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标题：Energetics of Hi-C EUV brightenings
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作者：Srividya Subramanian ; Vinay L. Kashyap ; Durgesh Tripathi 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2018
卷号：615
DOI：10.1051/0004-6361/201629304
语种：English
出版社：EDP Sciences
摘要：We study the thermal structure and energetics of the point-like extreme ultraviolet (EUV) brightenings within a system of fan loops observed in the active region AR 11520. These brightenings were simultaneously observed on 2012 July 11 by the High-resolution Coronal (Hi-C) imager and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). We identified 27 brightenings by automatically determining intensity enhancements in both Hi-C and AIA 193 Å light curves. The energetics of these brightenings were studied using the Differential Emission Measure (DEM) diagnostics. The DEM weighted temperatures of these transients are in the range logT(K) = 6.2−6.6 with radiative energies ≈1024−25ergs and densities approximately equal to a few times 109cm−3. To the best of our knowledge, these are the smallest brightenings in EUV ever detected. We used these results to determine the mechanism of energy loss in these brightenings. Our analysis reveals that the dominant mechanism of energy loss for all the identified brightenings is conduction rather than radiation.
关键词：Key wordsenSun: atmosphereSun: coronaSun: UV radiationSun: transition regionSun: activity