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arXiv 1712.09255astro-ph.SR
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THEMIS观测的静止日珥He Ⅰ D3谱线的光谱特征

Spectral Characteristics of the He I D3 Line in a Quiescent Prominence Observed by THEMIS

J. Koza, J. Rybák, P. Gömöry, M. Kozák, A. López Ariste

摘要:

我们分析了一个静态日珥的观测望远镜Heliographique pour l 'Etude du Magnetisme et des Instabilites Solaires(THEMIS)在He I 5876 A(He I D3)多重峰,旨在测量He I D3轮廓的光谱特性,并为他们找到一个适当的拟合模型。用双高斯近似拟合系统测量了He I D3 Stokes I剖面的组分特性。该模型产生He I D3组分峰强度比为$5.5\pm0.4$,其不同于光学薄极限中预期的值8。大多数测得的多普勒速度位于$\pm5$ km/s区间内,在峰值0.4 km/s附近的标准偏差为$\pm1.7$ km/s。半峰全宽的宽分布对于He I D3蓝色分量在0.25 A和0.30 A处具有两个最大值,对于红色分量在0.22 A和0.31 A处具有两个最大值。组分的宽度比为$1.04\pm0.18$。我们表明,双高斯模型系统地低估了蓝翼强度。为了解决这个问题,我们调用了一个双温度多高斯模型,由两个双高斯,它提供了一个更好的表示,是免费的机翼强度赤字的He I D3。该模型认为目标日珥的冷、热分量的温度分别为11.5 kK和91 kK。典型的He ID 3分布的冷分量和热分量具有6.6和8的分量峰强度比,这意味着冷分量的突出几何宽度为17 μ m,光学厚度为0.3,而热分量的光学厚度可以忽略不计。这些突出的参数似乎是现实的,这表明物理充分的多高斯模型解释He I D3分光偏振由当前的反演代码具有重要意义。

英文摘要:

We analyze the observations of a quiescent prominence acquired by the Telescope Heliographique pour l'Etude du Magnetisme et des Instabilites Solaires (THEMIS) in the He I 5876 A (He I D3) multiplet aiming to measure the spectral characteristics of the He I D3 profiles and to find for them an adequate fitting model. The component characteristics of the He I D3 Stokes I profiles are measured by the fitting system approximating them with a double Gaussian. This model yields an He I D3 component peak intensity ratio of $5.5\pm0.4$, which differs from the value of 8 expected in the optically thin limit. Most of the measured Doppler velocities lie in the interval $\pm5$ km/s, with a standard deviation of $\pm1.7$ km/s around the peak value of 0.4 km/s. The wide distribution of the full-width at half maximum has two maxima at 0.25 A and 0.30 A for the He I D3 blue component and two maxima at 0.22 A and 0.31 A for the red component. The width ratio of the components is $1.04\pm0.18$. We show that the double-Gaussian model systematically underestimates the blue wing intensities. To solve this problem, we invoke a two-temperature multi-Gaussian model, consisting of two double-Gaussians, which provides a better representation of He I D3 that is free of the wing intensity deficit. This model suggests temperatures of 11.5 kK and 91 kK, respectively, for the cool and the hot component of the target prominence. The cool and hot components of a typical He I D3 profile have component peak intensity ratios of 6.6 and 8, implying a prominence geometrical width of 17 Mm and an optical thickness of 0.3 for the cool component, while the optical thickness of the hot component is negligible. These prominence parameters seem to be realistic, suggesting the physical adequacy of the multi-Gaussian model with important implications for interpreting He I D3 spectropolarimetry by current inversion codes.

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