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arXiv 1012.3503astro-ph.SR
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太阳活动区自洽非线性无力模型的实现

Achieving Self-Consistent Nonlinear Force-free Modeling of Solar Active Regions

M. S. Wheatland, K. D. Leka

摘要:

根据2007年4月30日Hinode卫星观测得到的光球矢量磁图,考虑到边界数据的不确定性,并使用改进的多仪器数据合并方法,构造了NOAA太阳活动区AR 10953日冕磁场的非线性无力解。该解决方案演示了Wheatland & Regnier(2009)的“自洽”程序,首次包括不确定性。自洽程序解决了光球矢量磁图数据与无力模型不一致的问题,特别是垂直电流密度的边界条件被过度指定,并允许两个不同的非线性无力解决方案的建设。该程序修改的边界条件,电流密度在一系列的周期,直到两个非线性无力的解决方案同意。因此,它构建了一个精确的单一解决方案的无力模型,边界值接近,但不完全匹配,矢量磁图数据。包含不确定性在具有较小不确定性的点处更紧密地保持边界条件。自洽的解决方案获得的活动区AR 10953是显着的非势,与磁能E/E_0 = 1.08,其中E_0是参考电位(电流自由)磁场的能量。自洽的解决方案被证明是强大的,对在每个周期的两个无力模型的建设的细节的变化。这表明,可靠的非线性力自由活动区的建模是可能的,如果矢量磁图边界数据的不确定性。

英文摘要:

A nonlinear force-free solution is constructed for the coronal magnetic field in NOAA solar active region AR 10953 based on a photospheric vector magnetogram derived from Hinode satellite observations on 30 April 2007, taking into account uncertainties in the boundary data and using improved methods for merging multiple-instrument data. The solution demonstrates the "self-consistency" procedure of Wheatland & Regnier (2009), for the first time including uncertainties. The self-consistency procedure addresses the problem that photospheric vector magnetogram data are inconsistent with the force-free model, and in particular that the boundary conditions on vertical electric current density are over-specified and permit the construction of two different nonlinear force-free solutions. The procedure modifies the boundary conditions on current density during a sequence of cycles until the two nonlinear force-free solutions agree. It hence constructs an accurate single solution to the force-free model, with boundary values close, but not matched exactly, to the vector magnetogram data. The inclusion of uncertainties preserves the boundary conditions more closely at points with smaller uncertainties. The self-consistent solution obtained for active region AR 10953 is significantly non-potential, with magnetic energy E/E_0 = 1.08, where E_0 is the energy of the reference potential (current-free) magnetic field. The self-consistent solution is shown to be robust against changes in the details of the construction of the two force-free models at each cycle. This suggests that reliable nonlinear force-free modeling of active regions is possible if uncertainties in vector magnetogram boundary data are included.

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