Miniature loops in the solar corona
Miniature loops in the solar corona
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日冕中的微型环
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
S. Savage
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文献类型：
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作者：
Krzysztof Barczynski;H. Peter;S. Savage
充满热等离子体的磁环是日冕的主要组成部分。通常，它们的长度约为日冕气压标度高度，即 50 毫米。此前有人提出存在微型版本的热循环。它们的长度只有 1 毫米，几乎没有从色球层突出，并且只跨越光球层中的一个颗粒。这种短环在过渡区温度（0.1 MK）下很好地建立，我们研究了这种微型环是否也存在于日冕温度（> 1 MK）下。我们使用高分辨率日冕成像仪 (Hi-C) 进行极紫外成像 (EUV) 观测，空间分辨率达到前所未有的 0.3 英寸至 0.4 英寸。结合来自太阳动力学天文台 (SDO) 的 EUV 成像和磁图数据以及来自 Hinode 的 X 射线望远镜 (XRT) 数据，我们研究了靠近活动区域的浅滩区域上方的日冕中小环状结构的空间、时间和热演化，并将其与活动区域内的苔藓区域进行了比较。我们发现环状特征的大小、运动和时间演化与光球运动一致，表明与光球磁场密切相关。对齐的磁力图显示，它们的端点之一植根于磁集中。结合 X 射线观测结果显示，它们的热结构与苔藓状特征存在显着差异。考虑到不同的情况，这些特征很可能是热环的微型版本，植根于小型新兴磁环（或通量管）中颗粒相对两侧的磁集中。
Magnetic loops filled with hot plasma are the main building blocks of the solar corona. Usually they have lengths of the order of the barometric scale height in the corona that is 50 Mm. Previously it has been suggested that miniature versions of hot loops exist. These would have lengths of only 1 Mm barely protruding from the chromosphere and spanning across just one granule in the photosphere. Such short loops are well established at transition region temperatures (0.1 MK), and we investigate if such miniature loops also exist at coronal temperatures (>1 MK). We used extreme UV imaging (EUV) observations from the High-resolution Coronal Imager (Hi-C) at an unprecedented spatial resolution of 0.3" to 0.4". Together with EUV imaging and magnetogram data from the Solar Dynamics Observatory (SDO) and X-Ray Telescope (XRT) data from Hinode we investigated the spatial, temporal and thermal evolution of small loop-like structures in the solar corona above a plage region close to an active region and compared this to a moss area within the active region. We find that the size, motion and temporal evolution of the loop-like features are consistent with photospheric motions, suggesting a close connection to the photospheric magnetic field. Aligned magnetograms show that one of their endpoints is rooted at a magnetic concentration. Their thermal structure, as revealed together with the X-ray observations, shows significant differences to moss-like features. Considering different scenarios, these features are most probably miniature versions of hot loops rooted at magnetic concentrations at opposite sides of a granule in small emerging magnetic loops (or flux tubes).