It is always amusing to watch newevidence mess up old assumptions. Thereis a lot out there and we get more data with every passing day. The problem is that we can not ever test our theoriesproperly to confirm out ideas.
The only thing we know for sureis that if we could, we would be astounded by how much we never imagined. Thus I find assured commentary to bedisconcerting.
I suspect that there are now patternsout there to be winkled out and explained quite differently from presentparadigms.
Mysterious ‘superflares’ confound astronomers
By Tushna Commissariat
Most of us with an interest in astronomy would recognize the CrabNebula in images and videos quite readily. The supernova remnant, first seen onEarth in the year 1054, consists of a super-dense neutron star that spins about30 times an second, making it a pulsar that swings a beam of radiation towardsEarth, like a lighthouse.
NASA’s Fermi Gamma-ray Space Telescope is one of many that look forhigh-energy radiation sources, and recently the Crab Nebula has caught its eye.The past seven months have seen some rather dramatic variations within thenebula, with Fermi and other telescopes noticing X-ray flares a hundred timesbrighter than seen ever before.
Since 2009 Fermi has detected several short-lived gamma-ray flares atenergies greater than 100 million electron volts (eV), which is much higherthan the flares seen before. On 12 April Fermi detected a flare that grew about30 times more energetic than the nebula’s normal gamma-ray output and aboutfive times more powerful than previous outbursts. On 16 April an even brighterflare erupted, which lasted for a few days before the activity died out.
“These superflares are the most intense outbursts we’ve seen to dateand they are all extremely puzzling events,” says Alice Harding of NASA’s Goddard Space Flight Center
“We think they are caused bysudden rearrangements of the magnetic field not far from the neutron star, butexactly where that’s happening remains a mystery.”
When Fermi noted the variances in 2010 it alerted NASA’s ChandraX-ray Observatory, which began routinely monitoring the nebula to identifyX-ray emissions associated with the outbursts. When Fermi scientists alertedthe astronomers at Chandra about the spike in April, a pre-planned set ofobservations using the observatory was initiated.
Unfortunately, no clear evidence was seen for correlated flares in theChandra images, so the reason for the sudden extreme variations is still amystery. Theorists have deduced that the flares must arise within aboutone-third of a light-year from the neutron star, but efforts to locate themmore precisely have been unsuccessful.
Scientists believe the flares occur as the intense magnetic field nearthe pulsar undergoes sudden structural changes. Such changes can accelerateelectrons to velocities near the speed of light. As these relativisticelectrons interact with the magnetic field, they emit gamma rays. To accountfor the observed emission, scientists say the electrons must have energies 100times greater than can be achieved in any particle accelerator on Earth. Thismakes them the highest energy electrons associated with any source within ourgalaxy.
Take a look at the wonderful video by NASA that shows thechanges as seen by Chandra, as well as some spectacular shots of the nebula.
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