Have we found the inner Oort Cloud?

In our solar system, we have the inner planets (Mercury, Venus, Earth, Mars), the Asteroid Belt, the outer planets (Jupiter, Saturn, Uranus, Neptune), and the Kuiper Belt (including Pluto, Sedna, and a few others). There is also the Oort Cloud, which was proposed by Jan Oort. The Oort Cloud is hypothetical — we don’t really know that it exists, but we think it does. Now it looks like we may be finding things in the inner Oort Cloud.

Kuiper_oortThe Oort Cloud is supposed to be a roughly spherical region surrounding the Sun. It contains icy clumps, and is the source for long period comets. The inner part of the cloud is disc shaped, and probably connects to the Kuiper Belt.

Now Chadwick Trujillo and Scott Shepherd have found 2012 VP113 (which they call Biden), another object like Sedna. This is the furthest object found in our solar system. They think that Sedna and Biden may be members of the inner Oort Cloud.

Biden has a diameter of about 450 km, and is about 80 AU at its closest approach to the sun, and about 450 AU for aphelion. It takes over 4000 years to go around the sun once. It’s remarkable that they were able to find it at all given that it is so far away and is so small.

Current models of solar system formation don’t have anything forming in the region where Sedna and Biden are. Either these models are wrong, or these objects formed closer in, and then were flung far out. But I would think that then their perihelion should be much closer in. Hopefully we can find more objects in this region and learn more about it.