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arXiv · 1402.2457

Sparkling EUV bright dots observed with Hi-C

S. Regnier·C. E. Alexander·R. W. Walsh·A. R. Winebarger·J. Cirtain·L. Golub·K. E. Korreck·N. Mitchell·S. Platt·M. Weber·B. De Pontieu·A. Title·K. Kobayashi·S. Kuzin·C. E. DeForest
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Abstract

Observing the Sun at high time and spatial scales is a step towards understanding the finest and fundamental scales of heating events in the solar corona. The Hi-C instrument has provided the highest spatial and temporal resolution images of the solar corona in the EUV wavelength range to date. Hi-C observed an active region on 11 July 2012, which exhibits several interesting features in the EUV line at 193Å: one of them is the existence of short, small brightenings ``sparkling" at the edge of the active region; we call these EUV Bright Dots (EBDs). Individual EBDs have a characteristic duration of 25s with a characteristic length of 680 km. These brightenings are not fully resolved by the SDO/AIA instrument at the same wavelength, however, they can be identified with respect to the Hi-C location of the EBDs. In addition, EBDs are seen in other chromospheric/coronal channels of SDO/AIA suggesting a temperature between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time series, we define four different categories of EBDs: single peak, double peak, long duration, and bursty EBDs. Based on a potential field extrapolation from an SDO/HMI magnetogram, the EBDs appear at the footpoints of large-scale trans-equatorial coronal loops. The Hi-C observations provide the first evidence of small-scale EUV heating events at the base of these coronal loops, which have a free magnetic energy of the order of 10$^{26}$ erg.

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S. Regnier, C. E. Alexander, R. W. Walsh, A. R. Winebarger, J. Cirtain, L. Golub, K. E. Korreck, N. Mitchell, S. Platt, M. Weber, B. De Pontieu, A. Title, K. Kobayashi, S. Kuzin, C. E. DeForest. 2014-02-11. Sparkling EUV bright dots observed with Hi-C. https://doi.org/10.1088/0004-637x%2F784%2F2%2F134

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