NASA Fermi Detects High Energy Gamma-Rays from Exploding Novae

Using the Fermi satellite, astronomers have spotted high energy gamma rays shooting from an exploding star. The new findings actually overturn the long-held theory that classical nova explosions are not powerful enough to create this high-energy radiation.

In March 2010, researchers using the Large Area Telescope (LAT) onboard NASA's Fermi Gamma-ray Space Telescope satellite detected what appeared to be gamma rays coming from the nova, V407 Cyg. This nova was a sudden, short-lived increase in the brightness of a star and resulted from a runaway thermonuclear explosion. This explosion was the equivalent of about 100,000 times the energy that the sun gives off every year. Unlike supernovas, though, novae don't result in the destruction of their stars.

In this case, the nova was created by the white dwarf star V407 Cyg, which lies about 9,000 light-years away in the plane of our Milky Way galaxy. It possesses a companion star, a pulsating giant red star, which emits a strong stellar wind.

Yet while novae create bright events, scientists once believed that they couldn't be a source for high energy gamma rays. This latest finding, though, contradicts that particular idea.

"This was a completely unexpected discovery and we still don't understand the cause," said Starrfield, computational astrophysicist, in a news release. "No one suspected novae were violent enough to be emitting at these very high energies. However, it now seems possible that a significant fraction-near 100 percent-of novae are gamma ray sources."

The findings reveal a bit more about novae and show that supernovas aren't the only ones that can emit this type of energy.

"This exciting discovery is telling us something important about the explosions of classical novae but we don't, as yet, know what it means," said Starrfield.

The findings are published in the journal Science.