TIME DEPENDENT NONEQUILIBRIUM IONIZATION OF TRANSITION REGION LINES OBSERVED WITH IRIS
TIME DEPENDENT NONEQUILIBRIUM IONIZATION OF TRANSITION REGION LINES OBSERVED WITH IRIS
复制标题
用 IRIS 观测到的过渡区线的时间依赖性非平衡电离
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
B. Gudiksen
中科院分区：
文献类型：
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作者：
J. Martínez;B. Pontieu;V. Hansteen;B. Gudiksen
本文分析了硅离子和氧离子的非统计平衡电离特性。本文利用界面区成像光谱仪（IRIS）对5个太阳目标（安静太阳、日冕洞、斑块、静止活动区和耀斑区）进行了观测。IRIS最适合这项工作，因为它具有高节奏（高达0.5 s），高空间分辨率(高达0。″32)，以及O iv λ1401和Si iv λ1402的高信噪比。我们发现，硅离子和氧离子三次电离线之间的观测强度比取决于它们的总强度，这种相关性取决于观测到的区域（安静的太阳、日冕洞、斑块或活跃区域）和特定的观测对象（针状体、动态环、喷流、微耀斑或本影）。为了解释观测结果，我们将它们与从太阳大气的二维自一致辐射MHD模拟中获得的合成剖面进行了比较，其中应用了硅和氧的统计平衡或非平衡处理。这些合成观测结果与观测结果显示出模糊相似的相关性，即强度比与其强度之间的相关性，但只有在非平衡情况下，我们才发现（部分）观测结果可以重现。我们得出结论，这些线条是由统计平衡形成的。我们使用我们的时间依赖的非平衡电离模拟来描述这些观察到的性质背后的物理机制。
The properties of nonstatistical equilibrium ionization of silicon and oxygen ions are analyzed in this work. We focus on five solar targets (quiet Sun; coronal hole; plage; quiescent active region, AR; and flaring AR) as observed with the Interface Region Imaging Spectrograph (IRIS). IRIS is best suited for this work owing to the high cadence (up to 0.5 s), high spatial resolution (up to 0.″32), and high signal-to-noise ratios for O iv λ1401 and Si iv λ1402. We find that the observed intensity ratio between lines of three times ionized silicon and oxygen ions depends on their total intensity and that this correlation varies depending on the region observed (quiet Sun, coronal holes, plage, or active regions) and on the specific observational objects present (spicules, dynamic loops, jets, microflares, or umbra). In order to interpret the observations, we compare them with synthetic profiles taken from 2D self-consistent radiative MHD simulations of the solar atmosphere, where the statistical equilibrium or nonequilibrium treatment of silicon and oxygen is applied. These synthetic observations show vaguely similar correlations to those in the observations, i.e., between the intensity ratios and their intensities, but only in the nonequilibrium case do we find that (some of) the observations can be reproduced. We conclude that these lines are formed out of statistical equilibrium. We use our time-dependent nonequilibrium ionization simulations to describe the physical mechanisms behind these observed properties.