SPECTROSCOPIC SIGNATURES RELATED TO A SUNQUAKE
SPECTROSCOPIC SIGNATURES RELATED TO A SUNQUAKE
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与日震相关的光谱特征
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
L. Green
中科院分区：
文献类型：
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作者：
S. Matthews;L. Harra;S. Zharkov;L. Green
耀斑相关的声发射（日震（SQs））的存在下，在一些耀斑，只有在特定的位置在耀斑环境中，是一个严峻的挑战，我们目前的理解耀斑能量传输过程。为了有助于理解SQs的起源，我们提出了一个新的光谱观测的比较，从日出的EUV成像光谱仪（EIS）和界面区域成像光谱仪（IRIS）的色球层，过渡区和日冕以上的SQ，并将它们与光谱中观察到的一部分的耀斑区域没有声学签名。使用时间距离和声学全息方法来确定SQ的证据，我们发现，与许多以前的SQ检测不同，信号相当分散，但是时间距离和6和7 MHz的源会聚在相同的空间位置。我们还看到了一些证据，表明在不同的频率下有不同的进化，7 mHz的峰值比6 mHz的峰值早。使用EIS和IRIS光谱测量，我们发现在这个位置，在7 mHz峰值时，光谱发射明显更强烈，显示出比没有SQ的位置更大的速度位移和更宽的轮廓，并且蓝移，热日冕，硬X射线（HXR）和红移色球发射之间存在良好的相关性，这与非热电子快速加热驱动的强烈向下运动和色球冲击形成的想法一致。利用Mg II三重线的诊断潜力，我们还发现了大气深处单个大温度升高的证据，这与这种情况是一致的。6 mHz和时间-距离峰值信号的时间与能量释放过程中的第二个峰值重合，但在这种情况下，我们在地震位置没有发现HXR发射的证据，而是发现非常宽的谱线，强烈地向红色移动，表明可能存在向下传播的阿尔文波的显著通量。
The presence of flare-related acoustic emission (sunquakes (SQs)) in some flares, and only in specific locations within the flaring environment, represents a severe challenge to our current understanding of flare energy transport processes. In an attempt to contribute to understanding the origins of SQs we present a comparison of new spectral observations from Hinode’s EUV imaging Spectrometer (EIS) and the Interface Region Imaging Spectrograph (IRIS) of the chromosphere, transition region, and corona above an SQ, and compare them to the spectra observed in a part of the flaring region with no acoustic signature. Evidence for the SQ is determined using both time–distance and acoustic holography methods, and we find that unlike many previous SQ detections, the signal is rather dispersed, but that the time–distance and 6 and 7 mHz sources converge at the same spatial location. We also see some evidence for different evolution at different frequencies, with an earlier peak at 7 mHz than at 6 mHz. Using EIS and IRIS spectroscopic measurements we find that in this location, at the time of the 7 mHz peak the spectral emission is significantly more intense, shows larger velocity shifts and substantially broader profiles than in the location with no SQ, and there is a good correlation between blueshifted, hot coronal, hard X-ray (HXR), and redshifted chromospheric emission, consistent with the idea of a strong downward motion driven by rapid heating by nonthermal electrons and the formation of chromospheric shocks. Exploiting the diagnostic potential of the Mg ii triplet lines, we also find evidence for a single large temperature increase deep in the atmosphere, which is consistent with this scenario. The time of the 6 mHz and time–distance peak signal coincides with a secondary peak in the energy release process, but in this case we find no evidence of HXR emission in the quake location, instead finding very broad spectral lines, strongly shifted to the red, indicating the possible presence of a significant flux of downward propagating Alfvén waves.