基于MDI/SOHO合成图的全球磁场外推(英文)  

Global Magnetic Extrapolation Based on the Synoptic Map of MDI/SOHO

作　　者：刘煜[1] 张洪起[1] 

机构地区：[1]中国科学院国家天文台,北京100012

出　　处：《云南天文台台刊》2002年第4期1-9,共9页Publications of the Yunnan Observatoty

基　　金：国家自然科学基金(19791090,10073013)资助项目.

摘　　要：用势场方法和格林函数解构造了三维日冕磁场。相关的边界条件是所观测的光球磁场以及光球上2.6个太阳半径的开放场(源表面)。所用的光球数据来自高精度的MDI/SOHO观测(2″/像素,1桢/98min)。这种外推方法可以用来分析太阳大事件在大尺度上的可能触发机制。作为一个例子,我们分析了活动区NOAA9077的外推日冕场,发现它们的形态与EIT/SOHO的日冕观测相符很好。结合全日面Hα演化,我们推测来自活动区9082的一次激波扰动应该是导致2000年7月14日大耀斑和日冕物质抛射的触发原因,该扰动沿着外推所得到的一个磁环系统直接传到大耀斑爆发位置。We use a potential-field method to reconstruct the 3-D global coronal magnetic fields based on a Green's function solution. The related sources for the magnetic field are the observed photospheric field and the opened field at the source surface 2.6R⊙ above the photosphere. The photospheric data are the high resolution synoptic maps of the MDI/SOHO (2″/pix,1 frame/96mins).We apply this extrapolation method to analyze possible triggers for major events in large scale. As an example, the extrapolated coronal field of the active region NOAA 9077 is demonstrated.We find a good correlation between the reconstructed morphology and that of the EIT/SOHO observation.Combined with the full-disk Hα evolution we infer that a shock wave, which originated from the AR 9082 and propagated along an extrapolated loop system directly to the place of the flare,should be the direct trigger of the large event on July 14,2000.

关 键 词：太阳磁场 日冕 势场 格林函数解 触发机制 

分 类 号：P182.62[天文地球—天文学]