An artist's rendition of planet CFBDSIR2149. The planet's faint glow looks blue through an infrared telescope. In visible light the cold planet would actually appear red.
It's cold and young and massive. And they call it the wanderer. Astronomers recently discovered a new planet
, named CFBDSIR2149, that is relatively close to our solar system. It is also the first convincing evidence of an accepted but yet unsubstantiated theory of roaming planets. Astronomers have theorized for the last decade about the presence of wandering planets that do not orbit stars, and they've found a number of objects that could potentially fit the bill. But without the ability to accurately date these objects, scientists couldn't positively identify them as planets. They could just as easily have been failed stars called brown dwarfs. Luckily for astronomers, CFBDSIR2149 has certain qualities that made identification possible. The wandering planet acts as a groupie to the AB Doradus Moving Group---a band of 30 young stars that travels through space together. These stars are all the same age, so astronomers were able to deduce the age of the planet traveling with them. At 50 to 120 million years old, CFBDSIR2149 is still pretty young. For astronomers, another handy quality of the cosmic nomad's starlessness is the resulting lack of light reflected from its atmosphere. This allows astronomers to study the planet's atmosphere in detail using infrared telescopes, something that would not be possible with star-orbiting planets. Finding CFBDSIR2149 and identifying it as a planet was a coup in and of itself, and astronomers believe that observing this wandering planet will also help them better understand its more rooted counterparts.
Image courtesy of L. Calçada, P. Delorme, Nick Risinger, and R. Saito, European Southern Observatory/VVV Consortium
