Newly-discovered dwarf planet pushes back the edge of the Solar System
By Anthony Wood
March 28, 2014
Scientists from the Carnegie Institution for Science and the Gemini Observatory have reported the existence of a new member of our solar system. The distant dwarf planet, dubbed 2012 VP113, is believed to be one of thousands of distant objects that make up the hypothesized "inner Oort cloud."
The new planetary body was discovered by Scott Sheppard of Carnegie and Chadwick Trujillo of the Gemini Observatory with the aid of the Dark Energy Camera on the NOAO telescope in Chile. The four meter telescope has the largest field of view of any telescope of its size, allowing the team to scan vast areas of the night sky for objects which are ordinarily too faint to see.
Once 2012 VP113 had been discovered, the team used the Magellan 6.5-meter telescope at Carnegie’s Las Campanas Observatory to ascertain the orbit of the dwarf planet. It was discovered that at its closest point, 2012 VP113 is roughly 80 AU from the sun (with 1 AU being the distance from the Earth to the Sun). This made the new discovery only the second planetary body to be found outside the Kuiper belt, a ring of icy objects 30 to 50 AU from the Sun, yet still under the sway of our star's gravitational pull.
The only other planetary body found to stray beyond the previously accepted 50 AU limit of our solar system was Sedna. This minor planet was believed to be unique, orbiting the Sun with a closest approach of 76 AU, however, with the discovery of 2012 VP113 it is clear that this is not the case.
Therefore, this new discovery has the effect of pushing back the boundaries of our immediate solar system. Linda Elkins-Tanton, director of Carnegie's Department of Terrestrial Magnetism underpinned this when she stated, "This is an extraordinary result that redefines our understanding of our Solar System."
This new hypothesized edge of the Solar System is being referred to as the “inner Oort Cloud.” This cloud differs from the outer Oort cloud as objects in the latter, orbiting from 1500 AU, are constantly affected by the gravity of nearby stars. However, the celestial bodies in the inner Oort cloud are free from such interference and therefore follow a more stable orbit.
It is believed that there are in excess of 900 objects present in the inner Oort cloud with similar orbits to 2012 VA113, some of which may exceed 1,000 km (620 mi) in size.
"Some of these inner Oort cloud objects could rival the size of Mars or even Earth," says Sheppard. "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."
There are three prevailing theories regarding the cause of the irregular and distant orbits of 2012 VP113 and Sedna. The first theory is that a massive planet roughly ten times the size of Earth was expelled from the ordinary orbit of giant planets. As it made its way out of the immediate Solar System it perturbed objects from the Kuiper belt, causing the irregular orbits of the newly discovered planetary bodies. However, this theory has arguably already been disproved as a recent survey by NASA's Wide-Field Infrared Survey Explorer (WISE) satellite has turned up no evidence of a Super Earth hiding in the fringes of the Solar System.
Therefore, it is most likely that either the irregular orbit is the result of a close encounter with the gravity of another star, or that the new discoveries are in fact extra-solar planets captured by the gravity of our Sun from its birth cluster. It is believed that the discovery of further planets in the hypothesized inner Oort cloud will help to shed light on the irregular orbits of these minor planets.
Source: Carnegie Institution for Science