August 26th 12, 03:19 PM
posted to sci.physics,sci.astro
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Surprising New Neutrino Halo Mechanism discovered in Supernova Explosions
Halo of neutrinos alters physics of exploding stars
http://www.spacedaily.com/reports/Ha...ar s_999.html
As these stars run out of fuel, their cores suddenly collapse to form a neutron star, which quickly rebounds sending seas of neutrinos through the surrounding stellar envelope and out into space.
Even as the collapsed core is rebounding, the rest of the star is still falling inward. Plumes of matter sink, accreting onto the core. "This matter is actually causing some small fraction of neutrinos to bounce at wide angles and cross the trajectories of neutrinos coming from the core," Cherry said.
Astrophysicists knew that the heart of that envelope contained these scattered neutrinos, but because they are relatively few compared with the numbers streaming from the core, they thought their influence on the physics of these explosions would be so minor it could be ignored. Not so, Cherry and colleagues demonstrated in a paper they published in Physics Review Letters. They showed that neutrinos streaming from the core interacted with halo neutrinos far more often than anticipated.
Cherry calculated how often that might occur and how large a difference it would make to their models of neutrinos within supernovae. "What was so startling about this is that nowhere was the correction less than 14 percent. That's enough that you need to worry about it," he said. Indeed, the some places in the outer regions of the envelope require as much as a 10 fold correction.
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