A rogue free-floating planet, completely unattached to any star has been found by researchers working at the ESO’s Very Large Telescope and the Canada-France-Hawaii Telescope. This is the first confirmed observation of a planet wandering throughout space without a parent star, though such planets have long been theorized to exist in great quantities throughout the universe.

This is also the closest such free-floating planet candidate yet discovered, at only about 100 light-years away. Because it is somewhat close and there are no bright stars located near it, researchers have actually been able to study its atmosphere in very great detail.

“Free-floating planets are planetary-mass objects that roam through space without any ties to a star. Possible examples of such objects have been found before, but without knowing their ages, it was not possible for astronomers to know whether they were really planets or brown dwarfs — ‘failed’ stars that lack the bulk to trigger the reactions that make stars shine.”

But the new object, currently named CFBDSIR2149, has changed that. The planet seems to be emerging from a nearby stream of young stars called the AB Doradus Moving Group.

The AB Doradus Moving Group is the nearest known group of this type, its stars move through space in tandem and are theorized to have formed near the same time. Since the planet is likely associated with this group — and therefore also likely young — it becomes possible to infer a lot about it. This includes its mass, temperature, and its atmospheric composition. There is still a small chance though that the association with the moving group is because of a common origin.

This is the first time that an isolated planetary mass object has ever been observed in a moving group.

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

It’s currently thought that free-floating objects such as CFBDSIR2149 are formed either as normal planets and are then ejected out of their star systems, or “as lone objects like the smallest stars or brown dwarfs.”

“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 Philippe Delorme. “If this little object is a planet that has been ejected from its native system,” it brings to mind the possibility of panspermia, and the possibility of such wandering planets having had an impact on the development of life.

It’s possible that worlds such as this could be very common, perhaps as or more common than stars. And simply remaining invisible to us because the don’t give off light, there could potentially be some located very close to us that we have just not observed yet.

“If CFBDSIR2149 is not associated with the AB Doradus Moving Group it is trickier to be sure of its nature and properties, and it may instead be characterised as a small brown dwarf. Both scenarios represent important questions about how planets and stars form and behave.”

“Further work should confirm CFBDSIR2149 as a free-floating planet,” concludes Philippe 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.”

Source: European Southern Observatory

Image Credits: ESO/P. Delorme.; ESO/L. Calçada/P. Delorme/R. Saito/VVV Consortium