The researchers ran simulations of the orbit of the new object, in an attempt to understand how it would be affected by the hypothetical Planet X. They found that a mysterious planet of the kind previously suggested — a huge Super-Earth on a very wide orbit — fit with the way that their new find was moving through the solar system.
The newly discovered object is called 2015 TG387, is probably a small dwarf planet at just 300km across, and is incredibly far away. It is currently lying about two and a half times further away from the Sun than Pluto is.
It often reaches much further away. Its orbit takes it to about 2,300 AU — that is 2,300 times as far away from the sun as we are, and vastly more than the already huge 34 AU that the distant Pluto sits at.
At that distance, 2015 TG387 is one of the few known objects that is so far away that its orbit is not affected by even the giant planets in our solar system like Neptune and Jupiter.
Carnegie’s Scott Sheppard and his colleagues — Northern Arizona University’s Chad Trujillo, and the University of Hawaii’s David Tholen — are once again redefining our Solar System’s edge. They discovered a new extremely distant object far beyond Pluto with an orbit that supports the presence of an even-farther-out, Super-Earth or larger Planet X.
The newly found object, called 2015 TG387, will be announced Tuesday by the International Astronomical Union’s Minor Planet Center. A paper with the full details of the discovery has also been submitted to the Astronomical Journal.
The object was discovered as part of the team’s ongoing hunt for unknown dwarf planets and Planet X. It is the largest and deepest survey ever conducted for distant Solar System objects.
“These distant objects are like breadcrumbs leading us to Planet X. The more of them we can find, the better we can understand the outer Solar System and the possible planet that we think is shaping their orbits — a discovery that would redefine our knowledge of the Solar System’s evolution,” Sheppard added.
It took the team a few years of observations to obtain a good orbit for 2015 TG387 because it moves so slowly and has such a long orbital period. They first observed 2015 TG387 in October of 2015 at the Japanese Subaru 8-meter telescope located atop Mauna Kea in Hawaii. Follow-up observations at the Magellan telescope at Carnegie’s Las Campanas Observatory in Chile and the Discovery Channel Telescope in Arizona were obtained in 2015, 2016, 2017 and 2018 to determine 2015 TG387’s orbit.
2015 TG387 is likely on the small end of being a dwarf planet since it has a diameter near 300 kilometers. The location in the sky where 2015 TG387 reaches perihelion is similar to 2012 VP113, Sedna, and most other known extremely distant trans-Neptunian objects, suggesting that something is pushing them into similar types of orbits.
h/t Digital mix guy