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Artist interpretation of giant flare on EV Lac
Credit:R. Osten et al.; Casey Reed/NASA


What did EV Lac?

Young stars spin fast, and fast rotation powers strong internal dynamos which generate powerful magnetic fields. Because some parts of the star rotate faster than others, the magnetic field lines can become tangled. And when things get too tangled, they get explosive. Tangled magnetic fields on the sun produce strong solar flares, firing high energy particles outward through interplanetary space, doing some real damage to robots and humans who happen to be outside the protection of the earth's magnetosphere. As stars go, the Sun is not particularly active, befitting its rather slow rotation rate (revolving as it does once per month). But young stars can rotate once every few days, so you might expect them to generate more powerful flares. And you'd be right. Recently astronomers discovered the record-breaker, a flare from a star which was brighter than any other flare ever observed. The flare star is EV Lac, a relatively small, common red dwarf star, but at only a few hundred million years old, it's a particularly young, unruly one. The flare from EV Lac was detected by the X-ray Telescope on the Swift satellite and was thousands of times more powerful than the average solar flare, and it lasted for eight hours to boot. The brightness of the flare with time as seen by Swift is shown above left, while an artist rendering of the flare from EV Lac, along with hot plasma trapped within the enhanced magnetic loops which certainly thread its surface, is shown above right. Young stars like EV Lac may have young solar systems around them - what would such powerful flares do to a young earth orbiting this star?


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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:27:17 EDT