Statistical Study of the Kinetic Features of Supra-arcade Downflows Detected from Multiple Solar Flares
Statistical Study of the Kinetic Features of Supra-arcade Downflows Detected from Multiple Solar Flares
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DOI：
10.3847/1538-4357/ac695d
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发表时间：
2022-06
期刊：
影响因子：
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通讯作者：
Xiaoyan Xie;K. Reeves;Chengcai Shen;Joshua Ingram
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文献类型：
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作者：
Xiaoyan Xie;K. Reeves;Chengcai Shen;Joshua Ingram
我们已经开发了一个跟踪算法来确定超拱廊下行流（SAD）的速度，并建立了一个系统来自动跟踪SAD和测量一些有趣的参数。通过对太阳动力学天文台大气成像组件观测到的六个耀斑进行分析，由于我们观测数据的空间分辨率较高，我们比以前的工作检测到更多更小和更慢的SAD。包含这些事件与较小和较慢的SAD直接导致较低的中值速度和宽度比以前的工作，但拟合的分布和演变的参数仍然显示出良好的一致性与以前的工作。观测到的SAD的宽度、速度和寿命的分布符合对数正态分布，这表明随机和不稳定的过程是太阳爆发期间产生SAD的原因。此外，我们发现，最快的SAD发生在大约中间的高度范围。每个图像中SAD的数量与时间的关系表明，当看到很少SAD时，存在SAD的“休息阶段”。这些发现支持SAD起源于流体不稳定性的观点。我们比较我们的结果与数值模拟，产生SAD的瑞利-泰勒不稳定性和里希特迈尔-梅什科夫不稳定性的混合物，并发现模拟产生的数量与我们的观测结果是一致的。
We have developed a tracking algorithm to determine the speeds of supra-arcade downflows (SADs) and set up a system to automatically track SADs and measure some interesting parameters. By conducting an analysis of six flares observed by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory, we detect more smaller and slower SADs than prior work, due to the higher spatial resolution of our observational data. The inclusion of these events with smaller and slower SADs directly results in lower median velocities and widths than in prior work, but the fitted distributions and evolutions of the parameters still show good consistency with prior work. The observed distributions of the widths, speeds, and lifetimes of SADs are consistent with log-normal distributions, indicating that random and unstable processes are responsible for generating SADs during solar eruptions. Also, we find that the fastest SADs occur at approximately the middle of the height ranges. The number of SADs in each image versus time shows that there are “rest phases” of SADs, when few SADs are seen. These findings support the idea that SADs originate from a fluid instability. We compare our results with a numerical simulation that generates SADs using a mixture of the Rayleigh–Taylor instability and the Richtmyer–Meshkov instability, and find that the simulation generates quantities that are consistent with our observational results.