Astronomers in Hawaii have discovered a new planet that has no star to orbit- the first of its kind ever found.
The wandering planet, dubbed PSO J318.5-22, was first identified by the Pan-STARRS 1 telescope in Haleakala, Maui, and is similar in composition to gas giants that are known to orbit young stars. In this case though, there is no such star present.
“We have never before seen an object that looks like this,” says Dr Michael Liu, leader of the team responsible for the discovery at the University of Hawaii. “It has all the characteristics of young planets found around other stars, but it is drifting out there all alone. I had often wondered if such solitary objects exist, and now we know they do.”
The planet is only 80 light years from Earth – just around the corner in interstellar terms – and was discovered through the use of a technique usually reserved for discovering ‘brown dwarfs’ – failed stars that give off a faint red light that astronomers hunt for in the night sky. PSO J318.5-22 stood out to researchers as it was far redder than any brown dwarf they had previously seen, and further investigation revealed its true nature not as a brown dwarf, but as a lone planet.
The discovery of PSO J318.5-22 may have wider benefits to the astronomic world. “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,” said co-author Dr Niall Deacon of the Max Planck Institute for Astronomy in Germany. “It is going to provide a wonderful view into the inner workings of gas-giant planets like Jupiter shortly after their birth.”