A Second Sedna
- Title: A Sedna-like body with a perihelion of 80 astronomical units
- Authors: C. A. Trujillo & S. S. Sheppard
Sedna, a dwarf planet that resides far out in the depths of the solar system, is the first known objects that belongs to the inner Oort cloud. Discovered in 2003, Sedna became a very important trans-Neptunian object, aiding in the quest to learn about the evolution of the Solar System. With a perihelion of 76 AU, Sedna was the farthest known body in the Solar System. Recently, an object called 2012VP113 was found to be another inner Oort cloud object. This confirms that Sedna is not an isolated body and that there may be more inner Oort cloud objects out there.
The authors conducted a sky survey that focused on objects with perihelion distances between 50 AU to around 300 AU. 2012VP113 was found to have a perihelion distance of 80 AU, making it farther away from the Sun than Sedna is. The surface color of 2012VP113 is moderately red, which is consistent with formation in the gas giant region, not in the classical Kuiper belt region.
An important question from the discoveries of Sedna and 2012VP113 is how do these inner Oort cloud objects form? Currently there are two preferred models, along with one lesser studied model. One model explores the possibility that a Kuiper belt object is perturbed by some planet-sized object out towards the inner Oort cloud region. The next model suggests that inner Oort cloud objects could have been created from a close stellar encounter during the formation of the early Solar System. The third model suggests that inner Oort cloud objects could be extrasolar planetesimals captured in the formation of the early Solar System. Each theory has different possibilities, and the discovery of additional inner Oort cloud objects would provide more insight into the formation of these bodies as well as our Solar System.
Image: A combination of three images showing 2012VP113, each taken two hours apart, on November 5, 2012. (Credit: Scott S. Sheppard/Carnegie Institution for Science)