Inference of chromospheric plasma parameters on the Sun
Inference of chromospheric plasma parameters on the Sun
复制标题
太阳色球等离子体参数的推断
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Kyuhyoun Cho
中科院分区：
文献类型：
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作者：
J. Chae;M. Madjarska;Hannah Kwak;Kyuhyoun Cho
通过强吸收线可以很好地观测到太阳色球层。我们推断的色球等离子体的物理参数，从这些线使用多层光谱反演。这是一种新的光谱反演技术。我们假定大气层是由有限层数组成的。在每一层中，吸收轮廓是恒定的，并且源函数以恒定的梯度随光学深度而变化。具体来说，我们考虑了一个三层模型的辐射传输，其中最低层是确定与光球和两个上层确定与色球。光球层中的吸收轮廓由Voigt函数描述，色球层中的轮廓由高斯函数描述。这个三层模型由13个参数完全指定。四个参数可以固定为规定值，一个参数可以通过分析卫星光球线来确定。其余8个参数是从约束最小二乘拟合确定的。本文对古德太阳望远镜（GST）快速成像太阳光谱仪（菲斯）在宁静区拍摄的H α和Ca Ⅱ 854.21 nm谱线的光谱数据进行了多层光谱反演。我们发现，我们的模型成功地适合大多数观察到的配置文件，并产生定期的模型参数的地图。这两条线的多普勒宽度推断的组合产生合理的估计的温度和非热的速度在色球层。我们的结论是，我们的多层反演是有用的，以推断色球等离子体参数的太阳。
The solar chromosphere can be observed well through strong absorption lines. We infer the physical parameters of chromospheric plasmas from these lines using a multilayer spectral inversion. This is a new technique of spectral inversion. We assume that the atmosphere consists of a finite number of layers. In each layer the absorption profile is constant and the source function varies with optical depth with a constant gradient. Specifically, we consider a three-layer model of radiative transfer where the lowest layer is identified with the photosphere and the two upper layers are identified with the chromosphere. The absorption profile in the photosphere is described by a Voigt function, and the profile in the chromosphere by a Gaussian function. This three-layer model is fully specified by 13 parameters. Four parameters can be fixed to prescribed values, and one parameter can be determined from the analysis of a satellite photospheric line. The remaining 8 parameters are determined from a constrained least-squares fitting. We applied the multilayer spectral inversion to the spectral data of the H$alpha$ and the Ca II 854.21 nm lines taken in a quiet region by the Fast Imaging Solar Spectrograph (FISS) of the Goode Solar Telescope (GST). We find that our model successfully fits most of the observed profiles and produces regular maps of the model parameters. The combination of the inferred Doppler widths of the two lines yields reasonable estimates of temperature and nonthermal speed in the chromosphere. We conclude that our multilayer inversion is useful to infer chromospheric plasma parameters on the Sun.