Nov. 7, 2006 — The most colossal X-ray flare ever detected has been caught in the act of zapping its solar system with planet-killing radiation — not our solar system, thankfully.
The star is II Pegasi in the constellation Pegasus, about 135 light-years from Earth. That means the explosive flare seen by NASA's Swift satellite — a spacecraft designed to detect much more distant and powerful gamma ray bursts — actually took place around the year 1871. Light from the event is only now reaching Earth.
The X-ray flare is the first-ever detected beyond our own sun that bears a striking resemblance to the much smaller "X-class" flares generated occasionally by our own sun.
"It's a hundred thousand times more powerful than the largest solar flares ever recorded," said astronomer Steven Drake of NASA's Goddard Space Flight Center. Despite being far more powerful, it looks like it was created in the same way, he said.
It starts with a tangle of magnetic field lines on the surface of a star that short-circuits. When that happens, atomic particles are accelerated to speeds only seen on Earth in high tech particle accelerators.
The accelerated particles can emit gamma rays, which is what caught the Swift satellite's attention in the first place. When the satellite turned to face II Pegasi, it took aim with its X-ray detector and caught the hour-long eruption of X-rays. The X-rays were created as material violently erupted from the sun and then arched back down and slammed back onto the star's surface.
By comparison, X-ray flares on the sun last only second or minutes, at most.
"It's certainly one of the biggest ever seen," said Drake of the II Pegasi flare. It's the hands-down winner in terms of those seen in "soft" X-rays, which are the rays just beyond the wavelength of extreme ultraviolet light.
