Astronomers Identify Orphan Exoplanet Close to Our Solar System

Artist’s impression of newly identified free-floating planet labeled CFBDSIR2149 located only about 100 light years from Earth. (Image: ESO/L. Calçada/P. Delorme/Nick Risinger-skysurvey.org/R. Saito/VVV Consortium)

An international team of astronomers using the European Southern Observatory’s Very Large Telescope (VLT) and the Canada-France-Hawaii Telescope has identified what they’re calling the most exciting free-floating, or rogue planet ever found.

Writing in the journal Astronomy & Astrophysics, the scientists say this rogue planet, located relatively close to our own Solar System – about only 100 light years from Earth — may help explain how planets and stars form.

A free-floating planet is one that has no gravitational ties to any particular star or other stellar object so it wanders alone in space. Also called orphan or nomad planets, these objects are believed to have been ejected from their original home solar system at some time in the distant past.

While objects such as this have been found before, scientists haven’t been too clear on whether or not they were true planets or if they were, perhaps, brown dwarfs, which are stars that failed to fully form and are unable to generate or sustain the needed nuclear fusion to become true stars.

Since this newly identified rogue planet doesn’t have a very bright star close to it, the astronomers say that they were able to study it and its atmosphere in great detail.

Appearing as a faint blue dot near the center of photo, this image of the free-floating planet CFBDSIR2149 was captured in infrared light on ESO’s New Technology Telescope in Chile. (Image: ESO/P. Delorme)

“Looking for planets around their stars is akin to studying a firefly sitting one centimeter away from a distant, powerful car headlight,” says Philippe Delorme from the Institut de planétologie et d’astrophysique de Grenoble, lead author of the study that identified the new planetary object. “This nearby free-floating object offered the opportunity to study the firefly in detail without the dazzling lights of the car messing everything up.”

Astronomers say that this newly discovered object, called CFBDSIR2149, seems to be traveling along with a group of young stars that may have all formed at the same time called the AB Doradus Moving Group.  This group of about 30 or so stars is also moving through space with the star AB Doradus, the primary star within a three star system found in the constellation Dorado.

The scientists say that this planetary object is the first that was ever identified within a moving group of stars.  And, if they find that it’s actually linked with the AB Doradus Moving Group, it, like the stars in the group, would be a relatively young object.

A real association between this nomad planet with the moving star group, according to the astronomers, could make it easier for them to figure out the object’s age, temperature, mass and atmospheric composition.

But the scientists say there’s also a small chance that the planet’s relationship with the moving star group might be by chance.

If it’s found that the planetary object isn’t actually associated with the group, the astronomers say that it would be trickier to track down its nature and physical properties.

“Further work should confirm CFBDSIR2149 as a free-floating planet,” says Delorme. “This object could be used as a benchmark for understanding the physics of any similar exoplanets that are discovered by future special high-contrast imaging systems, including the SPHERE instrument that will be installed on the VLT.”