Friday, September 24, 2010

'Cannibal' star that swallows planets is spotted by Nasa

'Cannibal' star that swallows planets is spotted by Nasa
By Niall Firth
15th September 2010

A ‘cannibal’ star that has devoured a smaller star or a giant planet has been spotted by astronomers.

The star, known as BP Piscium (BP Psc), is around 1000 light years away and appears to be a more evolved version of our Sun, but it is surrounded by a dusty disk of gas.

Its existence, after it was spotted using NASA's Chandra X-ray Observatory, provides astronomers with new insight into how stars and the planets around them may interact as they age.

A pair of jets several light years long blasting out of the system in opposite directions has also been seen.

While the disk and jets are characteristics of a very young star, several clues - including the new results from Chandra - suggest that BP Psc is not what it originally appeared to be.

Instead, astronomers have suggested that BP Psc is an old star in its so-called red giant phase and the disk and jets are remnants of a nearby star or planet that was destroyed.

When stars like the Sun begin to run of nuclear fuel, they expand and shed their outer layers. Our Sun, for example, is expected to swell so that it nearly reaches or possibly engulfs Earth, as it becomes a red giant star.

'It appears that BP Psc represents a star-eat-star Universe, or maybe a star-eat-planet one,' said Joel Kastner of the Rochester Institute of Technology, who led the Chandra study. 'Either way, it just shows it's not always friendly out there.'

The fact that BP Psc is not located near any star-forming cloud, and there are no other known young stars in its immediate vicinity led scientists to believe that it was not what it initially seemed

Its atmosphere also contains very little lithium, like most older stars.

Planets nearby will have been devastated when BP Psc turned into a giant star. But researchers believe that a second round of planet formation might be occurring in the surrounding disk, hundreds of millions of years after the first round.

'BP Psc shows us that stars like our Sun may live quietly for billions of years,' said co-author David Rodriguez from UCLA, 'but when they go, they just might take a star or planet or two with them.'

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