IRIS Movie of the Day
At least once a week a movie of the Sun taken by NASA's Interface Region Imaging Spectrograph (IRIS) is posted by one of the scientists operating the instrument.
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14 Sep 2018
An active region revived
Credit: IRIS, LMSAL/NASA, Gregal Vissers, SU
As solar activity slowly but steadily dwindles to a minimum, one of the observing priorities for IRIS is to track any present active regions during their disk passage. This Mg II k (279.6 nm) slit-jaw movie shows NOAA AR 12719 making its way across the disk, starting three days after the region had emerged. While active at first, the active region seems to be decaying in the first half of the movie, but then magnetic fields suddenly start emerging bringing new life to the scene. The heating that is released while the magnetic fields reconfigure leads to short-lived brightenings, both compact and in more elongated filamentary structures, as the two opposite polarity pores (dark, roundish spots) move apart. Eventually the build up of magnetic potential energy is sufficient to be released in a minor flare visible towards the end of the movie.