Astronomers Dr Chadwick Trujillo of Gemini Observatory in Hawaii and Dr Scott Sheppard of Carnegie Institution for Science have discovered a dwarf planet, scientifically called 2012 VP113 and nicknamed Biden, beyond the known edge of our Solar System.
Three images of 2012 VP113, each taken about two hours apart, were combined into one. The first image was artificially colored red, second green and third blue. 2012 VP113 moved between each image as seen by the red, green and blue dots. The background stars and galaxies did not move and thus their red, green and blue images combine to show up as white sources. Image credit: Scott Sheppard / Chad Trujillo.
Solar System can be divided into three parts: the rocky planets like Earth, which are close to the Sun; the gas giants; and the frozen objects of the Kuiper belt, which lie just beyond Neptune’s orbit.
Beyond this, there appears to be an edge to the Solar System where only one object, Sedna, was previously known to exist for its entire orbit.
But the newly found dwarf planet has an orbit that stays even beyond Sedna, making it the furthest known in the Solar System.
Sedna was discovered beyond the Kuiper Belt edge in 2003, and it was not known if Sedna was unique, as Pluto once was thought to be before the Kuiper Belt was discovered.
With the discovery of 2012 VP113 it is now clear Sedna is not unique and is likely the second known member of the hypothesized inner Oort cloud, the likely origin of some comets.
2012 VP113’s closest orbit point to the Sun brings it to about 80 AU.
For context, the rocky planets and asteroids exist at distances ranging between .39 and 4.2 AU. Gas giants are found between 5 and 30 AU, and the Kuiper belt ranges from 30 to 50 AU. In our Solar System there is a distinct edge at 50 AU. Only Sedna was known to stay significantly beyond this outer boundary at 76 AU for its entire orbit.
This is an orbit diagram for the outer Solar System. The Sun and Terrestrial planets are at the center. The orbits of the four giant planets, Jupiter, Saturn, Uranus and Neptune, are shown by purple solid circles. The Kuiper Belt, including Pluto, is shown by the dotted light blue region just beyond the giant planets. Sedna’s orbit is shown in orange while 2012 VP113’s orbit is shown in red. Both objects are currently near their closest approach to the Sun. Image credit: Scott Sheppard.
“The search for these distant inner Oort cloud objects beyond Sedna and 2012 VP113 should continue, as they could tell us a lot about how our Solar System formed and evolved,”said Dr Sheppard, who is the second author of a paper published in the journal Nature.
The astronomers determine that about 900 objects with orbits like Sedna and 2012 VP113 and sizes larger than 1,000 km may exist and that the total population of the inner Oort cloud is likely bigger than that of the Kuiper Belt and main asteroid belt.
“Some of these inner Oort cloud objects could rival the size of Mars or even Earth. This is because many of the inner Oort cloud objects are so distant that even very large ones would be too faint to detect with current technology,” Dr Sheppard said.
Both Sedna and 2012 VP113 were found near their closest approach to the Sun, but they both have orbits that go out to hundreds of AU, at which point they would be too faint to discover.
In fact, the similarity in the orbits found for Sedna, 2012 VP113 and a few other objects near the edge of the Kuiper Belt suggests that an unknown massive perturbing body may be shepherding these objects into these similar orbital configurations.
The team suggests a Super Earth or an even larger object at hundreds of AU could create the shepherding effect seen in the orbits of these objects, which are too distant to be perturbed significantly by any of the known planets.
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Chadwick A. Trujillo & Scott S. Sheppard. 2014. A Sedna-like body with a perihelion of 80 astronomical units. Nature 507, 471–474; doi: 10.1038/nature13156
