Poynting flux generated by random shuffling of photospheric magnetic footpoints is transferred through the upper atmosphere of the Sun where the plasma is heated to over 1 MK in the corona. High spatiotemporal resolution observations of the lower atmosphere at the base of coronal magnetic loops are crucial to better understand the nature of the footpoint dynamics and the details of magnetic processes that eventually channel energy into the corona. Here, we report high spatial resolution (∼0.″1) and cadence (1.33 s) hyperspectral imaging of the solar Hα line, acquired by the Microlensed Hyperspectral Imager prototype installed at the Swedish 1-m Solar Telescope, that reveal photospheric hot spots at the base of solar coronal loops. These hot spots manifest themselves as Hα wing enhancements, occurring on small spatial scales of ∼0.″2, and timescales of less than 100 s. By assuming that the Hα wings and the continuum form under the local thermodynamic equilibrium condition, we inverted the Hα line profiles and found that the hot spots are compatible with a temperature increase of about 1000 K above the ambient quiet-Sun temperature. The Hα wing integrated Stokes V/I maps indicate that hot spots are related to magnetic patches with field strengths comparable to or even stronger that the surrounding network elements. But they do not show the presence of parasitic polarity magnetic field that would support the interpretation that these hot spots are reconnection-driven Ellerman bombs. Therefore, we interpret these features as proxies of locations where convection-driven magnetic field intensification in the photosphere can lead to energy transfer into higher layers. We suggest that such hot spots at coronal loop footpoints may be indicative of the specific locations and onset of energy flux injection into the upper atmosphere.

中文翻译：

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高光谱成像观测揭示的太阳日冕环脚点处的光层热点


由光球层磁足迹点随机洗牌产生的坡印廷通量通过太阳的上层大气传递，等离子体在日冕中被加热到 1 MK 以上。对日冕磁环底部的低层大气进行高时空分辨率观测对于更好地了解脚点动力学的性质以及最终将能量引导到日冕中的磁过程的细节至关重要。在这里，我们报告了太阳 Hα 线的高空间分辨率 （∼0.“1） 和节奏 （1.33 s） 高光谱成像，该成像由安装在瑞典 1 米太阳望远镜上的微透镜高光谱成像仪原型获得，揭示了太阳日冕环底部的光球热点。这些热点表现为 Hα 翼增强，发生在 ∼0.“2 的小空间尺度上，时间尺度小于 100 秒。通过假设 Hα 翼和连续体在局部热力学平衡条件下形成，我们反转了 Hα 线剖面，发现热点与比环境静日温度高约 1000 K 的温度升高兼容。Hα 翼积分 Stokes V/I 图表明，热点与磁场强度与周围网络单元相当甚至更强的磁斑有关。但它们没有显示寄生极性磁场的存在，而寄生极性磁场可以支持这些热点是重新连接驱动的埃勒曼炸弹的解释。因此，我们将这些特征解释为光球层中对流驱动的磁场增强导致能量转移到更高层的位置的代理。 我们认为，日冕环脚点的这种热点可能表明能量通量注入高层大气的具体位置和开始。