宁静太阳临边外色球的高阶帕申发射线
High-order Paschen emission from the quiet-Sun off-limb chromosphere
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中文总结 AI 辅助
本研究借助Sunrise III搭载的SCIP探测到宁静太阳临边外色球的高阶氢帕申线，发现其特性与Ca II 854.2 nm线存在差异，结合非LTE辐射转移模拟揭示其可作为光学薄等离子体的新诊断工具。
中文摘要 AI 辅助
我们利用Sunrise III气球望远镜搭载的色球红外光谱偏振仪（SCIP），在宁静太阳临边外色球中探测到了高阶氢帕申发射线（Pa 15、Pa 16和Pa 17）。这些谱线呈现类似针状体的纤维状结构，且多普勒速度系统地小于Ca II 854.2 nm谱线，表明它们光学厚度更小，更易受视线方向平均效应影响，尤其在临边附近。采用球对称一维代码rhsphere进行的非局部热动平衡（Non-LTE）辐射转移合成，再现了整体光谱特性。观测到的三条帕申线的比值与合成及理论结果存在系统偏差，提示可能存在额外物理效应影响高阶帕申线的形成。本研究证明了高阶帕申线作为临边外色球中光学薄等离子体新诊断工具的潜力。
英文摘要
We report the detection of high-order hydrogen Paschen emission lines (Pa~15, Pa~16, and Pa~17) in the quiet-Sun chromosphere off the solar limb using the Chromospheric Infrared SpectroPolarimeter (SCIP) on board the {\sc Sunrise~iii} balloon telescope. These lines reveal thread-like structures resembling spicules and exhibit systematically smaller Doppler velocities than Ca~II~854.2~nm, suggesting that they are optically thinner and more affected by line-of-sight averaging, especially near the limb. Non-LTE radiative transfer synthesis using the spherically symmetric one-dimensional code \texttt{rhsphere} reproduces the overall spectral properties. The observed ratios among three Paschen lines show systematic deviations from synthetic and theoretical results, suggesting that additional physical effects may influence the formation of high-order Paschen lines. The study demonstrates the potential of high-order Paschen lines as a new diagnostic of optically thin plasma in the off-limb chromosphere.
