现象是快磁声波. 

Numerical Study of EUV Wave on 13 February 2009

EUV wave is observed in the extreme ultraviolet spectrum as large-scale disturbances phenomenon, often accompanied by a coronal mass ejection. Besides, EUV wave is, when displayed in EUVI 195 ? difference image, a bright ring propagating outside with the subsequent spread of the dark zone. The disturbance can often cover the whole solar disk. The current study explores the CME-EUV wave event that occurred at 05:35UT on 13 February 2009, based on the STEREO satellite observations and the three-dimensional Magnetohydrodynamic (MHD) numerical simulation. We know this CME with 340km·s-1 front velocity and 60° angular width from the COR1/STEREO-A observations. Viewing in EUVI/STEREO-B 195? running difference images, a bright toroidal wave front propagates outside from the active region, with dimming area following the bright wave front. The fitting velocity of EUV wave from the observation data is 247km·s-1. The numerical simulation shows that the (fast-mode) wave, with legible bright front and dimming structure, propagates in a speed of 245km·s-1. The simulation results turn out to be consistent with the satellite observations and confirm that EUV wave is a fast-mode MHD wave.