Scientists have reported the detection of strong gamma-ray flares from the Crab Nebula, a shattered remnant of a massive star that ended its life in a supernova explosion.

The team found two short-duration gamma-ray pulses coming from the Crab Nebula, which was previously believed to emit radiation that was essentially stable. The pulses were fueled by the most energetic particles ever traced to a discrete astronomical object.

The discovery challenges current theories about the way cosmic particles are accelerated.

We were dumbfounded, said Roger Blandford, who directs the Kavli Institute for Particle Astrophysics and Cosmology, jointly located at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University. It's an emblematic object, he said.

Nearly a thousand years old, the supernova was noted in the constellation of Taurus by Chinese astronomers in the year 1054 AD. The nebula is also referred to as Messier 1 or M1, being the first astronomical object catalogued in 1771 by Charles Messier.

After shedding much of its outer gases and dust, the dying star collapsed into a pulsar, a super-dense, rapidly spinning ball of neutrons. The Crab Nebula's pulsar emits a pulse of radiation every 33 milliseconds, like clockwork.

Though it's only 10 miles across, the amount of energy the pulsar releases is enormous, lighting up the Crab Nebula until it shines 75,000 times more brightly than the sun. Most of this energy is contained in a particle wind of energetic electrons and positrons traveling close to the speed of light.

It's a big deal historically and we're making an amazing discovery about it, said Blandford.