Two magnetic components in sunspot penumbrae
Two magnetic components in sunspot penumbrae
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DOI：
10.1051/0004-6361:20041277
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发表时间：
2004-11
影响因子：
6.5
通讯作者：
L. B. Rubio;H. Balthasar;M. Collados
中科院分区：
文献类型：
--
作者：
L. B. Rubio;H. Balthasar;M. Collados
通过对三条红外谱线在1565 nm处的Stokes剖面进行反演，研究了太阳黑子半影的磁场和运动学构型。我们使用一个双组分模式大气来描述，至少在一阶，半影的未解析结构。观察到的Stokes剖面被成功拟合，包括那些表现出异常形状的。反演的结果与Solanki & Montavon（1993）提出的半影是由嵌入在更垂直的背景磁场中的几乎水平的磁通管形成的观点一致。除了最外层的半影外，这些管具有比背景弱的场，并且携带了大部分的埃弗舍流。我们描述了磁场矢量和速度矢量在这些大气分量中的径向变化。在半影中部及更远的地方，可以看到磁场和管道中的流体返回到太阳表面。在半影的任何地方，磁场矢量和速度矢量在描述半影通量管的分量中都有一个完美的对齐。我们发现Evershed流在外半影的许多地方是超临界的，在太阳黑子外边界附近的一些地方是超音速的。基于这些反演，我们认为，由简单单分量模型推断的平均磁场倾角和强度的方位角波动是由填充因子（即磁通管占用的分辨率单元的分数面积）的波动引起的，而不是由背景或磁通管大气的固有磁性和运动学特性的变化引起的。同时，我们也证实了Muller等人（2002）提出的磁场方位角跳变来解释观测到的红外光线净圆偏振。
The magnetic and kinematic configuration of sunspot penumbrae is investigated by performing an inversion of the Stokes profiles of three infrared lines at 1565 nm. We use a two-component model atmosphere to describe, at least to first order, the unresolved structure of the penumbra. The observed Stokes profiles are successfully fitted, including those exhibiting abnormal shapes. The results of the inversion are consistent with the idea that the penumbra is formed by almost horizontal flux tubes embedded in a more vertical background magnetic field, as proposed by Solanki & Montavon (1993). The tubes possess weaker fields than the background except in the very outer penumbra, and carry most of the Evershed flow. We characterize the radial variation of the magnetic field vector and the velocity vector in these atmospheric components. In the middle penumbra and beyond, the magnetic field and the flow in the tubes are seen to return to the solar surface. Everywhere in the penumbra, there is a perfect alignment of the magnetic field vector and the velocity vector in the component describing the penumbral flux tubes. We find that the Evershed flow is supercritical in many places of the outer penumbra, and supersonic at some locations near the outer sunspot boundary. Based on these inversions, we suggest that the azimuthal fluctuations in the average magnetic field inclination and strength inferred from simple one-component models are caused by fluctuations in the filling factor (i.e., the fractional area of the resolution element occupied by flux tubes), not by changes in the intrinsic magnetic and kinematic properties of the background or the flux-tube atmospheres. Also, we confirm the jump of magnetic field azimuth proposed by Muller et al. (2002) to explain the observed net circular polarization of infrared lines.