An international team of astronomers has discovered an exotic young planet that is not orbiting a star. This free-floating planet, named PSO J318.5-22 was found using the Pan-STARRS 1 (PS1) wide-field survey telescope on Haleakala, Maui. It is also unusual in that it is only 12 million years old, an infant in terms of planet age. Just 80 light years away , belonging to the Beta Pictoris group of stars it is in our local neighborhood. It is large, about six times the size of Jupiter. In a University of Hawaii Institute for Astronomy press release issued on October 9, 2013, Liu is quoted: “We have never before seen an object free-floating in space that looks like this. It has all the characteristics of young planets found around other stars, but it is drifting out there all alone.“ Liu continues, “I had often wondered if such solitary objects exist, and now we know they do.”
The planet is extremely cold and faint, about 100 billion times fainter in optical light than the planet Venus. Most of its energy is emitted at infrared wavelengths Thousands of planets have been found by watching the dimming or wobbling of the host star, very few have been seen via direct imaging. “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.
PSO J318.5-22 was discovered during a search for the failed stars known as brown dwarfs. Due to their relatively cool temperatures, brown dwarfs are very faint and have very red colors. To circumvent these difficulties, Liu and his colleagues have been mining the data from the PS1 telescope. PS1 is scanning the sky every night with a camera sensitive enough to detect the faint heat signatures of brown dwarfs. PSO J318.5-22 stood out as an oddball, redder than even the reddest known brown dwarfs.