A GEOMETRICAL HEIGHT SCALE FOR SUNSPOT PENUMBRAE
A GEOMETRICAL HEIGHT SCALE FOR SUNSPOT PENUMBRAE
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太阳黑子半影的几何高度尺度
DOI：
10.1088/0004-637x/720/2/1417
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
V. Martínez Pillet
中科院分区：
文献类型：
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作者：
K. Puschmann;B. Ruiz Cobo;V. Martínez Pillet
对半影细丝的光谱偏振观测的反演在光学深度尺度上提供了不同物理量的分层。但是，如果不建立几何高度比例尺，就无法推导出它们的三维几何结构。这对于正确理解半影大气中物理性质的空间变化，以及能够解释观测到的半影亮度的机制至关重要。这项工作的目的是通过最小化磁场矢量的散度和由力平衡方程施加的静态平衡偏差（包括压力梯度、重力和洛伦兹力）来确定半影中的全球几何高度尺度。光学深度模型是利用日野卫星上的太阳光学望远镜对活动区域的光谱偏振数据进行反演而得到的。利用遗传算法确定几何高度推断的边界条件。检索的几何高度尺度允许在每个像素处评估威尔逊凹陷和每个高度处物理量的相关性。我们的结果适合于未梳理的半影场景，即由具有通道质量流的磁通管组成的半影，与背景场相比，其磁场更弱，更水平。上升的物质比周围的物质更热，密度也更大。我们没有发现在内半影区分析的翻转对流或无场区域的证据。如果根据反演结果外推z =−75 km以下的物理量，则可以用Evershed气流携带的上升质量的能量传递来解释半影亮度。
Inversions of spectropolarimetric observations of penumbral filaments deliver the stratification of different physical quantities in an optical depth scale. However, without establishing a geometrical height scale, their three-dimensional geometrical structure cannot be derived. This is crucial in understanding the correct spatial variation of physical properties in the penumbral atmosphere and to provide insights into the mechanism capable of explaining the observed penumbral brightness. The aim of this work is to determine a global geometrical height scale in the penumbra by minimizing the divergence of the magnetic field vector and the deviations from static equilibrium as imposed by a force balance equation that includes pressure gradients, gravity, and the Lorentz force. Optical depth models are derived from the inversion of spectropolarimetric data of an active region observed with the Solar Optical Telescope on board the Hinode satellite. We use a genetic algorithm to determine the boundary condition for the inference of geometrical heights. The retrieved geometrical height scale permits the evaluation of the Wilson depression at each pixel and the correlation of physical quantities at each height. Our results fit into the uncombed penumbral scenario, i.e., a penumbra composed of flux tubes with channeled mass flow and with a weaker and more horizontal magnetic field as compared with the background field. The ascending material is hotter and denser than their surroundings. We do not find evidence of overturning convection or field-free regions in the inner penumbral area analyzed. The penumbral brightness can be explained by the energy transfer of the ascending mass carried by the Evershed flow, if the physical quantities below z = −75 km are extrapolated from the results of the inversion.