XRT Picture of the Week (XPOW)

XRT Picture of the Week (XPOW)

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2012 February 10

Click image for movie. Also available on YouTube

Supra-Arcade Downflows Post X-Flare (2012/01/27)

The uber-active regions 11401 and 11402 continued to fire off flares after our previous feature, the largest of which being an X1.7 flare situated right on the west limb. This provided a phenomenal vantage point on the associated CME, but in a stroke of bad luck, one of XRT's twice-daily synoptic observations fell during the main eruptive phase and caused the ~18 minute gap beginning around 18:00 UT in the attached movie. We did at least get a very neat synoptic composite image out of it! Another interesting feature of this event are the supra-arcade downflows visible after the flare. These features are sunward propogating plasma voids that often appear just above the loop system (referred to as an "arcade") after an eruption in a flaring region. The arrow in the gif animation above points to one of these downflows and much of the general fan structure that develops in the movie may also be the result of downflows clearing the space around them. Supra-arcade downflows were thought to be cross sections of empty flux tubes as they retract from higher up in the corona, but recent research suggests they may be "wakes" (trailing regions of low density) behind much thinner tubes.

Keywords: Downflows, Flare, Post-Flare Loops
Filters: Be_thin

(Prepared by Patrick McCauley)

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