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arXiv 2005.06064astro-ph.SR
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出射通量MHD模式的多温度日冕喷流个例研究

A case-study of multi-temperature coronal jets for emerging flux MHD models

Reetika Joshi, Ramesh Chandra, Brigitte Schmieder, Fernando Moreno-Insertis, Guillaume Aulanier, Daniel Nóbrega-Siverio, Pooja Devi

摘要:

背景:热日冕喷流是太阳大气的一个基本观测特征,其物理起源仍在积极辩论中。目的:我们研究了2017年4月4日在活动区NOAA 12644发生的六个经常性急流。它们在AIA的所有热过滤器中被观察到,并且在IRIS狭缝颚高空间和时间分辨率图像中被观察到。方法:AIA过滤器允许我们使用过滤器比率方法研究射流的温度和排放测量。我们研究了预喷流相位通过分析的强度振荡的基础上的射流与小波技术。结果如下:AIA和IRIS数据的一个很好的共对准表明,射流是在一个冠状,双室结构与冷发射的一侧和热发射在其他的顶部启动。热喷流在高温过滤器中准直,具有高速度(约250 km/s),并伴随着冷浪涌和喷射内核,两者都以约45 km/s的速度移动。在喷流的前阶段,在它们的底部,我们发现与小喷射同相的准周期强度振荡;它们的周期在2到6分钟之间,让人想起声波或MHD波。结论:这一系列的射流和浪涌提供了一个很好的案例研究,以测试二维和三维磁流体动力学(MHD)模型,导致磁通量出现。观测中发现的双室结构对应于包含重联位点的电流片下方的模型中发现的冷环和热环区域。与内核的冷浪涌是可比的冷喷射和等离子体团,自然出现在模型中。

英文摘要:

Context: Hot coronal jets are a basic observed feature of the solar atmosphere whose physical origin is still being actively debated. Aims: We study six recurrent jets occurring in the active region NOAA 12644 on April 04, 2017. They are observed in all the hot filters of AIA as well as cool surges in IRIS slit-jaw high spatial and temporal resolution images. Methods: The AIA filters allow us to study the temperature and the emission measure of the jets using the filter ratio method. We study the pre-jet phases by analyzing the intensity oscillations at the base of the jets with the wavelet technique. Results: A fine co-alignment of the AIA and IRIS data shows that the jets are initiated at the top of a canopy-like, double-chambered structure with cool emission on one side and hot emission in the other. The hot jets are collimated in the hot temperature filters, have high velocities (around 250 km/s) and accompanied by the cool surges and ejected kernels both moving at about 45 km/s. In the pre-phase of the jets, at their base we find quasi-periodic intensity oscillations in phase with small ejections; they have a period between 2 and 6 minutes and are reminiscent of acoustic or MHD waves. Conclusions: This series of jets and surges provides a good case-study to test the 2D and 3D magnetohydrodynamic (MHD) models that result from magnetic flux emergence. The double-chambered structure found in the observations corresponds to the cold and hot loop regions found in the models beneath the current sheet that contains the reconnection site. The cool surge with kernels is comparable with the cool ejection and plasmoids that naturally appear in the models.

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