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.
A Hot, Hazy Day on the West Limb
Credit: IRIS, LMSAL/NASA, and Dr. Chad Madsen, SAO
Solar flares are the most energetic impulsive events in the Solar System and remain a heavily researched topic in solar astronomy. This video is an example of an M-class flare, the second-most energetic class in the GOES classification system, occurring on the limb of the Sun. Most of the light you see in this video is coming from carbon atoms that have been ionized once at a temperature of about 50,000 degrees C. As energy builds up on the limb, we first see a distinct loop structure emerge from a bright point in the lower half of the field of view. Then, suddenly, the flare goes off, producing a growing bright patch that sprawls along the limb as well as a hook-shaped structure that juts out into space. However, there is another unusual feature here: a cloudy haze that seemingly appears out of nowhere over the limb. This haze is actually light emitted by iron atoms that are ionized not once, not twice, but 20 times at a temperature of nearly 12 million degrees C! The haze appears to develop out of nowhere since much of the super-heated plasma from the flare is invisible to the detector until it has had enough time to ionized iron twenty times, allowing an atomic transition that produces light visible to the detector.