In mid-July, XRT captured this spectacular cusp-shaped arcade
(a collection of nearby magnetic field lines) as NOAA active region
11520
rotated onto the west limb. These features are thought to indicate a
site of ongoing
magnetic reconnection above the cusp, which produces a sunward
plasma flow along the cusp arcade that heats and enhances the loops
such that they emit the soft x-ray emission seen here by XRT. The
extent of the candle flame in the left image is about 167,000 km
beyond the limb or about 13x Earth's diameter. To increase
signal-to-noise, these images are summations of 16 images with ~0.18s
exposure times. Previous XPOWS for similar structures can be found here:
[1] [2]
[3]
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