Rare radio supernova in nearby galaxy is nearest supernova in 5 years

Washington, May 28 (ANI): A rare radio supernova found by astronomers last month has been estimated to be the nearest supernova in five years, which underscores the promise of new, more sensitive radio surveys to find supernovas hidden by gas and dust.

The radio supernova was discovered on April 8 in M82, a small irregular galaxy located nearly 12 million light years from Earth in the M81 galaxy group, by the Very Large Array, a New Mexico facility operated by the National Radio Astronomy Observatory (NRAO).

Bower and his colleagues were studying the motion of M82 with the VLBA, which links the VLA and nine other radio telescopes into a very high resolution instrument, when they noticed a very bright radio source - five times brighter than anything else in the galaxy - in the VLA data.

The team looked at earlier observations and found the same source, but almost twice as bright, in data taken May 3, 2008.

Data from March 24, 2008, showed an even brighter source - 10 times brighter than in April 2009 - while Oct. 29, 2007, data showed no bright radio source.

Extrapolating backward in time, the research team estimates that the star exploded sometime in January 2008, apparently near the very center of the galaxy.

The team rejected alternative explanations for the dimming radio source, such as a flare created by a star falling into a supermassive black hole.

The newly discovered supernova is thus the brightest in radio wavelengths in the past 20 years, according to Bower, and is one of only a few dozen radio supernovas observed to date.

It was subsequently confirmed by NRAO's Very Long Baseline Array (VLBA), a 10-telescope array whose baseline stretches from Hawaii to the Virgin Islands, providing the sharpest vision of any telescope on Earth.

"This supernova is the nearest supernova in five years, yet is completely obscured in optical, ultraviolet and X-rays due to the dense medium of the galaxy," said Geoffrey Bower, assistant professor of astronomy at the University of California, Berkeley.

"This just popped out; in the future, we want to go from discovery of radio supernovas by accident to specifically looking for them," he added. (ANI)