用日全食光谱探测太阳中低层大气对局部热动平衡的偏离
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作者单位:

1.中国科学院大学天文与空间科学学院北京100049;2.中国科学院云南天文台昆明650011)

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P182;

基金项目:

国家自然科学基金项目(11078005、U1931206)资助


Detection of Departure from Thermal Dynamic Equilibrium in the Solar Middle Lower Atmosphere Using Total Solar Eclipse Data
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Affiliation:

1. School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049;2. Yunnan Astronomical Observatory, Chinese Academy of Sciences, Kunming 650011;

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    摘要:

    在太阳大气不同层次连续光谱中叠加有丰富的发射线或吸收线, 对这些谱线轮廓进行反演分析可以探测太阳大气的化学成分和物理状态. 太阳大气的色球及过渡区由于其密度低难以建立热动平衡, 建立相应的大气模型需要采用非局部热动平衡(Non-Local Thermodynamic Equilibrium, N-LTE)理论. 根据相对偏离因子计算来研究太阳中低层大气偏离局部热动平衡(Local Thermodynamic Equilibrium, LTE)分布的情况. 首先对日全食观测过程中得到色球和过渡区不同高度形成的两条光谱数据进行反演, 得到确定观测谱线的参数信息, 如连续谱源函数、谱线源函数、多普勒宽度和由此推出的等效动力学温度; 根据这些反演出的谱线参量计算出二维视场内每个空间采样点偏离LTE状态的定量结果; 其次, 根据用于观测的积分视场单元光纤排布阵列重构出辐射强度、等效动力学温度和相对偏离因子二维分布. 结果显示: 在局部小区域, 温度分布和相对偏离因子的分布存在较强相关性, 而与辐射强度分布无明显相关. 从两条谱线导出的等效温度和相对偏离因子分布存在明显的差异. 这两种二维分布揭示出太阳大气某些小尺度区域具有较强的结构性和复杂性, 为进一步理解太阳中低层大气物理提供了一种新的视角.

    Abstract:

    There are abundant emission and absorption lines superimposed on the continuum spectrum of the solar atmosphere at different levels. The chemical composition and physical state of the solar atmosphere can be probed by the inversion of the profiles of the measured spectral lines. Due to its low density and large temperature difference, it is hard to establish thermal dynamic equilibrium in the chromosphere and transition regions of the Sun. In this paper, the departure from thermodynamic equilibrium in the middle lower atmosphere of the sun is investigated according to the well-defined relative departure factor and the corresponding calculation. We invert the spectral lines formed from chromosphere and transition regions at different heights during a total solar eclipse observation to obtain the line parameters, such as continuum source function, line source function, Doppler width and thus the equivalent kinetic temperature, and then the relative departure factor is calculated. Then, we reconstruct the two-dimensional distribution maps of radiative intensity, equivalent kinetic temperature and relative departure factor according to the alignment of optical fiber array of the integrated field unit (IFU) used by telescope. The results show that there is a certain correlation between the distribution of temperature and relative departure factor, but no evident correlation with the distribution of radiation intensity. The spatial distributions of both effective temperature and departure from thermal equilibrium of the two lines have very different patterns, showing complicated structures. This provides a new perspective for us to further understand the physics of the middle lower atmosphere of the Sun.

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刘曦,屈中权,宋智明.用日全食光谱探测太阳中低层大气对局部热动平衡的偏离[J].天文学报,2021,(1):96-109.

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  • 收稿日期:2020-07-10
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  • 在线发布日期: 2021-02-01
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