Planet with no star found
Thursday 15 Nov 2012 2:25 p.m.
Artist's rendition of CFBDSIR2149-0403
By Dan Satherley
Researchers have spotted a planet hurtling through space without a parent star.
The gas giant, between four and seven times the size of Jupiter, is the first of its kind to be discovered beyond any doubt.
Normally exoplanets are found by analysing a star's wobble caused by its planets' gravitational pull, and the light they block when they pass in front of the star. Without a star to orbit however, CFBDSIR2149-0403 was difficult to find.
"Although theorists had established the existence of this type of very cold and young planet, one had never been observed until today," says Université de Montréal astrophysicist Étienne Artigau.
"The absence of a shining star in the vicinity of this planet enabled the team to study its atmosphere in great detail. This information will in turn enable astronomers to better understand exoplanets that do orbit stars."
Using the Canada France Hawaii Telescope on Hawaii's Mauna Kea and the Very Large Telescope in Chile, the team observed "hundreds of millions" of stars, but only found one planet that wasn't a part of a solar system.
It's not entirely on its own, however – it appears to be travelling with a group of around 30 stars called the "AB Doradus moving group", about 130 light years from Earth.
Astronomers don't know how it came to be – whether it was a failed star, or ejected from a solar system or something else.
"If this little object is a planet that has been ejected from its native system, it conjures up the striking image of orphaned worlds, drifting in the emptiness of space," says Philippe Delorme of the Institute of Planetology and Astrophysics of Grenoble.
Previous objects found alone in space may have been planets, but the lack of evidence meant scientists couldn't confirm they weren't instead brown dwarf stars instead. CFBDSIR2149-0403 is the first scientists are sure is indeed a planet, and not a star.