2009年2月13日EUV波现象数值研究

Numerical Study of EUV Wave on 13 February 2009

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05:35 UT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EUV1/STEREOB195 A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247 km.s^(-1),数值模拟得到的EUV波速度为245 km·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.

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 A 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 A 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 247 km.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 observationsand confirm that EUV wave is a fast-mode MHD wave.