Astronomers from the U.S., U.K., and Australia have discovered a gargantuan planet that boasts the widest orbit of any planet found around a star.
Dubbed 2MASS J2126, the gaseous planet orbits about 1 trillion km from its star, or about 7,000 times the distance between the Earth and the sun.
The researchers published their work in Monthly Notices of the Royal Astronomical Society. The researchers are from the Univ. of Hertfordshire, NASA Ames Research Center, Max Planck Institute for Astronomy, and Australian National Univ.
At first, astronomers believed 2MASS J2126 was a lonely planet, a free floating celestial body with no star to call home. In 2014, 2MASS J2126 was identified as a potential member of the Tucana Horologium Association, a group of stars and brown dwarfs around 45 million years old.
However, nearby—in the same patch of sky—a star called TYC 9486-927-1 existed solely, having never been assigned to a group of young stars.
The researchers discovered that TYC 9486-927-1 and 2MASS J2126 moved through space together, and were each located around 104 light-years from the sun.
Though the research team couldn’t group the binary system with a group of young stars, they used the star’s spectrum to measure its age. The measurement is based on lithium, which is destroyed very early in a star’s life, thus correlating to age. The more lithium present, the younger the star is. The astronomers believe TYC 9486-927-1 is between 10 and 45 million years old.
Finding the age allowed the team to find 2MASS J2126’s mass, which is between 11.6 and 15 times greater than Jupiter’s. 2MASS J2126 straddles the boundary between planet and brown dwarf classification.
Due to the enormous distance between the planet and the host star, it takes 2MASS J2126 roughly 900,000 years to complete an orbit.
“How such a wide planetary system forms and survives remains an open question,” said coauthor Simon Murphy, of the Australian National Univ.
