Planet With No Sun Discovered By Astronomers For First Time Ever
Astronomers have discovered a planet without a sun, marking the first time a free-floating planet has ever been observed. The planet, which goes by the catchy name PSO J318.5-22, is 80 light years from Earth and six times as big as Jupiter. And while such free-floating bodies have been observed before, it's never been clear whether they're brown dwarfs -- failed stars -- or actual planets. This time, researchers say, they think they've really found a planet with no sun.
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"We have never before seen an object free-floating in space that that looks like this. It has all the characteristics of young planets found around other stars, but it is drifting out there all alone," said lead researcher Michael Liu of the Institute for Astronomy at the University of Hawaii at Manoa. "I had often wondered if such solitary objects exist, and now we know they do."
The young planet is 12 million years old and was discovered by the Pan-STARRS 1 telescope on Maui, Hawaii. Liu and his team were scanning the sky for brown dwarfs when they came upon the star-less planet. Brown dwarfs appear as faint, red objects in the sky, but something was different about this brown dwarf: it was one of reddest ones ever observed. The researchers observed the object for two years, and found that the infrared signature of the object was closer to a planet's than to a brown dwarf's. The object is also far smaller than a brown dwarf would be, making it more planet-like.
Eugene Magnier of the University of Hawaii, a coauthor of the study, said that the planet may still be considered a brown dwarf because the line between brown dwarfs and planets is not precisely defined. Magnier also said that his team will continue searching within the orbit of the planet to see if they can find any other celestial objects.
"Most objects in the universe don't form all by themselves. They are in binary or multiple systems," Magnier told the Los Angeles Times. "It is reasonably likely that it has a companion."
A study on the sun-free planet will be published in Astrophysical Journal Letters.
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