大型太阳活动区磁场的一个模型  

A MODEL OF MAGNETIC FIELDS IN A SUPER SOLAR ACTIVE REGION

作　　者：季海生[1] 宋慕陶[1] 

机构地区：[1]中国科学院紫金山天文台,南京210008

出　　处：《天文学报》2000年第3期257-269,共13页Acta Astronomica Sinica

基　　金：中国科学院"九五"基础性研究重大项目! (KJ951 1 3 0 5)

摘　　要：用时间缓变的非线性无力场模拟超级活动区 (弧岛式大型δ黑子 )的磁场位形 .这个复杂磁场包含了向量磁场的主要观测特征 :正负磁流极端不平衡性 (正负磁流之比为 1∶6) ,U形磁反变线 ,局域磁场的二极子、四极子差异性 .模拟结果可用来解释一些观测结果 :( 1 )大耀斑主要产生在U形中性线的磁性混杂区或四极子区 .( 2 )U形反变线的准双极性区几乎没有大耀斑或耀斑很小 .( 3)活动区内部的大型旋转运动和磁浮运动会导致四极子场磁拓扑分离面产生大型电流片 ,从而引起强烈磁重联 ,产生大耀斑 .计算非线性无力场方法是Woodsbury松弛法在极坐标下的自然推广 ,回避了通常的病态解问题 ,它使线性和非线性无力场解协调起来 ,有一个连续和平滑的过渡 .Within the framework of nonlinear force free fields, the authors try to model the magnetic field configurations of a super active region (with large island sunspots). They choose to represent the magnetic fields in terms of Eulerian potential variables and employ Woodsbury's relaxation method. This complicated magnetic field model includes the main characteristics of observed vector magnetic field of a super active region: i.e. the large magnetic flux imbalance, the U shaped inversion line and the difference between bipolar and quadrupolar magnetic fields. This model enables us to understand the following phenomena: (1) Major flares often occur near the U shaped inversion line where the magnetic filed configurations are qradrupolar. (2) No major flares occur near the U shaped inversion line where the magnetic field configurations are quasi bipolar. (3) Under large scale rotational motion and flux emergence the separatrix in a quadrupole can produce a large current sheet where strong magnetic reconnection takes place.

关 键 词：MHD 磁场 太阳活动区 

分 类 号：P182.7[天文地球—天文学]