Major flares observed by XRT. Click the image to watch the movie of the event or
click here to watch the youtube version
AR13500: Starting off the Holiday Season with a Pop
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In the last week of November, the Sun sent a sudden celebration of flares and aurora to Earth during the start of the holiday season. On November 23rd, an energetic active region, AR13500, rotated onto the solar disk. The activity and complexity of the sunspot prompted the Max Millennium group, a collection of solar scientists, to place a ‘Major Flare Watch’ on the area. However, as the spot continued to move across the disk, activity died down and the complexity reduced. Until November 28th when the quiet sunspot erupted with a powerful M9.8 class flare, almost an X-class (the most powerful class), after the end of the watch period, despite the decay of the sunspot complexity. Sunspot complexity is closely watched as scientists can estimate the likelihood of a moderate to major flare using the magnetic field configuration. The Hale/Mt. Wilson Observatory class is one of the classifications commonly used (different designations found here). In this case, AR13500 was designated beta-gamma-delta; taking that designation apart, the spot has touching, opposite magnetic fields with a shape that decays rapidly. This leads to a process called magnetic reconnection which emits a massive amount of energy in the form of a flare. The AR then died down to a beta-gamma region a day before the eruption. Losing the delta complexity seemed to have little effect on the punch this region could send to Earth. Not only did AR13500 erupt powerfully, but also threw solar material towards Earth in a Coronal Mass Ejection (CME). The CME arrived on December 1st with an aurora display seen as far south as North Dakota. This CME induced a class 3 geomagnetic storm, a strong storm. Geomagnetic storms have the ability to affect power lines on Earth and satellite performance in orbit. Fortunately, this past storm did not impact operations in the sky nor on the ground. The accompanying video was taken by Hinode XRT, which was observing the active region when the M9.8 class flare erupted. This video was taken using the Al-poly filter highlighting the flare loops. Note that the video becomes saturated when the flare erupts, which is seen around 20:00 UT on November the 28th, due to the brightness of the flare. The title image is a before and after the M9.8 flare, look at the change. An incredible catch of a powerful flare from XRT. Keywords: AR Tracking, Flare Filters: Al-Poly |
(Prepared by Rhiannon Fleming and Aki Takeda)
The XRT instrument team is comprised of SAO, NASA, JAXA, and NAOJ.
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