November 16th, 2012 by James Ayre
Researchers have discovered a wandering, rogue planet, completely without a sun, for the first time. Such a planet has long been theorized to exist, and there have previously been many possible candidates for one, but this is the first time that one has been confirmed.
It was found by researchers working at the ESO’s Very Large Telescope and the Canada-France-Hawaii Telescope.
ScienceHeathen has more:
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.”
The current theory is that free-floating planets form only one of two ways; as normal planets that are then ejected out of their origin systems, or that they form as they are, simply not having enough mass to become a star.
“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.
They also bring to mind the theory of panspermia, and the possibility that such rogue planets could have had a role in life on the Earth or elsewhere. And also that they could have an impact on the planetary stability of a system, possibly causing the ejection of planets or planetary collisions, based on their gravitational influence.
It’s very possible that such planets are exceptionally common in the universe, perhaps more so than stars. Because they remain mostly invisible to us as a result of lacking light production, there could in fact be rogue planets very near to us without necessarily noticing.
You can read more about that here.
Some background on rogue planets from Wikipedia:
“A rogue planet — also known as an interstellar planet, nomad planet, free-floating planet or orphan planet — is a planetary-mass object which has either been ejected from its system or was never gravitationally bound to any star, brown dwarf or other such object, and that therefore orbits the galaxy directly. Astronomers believe that either way, the definition of planet should depend on current observable state and not origin.”
“In 1998, David J. Stevenson theorized that some planet-sized objects drift in the vast expanses of cold interstellar space and could possibly sustain a thick atmosphere which would not freeze out due to radiative heat loss. He proposes that atmospheres are preserved by the pressure-induced far-infrared radiation opacity of a thick hydrogen-containing atmosphere.”
“It is thought that during planetary system formation, several small protoplanetary bodies may be ejected from the forming system. With the reduced ultraviolet light associated with its increasing distance from the parent star, the planet’s predominantly hydrogen- and helium-containing atmosphere would be easily confined even by an Earth-sized body’s gravity.”
“It is calculated that for an Earth-sized object at a kilobar hydrogen atmospheric pressures in which a convective gas adiabat has formed, geothermal energy from residual core radioisotope decay will be sufficient to heat the surface to temperatures above the melting point of water. Thus, it is proposed that interstellar planetary bodies with extensive liquid water oceans may exist. It is further suggested that these planets are likely to remain geologically active for long periods, providing a geodynamo-created protective magnetosphere and possible sea floor volcanism which could provide an energy source for life. The author admits these bodies will be difficult to detect due to the intrinsically weak thermal microwave radiation emissions emanating from the lower reaches of the atmosphere, although later research suggests that reflected solar radiation and far-IR thermal emissions may be detected if one were to pass within 1000 AU of Earth.”
Source: European Southern Observatory
Image Credits: NAsA/JPL-Caltech; ESO/P. Delorme; ESO/L. Calçada/P. Delorme/R. Saito/VVV Consortium
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