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Meet the starless planet that floats alone
Just 130 light-years away from Earth is a curiously independent world at least four times bigger than Jupiter
An artist's impression of the free-floating planet CFBDSIRJ2149, which reflects little light because it doesn't orbit a star.
An artist's impression of the free-floating planet CFBDSIRJ2149, which reflects little light because it doesn't orbit a star.
ESO/L. Calçada/P. Delorme/Nick Risinger (skysurvey.org)/R. Saito/VVV Consortium
S

ay hello to what may just be the loneliest planet in the universe. CFBDSIR2149 — as researchers unromantically refer to this orphan world — doesn't have a traditional solar system to call its own, and instead floats through the galaxy untethered to a larger sun-like body. According to a new report in the journal Astronomy and Astrophysics, its existence is making astrophysicists rethink what they knew about starless planets, which may be more common than previously believed. Here's what you should know about this parent-less object:

What's the planet like?
It's titanic — about four to seven times as massive as Jupiter. The free-floating object "cruises unbound through space relatively close to Earth" at roughly 130 light-years away, says Mike Wall at Space.com. Astronomers caught their first glimpse of CFBDSIR2149 ("2149" for short) while hunting for distant brown dwarf stars, or "failed stars" that never quite become massive enough to kick-start thermonuclear reactions at their cores. It's estimated that the lonely 2149 is between 50 and 120 million years old with a surface temperature of 752 degrees Fahrenheit (relatively cool compared to real stars). What's more: It may be like a lost child following a group of unfamiliar companions.

What does that mean? 
The object was pinpointed moving through space among a small group of young stars called the AB Doradus Moving Group star cluster, says Irene Klotz at Discovery News. 2149 stood out among these stars because of its relatively cool temperature. Although it isn't orbiting any of them, there's a 90 percent probability that the oddball planet is "indeed associated with the group," says Space.com's Wall, since all the stars appear to be roughly the same age as it. There's still a small chance that 2149 is an unusually small brown dwarf star, but that means it would have to be billions of years older than its present company. That's why astronomers are pretty sure it's a young planet and not an old, failed star.

How did it end up orphaned?
Scientists aren't sure. Either it formed away from a parent star or was booted out from its original system by gravitational forces. For example, 2149 may have formed originally as part of a solar system, says Michael D. Lemonick at TIME, before it was "sling-shotted out in a close encounter with another planet." 

Are there many others like it?
Not at all. A few orphan worlds were discovered in star-forming regions in the constellation Orion, but "this is the first time we have found one outside the cocoon of star-forming regions in the field," says astrophysicist Étienne Artigau at the University of Montreal, who co-discovered the planet. Now scientists are hoping to study the relatively close anomaly more intently — astronomers have already detected the signature of methane and water vapor in 2149's atmosphere. A separate study from 2011 found that if floating planets do in fact support life, they may act as "stepping stones" to spread life around the galaxy.

Sources: Discovery News, New Scientist, Space.com, TIME

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