Universe  ID: 10767

NASA's Fermi Spots 'Superflares' in the Crab Nebula

The famous Crab Nebula supernova remnant has erupted in an enormous flare five times more powerful than any previously seen from the object. The outburst was first detected by NASA's Fermi Gamma-ray Space Telescope on April 12 and lasted six days.

The nebula, which is the wreckage of an exploded star whose light reached Earth in 1054, is one of the most studied objects in the sky. At the heart of an expanding gas cloud lies what's left of the original star's core, a superdense neutron star that spins 30 times a second. With each rotation, the star swings intense beams of radiation toward Earth, creating the pulsed emission characteristic of spinning neutron stars (also known as pulsars).

Apart from these pulses, astrophysicists regarded the Crab Nebula to be a virtually constant source of high-energy radiation. But in January, scientists associated with several orbiting observatories — including NASA's Fermi, Swift and Rossi X-ray Timing Explorer — reported long-term brightness changes at X-ray energies.

Scientists think that the flares occur as the intense magnetic field near the pulsar undergoes sudden restructuring. Such changes can accelerate particles like electrons to velocities near the speed of light. As these high-speed electrons interact with the magnetic field, they emit gamma rays in a process known as synchrotron emission.

To account for the observed emission, scientists say that the electrons must have energies 100 times greater than can be achieved in any particle accelerator on Earth. This makes them the highest-energy electrons known to be associated with any cosmic source.

Based on the rise and fall of gamma rays during the April outbursts, scientists estimate that the size of the emitting region must be comparable in size to the solar system. If circular, the region must be smaller than roughly twice Pluto's average distance from the sun.

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Walt Feimer (HTSI): Animator
Scott Wiessinger (UMBC): Animator
Chris Smith (HTSI): Animator
Scott Wiessinger (UMBC): Video Editor
Scott Wiessinger (UMBC): Narrator
Scott Wiessinger (UMBC): Producer
Francis Reddy (SPSYS): Writer
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G2011-049 -- Crab Nebula Flare

SVS >> Gamma Ray
SVS >> Neutron Star
SVS >> Satellite
SVS >> Pulsar
SVS >> Edited Feature
SVS >> Gamma Ray Observatory
SVS >> Fermi
DLESE >> Narrated
SVS >> Supernova
SVS >> Star
SVS >> Nebula
NASA Science >> Universe