Post-Flare Half-Loops: What are They?
Abstract
The M1.4 flare of Jan 28, 2011 has a remarkable resemblance to the famous Tsuneta flare of 1992. It was observed with Hinode/XRT, SDO/AIA, and STEREO (A)/EUVI, giving us higher resolution, greater temperature coverage, and stereoscopic views of this iconic structure. The high temperature images reveal a brightening that grows in size to form a tower-like structure at the top of the post-flare arcade. They also show that loops that are successively connected to this tower develop a density increase in one of their legs that can reach 4 times the density value of the other leg, giving the appearance of "half loops". These jumps in density last for an extended period of time. On the other hand, XRT filter ratios suggest that temperature is approximately uniform along the entire loop. XRT filter-ratio density maps corroborate that the brighter legs have higher density than the rest of the loop. The tower is a localized density increase at even higher densities than the brighter side of the loop. This may correspond to a shock at the top of the loops. We use STEREO images to show that the half loop brightening is not a line-of-sight projection effect of the type suggested by Forbes & Acton.
- Publication:
-
SDO-4: Dynamics and Energetics of the Coupled Solar Atmosphere. The Synergy Between State-of-the-Art Observations and Numerical Simulations
- Pub Date:
- March 2012
- Bibcode:
- 2012decs.confE..12G
- Keywords:
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- SDO;
- SDO-4;
- SDO 4;
- SDO Workshop;
- SDO-4/IRIS/Hinode Workshop;
- Solar Dynamic Observatory