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Telescopes around the world recorded the brightest explosion ever detected in our galaxy, which sent x-rays and gamma rays careening outward at incredible speeds, astronomers announced on Friday. In just two-tenths of a second, the flare, located 50,000 light-years from Earth in the constellation Sagittarius, shot out as much energy as our sun gives off in 250,000 years.
Scientists detected evidence of the flare, coming from the magnetized neutron star, or magnetar, known as SGR 1806-20 on December 27, 2004. "Astronomically speaking, this explosion happened in our backyard," remarks Bryan Gaensler of the Harvard-Smithsonian Center for Astrophysics who is analyzing radio observations of the event. The initial burst lasted just less than a second, followed by a tail of x-rays lasting six minutes. Radio waves from the flare's aftermath continue to be recorded by telescopes the world over. "It was the mother of all magnetic flares--a true monster," says Kevin Hurley of the University of California at Berkeley. Indeed, some 15 spacecrafts were in the radiation's path as it streamed through our solar system and many had their onboard instruments knocked off-scale as a result.
Material ejected by the blast sped outward at speeds close to one third the speed of light. "We can see the structure of the flare's aftermath and we can watch it change from day to day," Gaensler notes. "That combination is completely unprecedented." In addition, it was 100 times brighter than similar events detected from magnetars in the past. There are four so-called Soft Gamma Repeaters (SGR) magnetars, which release gamma ray flashes periodically, but the latest event was so powerful that scientists think it may represent a new class of SGRs. "We know of only two other giant flares in the past 35 years and this December event was 100 times more powerful," says David Palmer of Los Alamos National Laboratory. Astronomers hope to better understand the magnetar phenomenon with the help of the Swift spacecraft, which was launched in November 2004, and should spot more magnetars from other galaxies. Researchers from a number of institutions presented the new work Friday at NASA headquarters in Washington, D.C. and papers describing the findings have been submitted to the journal Nature.
