domingo, 23 de janeiro de 2011

Energy Bubbles discovered at Galaxy's heart

John Roach
for National Geographic News
Published November 10, 2010
Two huge bubbles that emit gamma rays have been found billowing from the center of the Milky Way galaxy, astronomers have announced.
The previously unseen structures, detected by NASA's Fermi Gamma-ray Space Telescope, extend 25,000 light-years north and south from the galactic core.
"We think we know a lot about our own galaxy," Princeton University astrophysicist David Spergel, who was not involved in the discovery, said during a press briefing Tuesday. But "what we see here are these enormous structures … [that] suggest the presence of an enormous energetic event in the center of our galaxy."
For now the source of all that energy is unclear, said study co-author Doug Finkbeiner, an associate professor of astronomy at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
Gamma rays are the most energetic forms of light, and in space they tend to come from violent events such as supernovae or from extreme objects such as black holes and neutron stars. (See "Gamma-Ray Telescope Finds First 'Invisible' Pulsar.")
The newfound bubbles, meanwhile, are made of hot, charged gas that's releasing the same amount of energy as a hundred thousand exploding stars.
"So you have to ask, where could energy like that come from" in the Milky Way? Finkbeiner said.

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