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arXiv 1207.2020astro-ph.SR
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Ca II H和K的翼作为光球诊断和一维光球模拟的可靠性

The wings of Ca II H and K as photospheric diagnostics and the reliability of one-dimensional photosphere modeling

V. A. Sheminova

摘要:

Ca II H和K线的延伸翼提供了对太阳光球和其他冷恒星的温度分层的出色诊断,这要归功于它们的LTE不透明度和源函数以及它们的大跨度形成高度。本研究的目的是校准使用的H和K翼在一维空间平均光谱的解释,并在推导每像素分层解析光谱。我使用太阳对流的多维模拟来合成H和K机翼,从这些机翼导出一维模型,就像它们被观察到一样,并将所得模型与实际模拟输入进行比较。我发现,从合成的翅膀构造的空间平均模型一般匹配的模拟平均值很好,除了最深层的光球大的热不均匀性和普朗克函数的非线性给出了很大的误差。不均匀性越大,后者越大。强网络场的存在增加了这种不均匀性。在平静的光球条件下,温度超过200 K。一维分层适合的离散结构,如造粒和小规模的磁浓度给出了令人满意的结果与错误,主要是由于陡峭的温度梯度和温度随深度的突然变化。我的结论是分层建模使用的H和K翼是一个有用的技术,太阳高分辨率观测的解释。

英文摘要:

The extended wings of the Ca II H and K lines provide excellent diagnostics of the temperature stratification of the photosphere of the Sun and of other cool stars, thanks to their LTE opacities and source functions and their large span in formation height. The aim of this study is to calibrate the usage of the H and K wings in one-dimensional interpretation of spatially averaged spectra and in deriving per-pixel stratifications from resolved spectra. I use multi-dimensional simulations of solar convection to synthesize the H and K wings, derive one-dimensional models from these wings as if they were observed, and compare the resulting models to the actual simulation input. I find that spatially-averaged models constructed from the synthesized wings generally match the simulation averages well, except for the deepest layers of the photosphere where large thermal inhomogeneities and Planck-function nonlinearity gives large errors. The larger the inhomogeneity, the larger the latter. The presence of strong network fields increases such inhomogeneity. For quiet photospheric conditions the temperature excesses reach about 200 K. One-dimensional stratification fits of discrete structures such as granulation and small-scale magnetic concentrations give satisfactory results with errors that are primarily due to steep temperature gradients and abrupt changes of temperature with depth. I conclude that stratification modeling using the H and K wings is a useful technique for the interpretation of solar high-resolution observations.

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