Scientists may have found 'orphan' planet NOT orbiting a star

Contributed by
Jan 14, 2013, 1:38 PM EST

Though they vary widely in other characteristics, we usually think of planets as having one unifying quality: they're all orbiting a star, right? Well ... apparently not. It seems there could be quite a few "orphan" worlds just floating out in space, and scientists think they just found one really close to Earth.

Using the Canada-France-Hawaii Telescope and the European Southern Observatory's Very Large Telescope in Chile, a team of astronomers led by Philippe Delorme of the Institute of Planetology and Astrophysics of Grenoble in France discovered CFBDSIR2149, an object about 100 light-years from Earth that could be an orphaned planet that isn't tied to a star.

"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," Delorme said.

The object was found floating in a group of young stars known as the AB Doradus moving group, and scientists believe there's a 90 percent probability that CFBDSIR2149 is somehow tied to that group, and formed along with it 50 to 120 million years ago.

If Delorme and his colleagues are right about the object, then it's a gas giant planet with four to seven times the mass of Jupiter and a temperature that averages more than 800 degrees Farenheit. But there's also still a chance that CFBDSIR2149 is a brown dwarf, a gas object larger than most planets but too small to get the fusion reactions going that allow it to actually become a star.

"We need new observations to confirm that this object belongs to the AB Doradus moving group," Delorme said. "With a good distance measurement and a more accurate proper motion, we will be able to increase (or decrease) the probability that it is indeed a planet."

Though it's definitely the closest to Earth that anyone's found so far, CFBDSIR2149 is very probably not the only "orphan" planet out there in the galaxy. In fact, previous studies have suggested there are actual more orphan planets than there are orbiting planets. But according to Delorme, even if that's true, CFBDSIR2149 is unusually large for what scientists usually think of when it comes to orphan planets.

"We now know that such massive planets are rare and that Neptunes or Earth-mass planets are much more common," Delorme said. "We also know that massive objects are more difficult to eject [from solar systems] than light ones. If you follow the rationale, you deduce that ejected exo-Neptunes and ejected exo-Earths should be much more common than objects like CFBDSIR2149."

(Via Huffington Post)

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