Aten System

Aten is a supermassive black hole at the center of the galaxy. It was discovered when another theory about the center of the universe was put out, stating that the center was not Kerbin, Kerbol or Khnum but another larger entity that did not emit light and we could only discover by alternate means. Alternate means being a huge gas cloud being thrown around by the object due to it's immense gravitation pull. However, this universe theory was proved false when another object was discovered with greater gravity. (The Abyss)

Description
Aten is the supermassive black hole at the center of the galaxy that Khnum, Amun and other stars orbit.

The Discovery of The Abyss
The Kerbals thought it was stationary until they discovered The Abyss, an ultramassive black hole that was once the center of a former galaxy, but they all fell in to the black hole, and now there is only a small cluster of 6 or so objects revolving around the black hole, mostly brown dwarfs and stellar remnants. Aten orbits the Abyss from a great distance.