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arXiv 2302.13632astro-ph.SRastro-ph.IM
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HMI盘外耀斑观测综述

An overview of HMI off-disk flare observations

Dennis Fremstad, Juan Camilo Guevara Gómez, Hugh Hudson, Juan Carlos Martínez Oliveros

摘要:

内容:对太阳耀斑的白光连续观测通常有日冕对应物,包括经典的“白光连续”(WLP)现象。目的:日冕发射耀斑,看到白光连续,以前很少报道。我们试图利用现代数据来了解WLP事件的形态。研究方法:我们使用涵盖2011-2017年的新在线目录,确定了由SDO(太阳动力学观测卫星)上的HMI(日光层和磁成像仪)实验检测到的一组14个WLP示例。这些总是伴随着来自低层大气的白光耀斑(WLF),由边缘附近的耀斑发射,正如RHESSI(Rheven Ramaty高能光谱成像仪)的硬X射线图像所识别的那样。HMI提供了完整的斯托克斯信息,我们已经使用线偏振(Q~和~U)来区分冷材料的汤姆逊散射。结果:事件形态大致可分为三类:射血、回线和棘波,但许多事件表现出多种现象。结论:HMI观测到的日冕白光连续体类似于日冕仪的观测,探测到了许多日冕发射和动力学的例子。利用Stokes线偏振,我们估算了14个事件中11个事件的热日冕等离子体质量,发现它们与典型的CME质量相似,但不超过10 $^{15}$ \,g。我们注意到,HMI观测并没有掩盖明亮的太阳盘,也不是为日冕观测而设计的,导致相对较低的信噪比。因此,我们相信,未来这种观测如果得到更好的优化,将取得更大的成果。

英文摘要:

Context: White-light continuum observations of solar flares often have coronal counterparts, including the classical ``white-light prominence'' (WLP) phenomenon. Aims: Coronal emissions by flares, seen in white-light continuum, have only rarely been reported previously. We seek to use modern data to understand the morphology of WLP events. Methods: We have identified a set of 14 examples of WLP detected by the HMI (Heliospheric and Magnetic Imager) experiment on board SDO (the Solar Dynamics Observatory satellite), using a new on-line catalogue covering 2011-2017. These invariably accompanied white-light flares (WLF) emission from the lower atmosphere by flares near the limb, as identified by hard X-ray images from RHESSI (the Reuven Ramaty High Energy Spectroscopic Imager). HMI provides full Stokes information, and we have used the linear polarisations (Q~and~U) to distinguish Thomson scattering from cool material. Results: The event morphologies fit roughly into three categories: Ejection, Loop, and Spike, but many events show multiple phenomena. Conclusions: The coronal white-light continuum, observed by HMI analogously to the observations made by a coronagraph, detects many examples of coronal emission and dynamics. Using the Stokes linear polarisation, we estimate the masses of hot coronal plasma in 11 of the 14 events and find them to be similar to typical CME masses, but not exceeding 10$^{15}$\,g. We note that the HMI observations do not occult the bright solar disk and were not designed for coronal observations, resulting in relatively low signal-to-noise ratios. We therefore believe that future such observations with better optimisation will be even more fruitful.

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