The effect of a solar flare on chromospheric oscillations
The effect of a solar flare on chromospheric oscillations
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太阳耀斑对色球振荡的影响
DOI：
10.1093/mnras/stab642
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发表时间：
2021
影响因子：
4.8
通讯作者：
Millar D
中科院分区：
文献类型：
--
作者：
Millar D
长期以来，无论是在安静的条件下，还是在太阳耀斑期间，都能观察到太阳大气中的振荡。色球以其3分钟的信号而闻名，这种信号在太阳黑子银幕上很强，其周期由色球的声截止频率决定。少数观测表明，色球信号受到太阳耀斑等高能事件的影响，然而耀斑活动和这些振荡之间的联系仍不清楚。在这项工作中，我们提供了在M1耀斑的脉冲阶段发生的太阳黑子上方色球振荡结构变化的证据。使用CRISP仪器在H α和Caii8542 ä谱线上的成像数据，我们采用了一种将模型与功率谱进行拟合的方法，以生成红色噪声背景上存在振荡信号证据的地图。比较耀斑脉冲相前后的结果，我们发现耀斑开始后的振荡信号有两个方面的不同：振荡信号的位置发生了变化，振荡的典型周期有增加的趋势(在某些情况下，从<；100 S增加到∼200 S)。这两个结果都可以通过耀斑活动期间色球中磁场的重组来解释，这一重组得到了日冕环路图像的支持，这些图像显示了磁连接的明显变化。这些结果代表了活跃区域可能受到太阳耀斑影响的多种方式之一。
Oscillations in the solar atmosphere have long been observed both in quiet conditions and during solar flares. The chromosphere is known for its 3-min signals, which are strong over sunspot umbrae, and have periods determined by the chromosphere’s acoustic cut-off frequency. A small number of observations have shown the chromospheric signals to be affected by energetic events such as solar flares, however the link between flare activity and these oscillations remains unclear. In this work, we present evidence of changes to the oscillatory structure of the chromosphere over a sunspot which occurs during the impulsive phase of an M1 flare. Using imaging data from the CRISP instrument across the H α and Caii8542 Å spectral lines, we employed a method of fitting models to power spectra to produce maps of where there is evidence of oscillatory signals above a red-noise background. Comparing results taken before and after the impulsive phase of the flare, we found that the oscillatory signals taken after the start of the flare differ in two ways: the locations of oscillatory signals had changed and the typical periods of the oscillations had tended to increase (in some cases increasing from <100 s to ∼200 s). Both of these results can be explained by a restructuring of the magnetic field in the chromosphere during the flare activity, which is backed up by images of coronal loops showing clear changes to magnetic connectivity. These results represent one of the many ways that active regions can be affected by solar flares.
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影响因子：
4.9
作者：
S. Quinn;A. Reid;M. Mathioudakis;Christoper R Nelson;S. Krishna Prasad;S. Zharkov
通讯作者：
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DOI：
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发表时间：
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DOI：
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发表时间：
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