Two-dimensional spectroscopy of a sunspot - III. Thermal and kinematic structure of the penumbra at 0$\farcs$5 resolution
Two-dimensional spectroscopy of a sunspot - III. Thermal and kinematic structure of the penumbra at 0$\farcs$5 resolution
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太阳黑子的二维光谱 - III。
DOI：
10.1051/0004-6361:20054768
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发表时间：
2006
影响因子：
6.5
通讯作者：
A. Tritschler
中科院分区：
文献类型：
--
作者：
L. B. Rubio;R. Schlichenmaier;A. Tritschler
我们使用非磁性 FeI 557.6 nm 线的高光谱和空间分辨率强度剖面研究太阳黑子半影的热学和运动学配置。该数据集是使用 2D 太阳光谱仪 TESOS 获取的。使用具有物理量梯度的单组分模型大气来反转剖面。从这个反演中，我们获得了温度深度、视线速度和半影中微湍流的分层。我们的结果表明，负责半影丝的物理机制优先在较低的光球层中运行。该光斑位于日心角 23° 处，与边缘侧相比，在中心侧半影中表现出更大的连续强度，这意味着 log τ 500 = 0 时的平均温差为 100-150 K。我们研究了当在谱线翼中观察到太阳黑子时，在内半影中出现的亮环的性质。这表明亮环并不反映中间光球层的温度升高。从反演中检索到的视线速度用于确定光球层中不同高度处的流动几何形状。流速和流动角都随着光学深度和径向距离的增加而增加。在中半影和外半影中检测到下降流，但仅在深层中检测到（log τ 500 > -1.4）。我们证明，从反演中检索到的速度分层与半影通量管引导安歇德流的想法是一致的。最后，我们表明，较大的埃弗谢德流与内部中心侧半影中较亮的连续介质强度相关。然而，暗结构也与重要的安歇德流有关。这使我们认为，在 0."5 分辨率下看到的亮丝和暗丝不是单独的流道，而是它们的集合。我们的分析强调了非常高的空间分辨率光谱和光谱偏振测量对于更好地了解太阳黑子半影的重要性。
We investigate the thermal and kinematic configuration of a sunspot penumbra using high spectral and spatial resolution intensity profiles of the non-magnetic FeI 557.6 nm line. The data set was acquired with the 2D solar spectrometer TESOS. The profiles are inverted using a one-component model atmosphere with gradients of the physical quantities. From this inversion we obtain the stratification with depth of temperature, line-of-sight velocity, and microturbulence across the penumbra. Our results suggest that the physical mechanism(s) responsible for the penumbral filaments operate preferentially in the lower photosphere. The spot, located at an heliocentric angle of 23°, exhibits larger continuum intensities in the center-side penumbra as compared with the limb side, which translates into an average temperature difference of 100-150 K at log τ 500 = 0. We investigate the nature of the bright ring that appears in the inner penumbra when sunspots are observed in the wing of spectral lines. It is suggested that the bright ring does not reflect a temperature enhancement in the mid photospheric layers. The line-of-sight velocities retrieved from the inversion are used to determine the flow geometry at different heights in the photosphere. Both the flow speed and flow angle increase with optical depth and radial distance. Downflows are detected in the mid and outer penumbra, but only in deep layers (log τ 500 > -1.4). We demonstrate that the velocity stratifications retrieved from the inversion are consistent with the idea of penumbral flux tubes channeling the Evershed flow. Finally, we show that larger Evershed flows are associated with brighter continuum intensities in the inner center-side penumbra. Dark structures, however, are also associated with significant Evershed flows. This leads us to suggest that the bright and dark filaments seen at 0."5 resolution are not individual flow channels, but a collection of them. Our analysis highlights the importance of very high spatial resolution spectroscopic and spectropolarimetric measurements for a better understanding of sunspot penumbrae.