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

  • Released Wednesday, May 11, 2011
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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.

For more Crab Nebula media go to #10708.

There are strange goings-on in the Crab Nebula. On April 12, 2011, NASA's Fermi Gamma-ray Space Telescope detected the most powerful in a series of gamma-ray flares occurring somewhere within the supernova remnant.

Watch this video on the NASAexplorer YouTube channel.

For complete transcript, click here.

Scientists hoped that NASA's Chandra X-ray Observatory would locate X-ray sources correlated to the gamma-ray flares seen by Fermi and Italy's AGILE satellites. Two observations were made during the April 2011 superflare, but there's no clear evidence of them in the Chandra images.

Credit: NASA/CXC/MSFC/M.Weisskopf and A. Tennant.

Video of Crab flare sequence.

Credit: NASA/DOE/Fermi LAT/R. Buehler

Fermi's LAT discovered a gamma-ray 'superflare' from the Crab Nebula on April 12, 2011. These images show the number of gamma rays with energies greater than 100 million electron volts from a region of the sky centered on the Crab Nebula. Both views eliminate emission form the Crab pulsar by showing the sky in between its pulses. In both images, the bright source below is the Geminga pulsar. At left, the region 20 days before the flare; at right, April 14. Credit: NASA/DOE/Fermi LAT/R. Buehler

Fermi's LAT discovered a gamma-ray 'superflare' from the Crab Nebula on April 12, 2011. These images show the number of gamma rays with energies greater than 100 million electron volts from a region of the sky centered on the Crab Nebula. Both views eliminate emission form the Crab pulsar by showing the sky in between its pulses. In both images, the bright source below is the Geminga pulsar. At left, the region 20 days before the flare; at right, April 14.

Credit: NASA/DOE/Fermi LAT/R. Buehler

Fermi's LAT discovered a gamma-ray 'superflare' from the Crab Nebula on April 12, 2011. These images show the number of gamma rays with energies greater than 100 million electron volts from a region of the sky centered on the Crab Nebula. Both views eliminate emission form the Crab pulsar by showing the sky in between its pulses. In both images, the bright source below is the Geminga pulsar. At left, the region 20 days before the flare; at right, April 14. No Labels.Credit: NASA/DOE/Fermi LAT/R. Buehler

Fermi's LAT discovered a gamma-ray 'superflare' from the Crab Nebula on April 12, 2011. These images show the number of gamma rays with energies greater than 100 million electron volts from a region of the sky centered on the Crab Nebula. Both views eliminate emission form the Crab pulsar by showing the sky in between its pulses. In both images, the bright source below is the Geminga pulsar. At left, the region 20 days before the flare; at right, April 14. No Labels.

Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 1.Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 1.

Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 2.Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 2.

Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 3.Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 3.

Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 4.Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 4.

Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 5.Credit: NASA/DOE/Fermi LAT/R. Buehler

April Flare Frame 5.

Credit: NASA/DOE/Fermi LAT/R. Buehler

For More Information

See http://www.nasa.gov/mission_pages/GLAST/news/crab-flare.html

Credits

Please give credit for this item to:
NASA/Goddard Space Flight Center. However, each image should be credited as indicated above.

This page was originally published on Wednesday, May 11, 2011.
This page was last updated on Wednesday, May 3, 2023 at 1:53 PM EDT.

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