Velocity Structure and Temperature Dependence of an Extreme-Ultraviolet Jet Observed by Hinode
Velocity Structure and Temperature Dependence of an Extreme-Ultraviolet Jet Observed by Hinode
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DOI：
10.1007/s11207-019-1469-8
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发表时间：
2019-04
期刊：
影响因子：
2.8
通讯作者：
T. Kawai;N. Kanda;S. Imada
中科院分区：
文献类型：
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作者：
T. Kawai;N. Kanda;S. Imada
EUV和X射线喷流的加速机制仍然不清楚。一般来说，该机制有两个候选者。一个是磁场重联，另一个是色球蒸发。我们利用太阳动力学天文台/大气成像组件、太阳X射线望远镜、太阳光学望远镜和极紫外成像光谱仪观测到了2011年2月18日10：50 - 11：10 UT之间的一个相对紧凑的X射线喷流。我们的结果如下：i）极紫外和X射线观测显示了X射线喷流的一般特征，例如横跨极性反转线的拱形结构，拱形结构的一条腿上显示的喷流亮点，以及拱形结构上方的尖顶。ii）多波长观测和CaiiH线图像显示存在低温（约10 000 K）等离子体（即，灯丝）在射流的中心。（3）在磁象和CaiiH线象中，暗条存在于极性反转线的上方，弧也跨在极性反转线的上方，另外，在观测到喷流前后几小时，喷流周围出现了磁抵消现象。iv）由多普勒速度图、计算的差分辐射测量和合成谱估计的加速等离子体的温度分布表明，等离子体速度与其温度之间没有明显的依赖关系。对于我们的第三个结果，观测表明磁抵消可能与喷流和暗条的形成有关。这表明喷流的触发是磁抵消而不是磁通出现。第四个结果表明，伴随着X射线喷流的等离子体加速似乎是由磁场重联而不是色球蒸发引起的。
The acceleration mechanism of EUV and X-ray jets is still unclear. In general, there are two candidates for the mechanism. One is magnetic reconnection, and the other is chromospheric evaporation. We observed a relatively compact X-ray jet that occurred between 10:50 – 11:10 UT on 18 February 2011 by using theSolar Dynamics Observatory/Atmospheric Imaging Assembly, and theX-ray Telescope,Solar Optical Telescope, andEUV Imaging SpectrometeronboardHinode. Our results are as follows: i) The EUV and X-ray observations show the general characteristics of X-ray jets, such as an arcade straddling a polarity inversion line, a jet bright point shown at one leg of the arcade, and a spire above the arcade. ii) The multi-wavelength observations and CaiiH line image show the existence of a low-temperature (≈ 10 000 K) plasma (i.e., filament) at the center of the jet. iii) In the magnetogram and CaiiH line image, the filament exists over the polarity inversion line and arcade is also straddling it. In addition, magnetic cancellation occurs around the jet a few hours before and after the jet is observed. iv) The temperature distribution of the accelerated plasma, which was estimated from Doppler velocity maps, the calculated differential emission measure, and synthetic spectra show that there is no clear dependence between the plasma velocity and its temperature. For our third result, observations indicate that magnetic cancellation is probably related to the occurrence of the jet and filament formation. This suggests that the trigger of the jet is magnetic cancellation rather than flux emergence. The fourth result indicates that plasma acceleration accompanied by an X-ray jet seems to be caused by magnetic reconnection rather than chromospheric evaporation.