PHOTOSPHERIC FLUX CANCELLATION AND THE BUILD-UP OF SIGMOIDAL FLUX ROPES ON THE SUN
PHOTOSPHERIC FLUX CANCELLATION AND THE BUILD-UP OF SIGMOIDAL FLUX ROPES ON THE SUN
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DOI：
10.1088/0004-637x/759/2/105
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发表时间：
2011-05
期刊：
影响因子：
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通讯作者：
A. Savcheva;A. Savcheva;L. Green;A. A. Ballegooijen-A.;E. DeLuca
中科院分区：
文献类型：
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作者：
A. Savcheva;A. Savcheva;L. Green;A. A. Ballegooijen-A.;E. DeLuca
在这项研究中，我们探讨了光球通量抵消的情况，这是衰变活动区域中 S 形磁通绳的主要形成机制。我们分析了磁图和 X 射线观测结果，以及观测到的 S 形区域的数据驱动的非线性无力场 (NLFFF) 模型，以检验这一想法。我们通过 MDI 磁力图测量了该区域的总磁通和取消磁通，以及三个 S 形曲线（2007 年 2 月、2007 年 12 月和 2010 年 2 月）的建模 NLFFF 磁绳的轴向和极向磁通含量。我们推断，大多数模型磁绳中的极向磁通和轴向磁通之和约为取消磁通的 60%–70%，占该区域总磁通的 30%–50%。磁通测量和磁场结构分析表明，S 型曲线首先形成表现为剪切拱廊的强轴向场，然后随着磁通抵消的进行，形成长 S 形磁力线，从而形成极向磁通。此外，S 形磁力线的凹陷位于从 MDI 磁力图中识别出的磁通抵消位置。我们发现，对于所有三个区域来说，视线积分自由能也集中在这些位置，这些自由能在喷发过程中可以被释放。与耀斑相关的增亮和耀斑环与 X 线拓扑的位置一致，该 X 线拓扑在最强烈的通量抵消处形成。
In this study we explore the scenario of photospheric flux cancellation being the primary formation mechanism of sigmoidal flux ropes in decaying active regions. We analyze magnetogram and X-ray observations together with data-driven non-linear force-free field (NLFFF) models of observed sigmoidal regions to test this idea. We measure the total and canceled fluxes in the regions from MDI magnetograms, as well as the axial and poloidal flux content of the modeled NLFFF flux ropes for three sigmoids—2007 February, 2007 December, and 2010 February. We infer that the sum of the poloidal and axial flux in the flux ropes for most models amounts to about 60%–70% of the canceled flux and 30%–50% of the total flux in the regions. The flux measurements and the analysis of the magnetic field structure show that the sigmoids first develop a strong axial field manifested as a sheared arcade and then, as flux cancellation proceeds, form long S-shaped field lines that contribute to the poloidal flux. In addition, the dips in the S-shaped field lines are located at the sites of flux cancellation that have been identified from the MDI magnetograms. We find that the line-of-sight-integrated free energy is also concentrated at these locations for all three regions, which can be liberated in the process of eruption. Flare-associated brightenings and flare loops coincide with the location of the X-line topology that develops at the site of most vigorous flux cancellation.