2D non-LTE modelling of a filament observed in the Hα line with the DST/IBIS spectropolarimeter
2D non-LTE modelling of a filament observed in the Hα line with the DST/IBIS spectropolarimeter
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DOI：
10.1051/0004-6361/201935358
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发表时间：
2019-10
影响因子：
6.5
通讯作者：
P. Schwartz;S. Gunár;J. Jenkins;D. Long;P. Heinzel;D. O. P. Sciences;S. Republic;A. Institute;T. U. O. Sciences;Czech Republic;Ucl Mullard Space Science Laboratory;H. Mary;Surrey;UK.;D. PhysicsAstronomy;California State Polytechnic University;Ca;Usa
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作者：
P. Schwartz;S. Gunár;J. Jenkins;D. Long;P. Heinzel;D. O. P. Sciences;S. Republic;A. Institute;T. U. O. Sciences;Czech Republic;Ucl Mullard Space Science Laboratory;H. Mary;Surrey;UK.;D. PhysicsAstronomy;California State Polytechnic University;Ca;Usa
上下文。我们用安装在邓恩太阳望远镜上的干涉二维光谱偏振仪(IBIS)研究了2017年5月29日观测到的一个大的静止灯丝的碎片。我们把重点放在它喷发前的静止阶段。目标。我们分析了在H-α谱线上获得的光谱观测结果，从而得出了观测到的细丝碎片的等离子体的热力学性质。方法：研究方法。我们使用了一个2D灯丝模型，在偏离局部热力学平衡的条件下，使用了辐射传输计算。我们采用了一种正演模拟技术，我们使用2D模型来生成合成的Hα线轮廓，并将其与观测结果进行比较。然后我们找到了一组模型输入参数，它产生了与观测结果最符合的合成光谱。结果。我们的分析表明，观察到的细丝碎片的一部分比另一部分更热、密度更低、更静止，更冷、更密集、更动态。第一部分的衍生温度为6000K~10000K，第二部分的衍生温度为11000K~14000K，第一部分的气体压力为0.2~0.4dyn cm−2，后部分的气体压力约为0.15dyn cm−2。前者的视线速度绝对值为6~7公里S−1，微湍流速度绝对值为8~9公里S−1；后者视线速度绝对值为0~2.5公里S−1，微湍流速度绝对值4~6公里S−1。
Context. We study a fragment of a large quiescent filament observed on May 29, 2017 by the Interferometric BIdimensional Spectropolarimeter (IBIS) mounted at the Dunn Solar Telescope. We focus on its quiescent stage prior to its eruption. Aims. We analyse the spectral observations obtained in the Hα line to derive the thermodynamic properties of the plasma of the observed fragment of the filament. Methods. We used a 2D filament model employing radiative transfer computations under conditions that depart from the local thermodynamic equilibrium. We employed a forward modelling technique in which we used the 2D model to produce synthetic Hα line profiles that we compared with the observations. We then found the set of model input parameters, which produces synthetic spectra with the best agreement with observations. Results. Our analysis shows that one part of the observed fragment of the filament is cooler, denser, and more dynamic than its other part that is hotter, less dense, and more quiescent. The derived temperatures in the first part range from 6000 K to 10 000 K and in the latter part from 11 000 K to 14 000 K. The gas pressure is 0.2–0.4 dyn cm−2 in the first part and around 0.15 dyn cm−2 in the latter part. The more dynamic nature of the first part is characterised by the line-of-sight velocities with absolute values of 6–7 km s−1 and microturbulent velocities of 8–9 km s−1. On the other hand, the latter part exhibits line-of-sight velocities with absolute values 0–2.5 km s−1 and microturbulent velocities of 4–6 km s−1.