Astronomers Discover Lonely Planet Without a Star

First Posted: Oct 10, 2013 03:58 AM EDT

A team of international astronomers have discovered an exotic young planet in our Milky Way galaxy that is eighty light years away from the Earth and was formed merely 12 million years ago.

Astronomers have discovered a strange free-floating planet dubbed PSO J318.5-22 that is 80 light years away from the Earth and has a mass that is six times more than Jupiter.The star hosts no stars. It came into existence some 12 million years ago, which is like a newborn in planet lifetime. The astronomers identified the strange lonely planet from its faint and exclusive heat signature as it didn't match the objects surrounding it. It was identified with the help of a survey telescope Pan-STARRS1 (PS1) that is located on Haleakala, Maui.

This is not the first time that astronomers have spotted such free floating objects. But it was unclear till date whether these free floating objects were failed stars or orphaned planets. But this finding confirms that they are indeed planets. The light coming from PSO J318.5-22 is nearly 100 billion times fainter in optical wavelengths compared to the planet Venus. Most of the planet's energy is emitted in infrared wavelengths, NBCNews reports.

The first alien world beyond our solar system was discovered in 1992 more than 1,000 light years away from Earth. According to the scientists, one in six stars hosts an Earth sized planet.

"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," team leader Dr. Michael Liu of the Institute for Astronomy at the University of Hawaii, Manoa, said in a press statement. "I had often wondered if such solitary objects exist, and now we know they do."

Astronomers till date have managed to directly image just a handful of planets. This newly discovered lonely planet PSO J318.5-22 is one of the lowest mass free floating object ever recorded perhaps even the lowest. But what remains unique about it is its mass, color and energy output, which is similar to directly imaged planets.

Orphan planets or rogue planets are objects ejected from its system and are never gravitationally bound to any star, brown star or other such objects. During the hunt for failed stars also called as brown dwarfs, astronomers came across PSO J318.5-22. Due to the cool temperatures brown dwarfs are faint and are red in color. On analyzing the data from the PS1 telescope they noticed that PSO J318.5-22 was unique and redder than even the reddest known brown dwarfs.

"Planets found by direct imaging are incredibly hard to study, since they are right next to their much brighter host stars. PSO J318.5-22 is not orbiting a star so it will be much easier for us to study. It is going to provide a wonderful view into the inner workings of gas-giant planets like Jupiter shortly after their birth," said Dr. Niall Deacon of the Max Planck Institute for Astronomy in Germany and a co-author of the study.

On completing the analysis, the team concluded that PSO J318.5-22 belongs to a group of young stars called the Beta Pictoris that is a moving group formed 12 million years ago. Beta Pictoris even has a young gas-giant planet in orbit around it. But PSO J318.5-22 is lower in mass compared to Beta Pictoris planets and was formed in a different manner.

The finding was documented in the Astrophysical Journal Letters.  

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