Not lost in space: Astronomers spot potential rogue planet


A team of astronomers conducting the Canada-France Brown Dwarfs Survey (CFBDS) have published a study stating that they have discovered what they believe is an immense rogue planet, several times the size of Jupiter. Further to that, it is the closest of its kind that we know of, located just 100 light years away.

"Looking for planets around their stars is akin to studying a firefly sitting one centimetre away from a distant, powerful car headlight," says study lead author Philippe Delorme, who is from Institut de planétologie et d'astrophysique de Grenoble, CNRS/Université Joseph Fourier, France, according to Science Daily. "This nearby free-floating object offered the opportunity to study the firefly in detail without the dazzling lights of the car messing everything up."

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The planet, designated CFBDSIR J214947.2-040308.9 (or CFBDSIR2149 to its friends), was discovered during observations with the Canada-France-Hawaii Telescope on Mauna Kea in Hawaii. The team, which included 4 members from the Université de Montréal, found the potential planet while searching for 'brown dwarfs' — sometimes referred to as 'sub-stellar objects' or 'substars' — which are essentially stars that tried to form, but ultimately failed (either failing to achieving stellar fusion, or only achieving it for a very short time). The smallest brown dwarf discovered yet is roughly 8 times the mass of Jupiter (with an upper limit of nearly 80 Jupiter masses), so with CFBDSIR2149 coming up smaller than that, the team investigated the possibility that it was, instead, a rogue planet.

Further examination of CFBDSIR2149 was made by the Very Large Telescope, at the European Southern Observatory on Cerro Paranal in northern Chile, which gathered more information about its mass, composition and atmosphere.

CFBDSIR2149 is estimated to be four to seven times the size of Jupiter, and was discovered not by the light reflected from a star (as most planets are found via direct observation), but instead from the infrared glow it emits from its core. Based on the information gathered, the team concluded that there is a high probability that it is a young, free-roaming planet, rather than a brown dwarf. Since it is moving along with a group of young stars that has been named the 'AB Doradus moving group' — a cluster of about 30 stars that are moving through space with the star AB Doradus — it is possible that CFBDSIR2149 formed around one of the stars in the group, however its movement along with them could also simply be a coincidence.

"These objects are important, as they can either help us understand more about how planets may be ejected from planetary systems, or how very light objects can arise from the star formation process," says Delorme. "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."

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"To me," added Delorme, according to Cosmos Magazine, "the best thing is that this object is a really easy-to-study prototype of the 'normal' giant planets we hope to discover and study with the upcoming generation of direct imaging instruments."