Astronomers have detected a planet, which until now was thought to be a free-floating planet, in a huge, lonely orbit around its star. The planet, known as 2MASS J2126, is about 1 trillion kilometers from the star, or about 7000 times the Earth to Sun distance.
First discovered by US astronomers in a sky survey, 2MASS J2126 was initially identified as a young, low mass object, possibly a young star or even a free floating planet. There was no host star or companion detected.
Fast forward to the present, where Dr Niall Deacon from University of Hertfordshire has been spending the last few years looking for wide orbiting planets. As a part of his research, he discovered that the star TYC 9486-927-1 and 2MASS J2126 are moving through space together and are both about 104 light years from the Sun, implying that they are in some way linked.
Until now no one had suggested that TYC 9486-927-1 and the lonely planet were associated.
“This is the widest planet system found so far and both the members of it have been known for eight years,” said Dr Deacon, lead-author of a paper published in the Monthly Notices of the Royal Astronomical Society. “But nobody had made the link between the objects before. The planet is not quite as lonely as we first thought, but it’s certainly in a very long distance relationship.”
To establish the age of the young host star, scientists analyzed its light spectrum looking for signatures of the element lithium. The more lithium detected, the younger it is, since lithium is mostly destroyed early on in a stars life. Researchers found TYC 9486-927-1 has stronger signatures of lithium than a typical 45 million year old star, but weaker signatures than a 10 million year old star, implying an age between the two.
Using this age the team was able to estimate the mass of 2MASS J2126, finding it to be between 11.6 to 15 times the mass of Jupiter.
Subsequently, 2MASS J2126 is now the widest-known orbit of any planet found around another star. At such incredible distances it takes roughly 900,000 years to complete one orbit.