Magnetic field topology of an active region
Magnetic field topology of an active region
复制标题
DOI：
10.1002/asna.2113110515
复制
发表时间：
1990
影响因子：
0.9
通讯作者：
J. Linke;B. Ioshpa;V. Selivanov
中科院分区：
文献类型：
--
作者：
J. Linke;B. Ioshpa;V. Selivanov
使用一系列光球纵向和矢量磁图以及 Hα 滤波器图和白光图像，估计了早期阶段弱耀斑活动区 AR 5420 的磁场的全局 3 维拓扑。作为此任务的物理模型，我们使用了无力磁场特性的假设。在预耀斑阶段已经识别出类似拱廊的磁场结构，并且在无电流场情况下已经存在明显的剪切配置。该系统可能是随后喷发的场对准电流系统的重要产生源。特别是在1984年6月22日至25日的观测期间，活动区域面积显着扩大，导致检测到的拱廊状系统出现更强的剪切力。以这种方式产生的大气电流和6月23日在这个地方出现的新通量产生的大幅扰动所引发的转变共同可能是观察到耀斑序列的原因。尽管 Hα 结构发生了变化，但随着观测时间的推移，场的整体无力特征并未发生显着变化。磁场的无力（几乎无电流）特性的不变性（一阶）仅与相对较小的耀斑的发生一致。
The global 3-dimensional topology of the magnetic field of the weakly flaring active region AR 5420 in the early phase has been estimated using a series of photospheric longitudinal and vector magnetogams together with Hα filtergrams and white-light images. As a physical model for this task, we have used the assumption ofa force-free magnetic field character. An arcade-like structure of the magnetic field has been identified in the preflare phase with an apparent sheared configuration already present in the current-free field case. This system might have been an important source of generation of a field-aligned current system for the eruptions that followed. That was, in particular, suggeted by a significant extension of the active region area in the observation period from June 22 to 25, 1984, that resulted in a stronger shear of the detected arcade-like system. The atmospheric electric currents generated in such a way and the transition triggered by a large-amplitude perturbation generated by new flux emergences on June 23 at this place together might be the reason of the sequence of flares observed. Despite the changes in the Hα structure, the global force-free character of the field did not change significantly over the time of observations. The invariance (in the first order) of the force-free (nearly current-free) character of the magnetic field is consistent with the occurrence of relatively small flares only.