Abstract

Two-dimensional spectra of the Sun (from the center to the limb of the disk) in wavelength ranges of λ = 532.0–532.8 and 539.1–539.9 nm were registered with the ATsU-5 telescope (the Russian abbreviation ATsU corresponds to the Astronomical Coelostat Mounting) of the Main Astronomical Observatory of the National Academy of Sciences of Ukraine (MAO NASU) after replacing the regular main mirror by a short-focus one (with a focal length of 1 m). An advantage of the applied method is that the spectrum is registered simultaneously for different heliocentric positions on the solar disk. The observational data were reduced for the influence of light scattered in the spectrograph, the atmospheric-stray light, the spectrograph instrumental profile, and some aberrations. The center-to-limb ratios of the spectra are compared to the data available in the literature. The data on variations in the profiles of eleven spectral lines in transition from the center to the limb of the solar disk were obtained. The revealed nonmonotonicity of these changes is explained by inhomogeneities in physical conditions on the surface of the Sun. In general, the depths of the studied Fe I lines demonstrate the decreasing tendency in the strength of lines when passing toward the limb. For most lines, the full widths at half maximum increase toward the disk edge. The equivalent widths show differently directed variations. The parameters of the line Mn I λ 539.4 nm behave in a different way: all three analyzed parameters grow toward the disk edge; however, at the extreme limb, the depth and the equivalent width also start to decrease. The limb-effect of lines was measured; it exhibits the highest value when the core positions in weak lines are compared. For strong lines, the limb-effect is strongest while comparing the middle parts of the line bisectors.

中文翻译：

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弗劳恩霍夫线在太阳圆盘中心到四边的过渡中

摘要

用ATsU-5望远镜记录了波长范围为λ= 532.0–532.8和539.1–539.9 nm的太阳的二维光谱（从圆盘的中心到盘的四肢）（俄文缩写ATsU对应于天文学的定速镜乌克兰国家科学院主要天文台（MAO NASU）的安装），然后将常规主镜替换为短焦距镜（焦距为1 m）。该应用方法的优点是，光谱同时针对太阳盘上不同的日心位置记录。由于光谱仪中散射的光，大气杂散光，光谱仪的仪器轮廓和一些像差的影响，减少了观测数据。将光谱的中心-边缘比率与文献中可用的数据进行比较。获得了关于从太阳圆盘的中心到四肢过渡的十一条光谱线的轮廓变化的数据。这些变化所揭示的非单调性是由太阳表面物理条件的不均匀性所解释的。通常，研究的Fe I线的深度表明，当线穿过肢体时，线的强度会降低。对于大多数行，最大宽度的一半朝着磁盘边缘增加。等效宽度显示不同方向的变化。Mn Iλ539.4 nm线的参数以不同的方式运行：所有三个分析的参数都朝着磁盘边缘增长；然而，在极端肢体处，深度和等效宽度也开始减小。测量线的肢体效应；比较弱线的核心位置时，它显示出最大值。对于强线，在比较线平分线的中间部分时，肢体效应最强。