Well, could this be planet x that was just discovered....
Astronomers have sighted a very dense planet-sized object that orbits its parent star in just four days and six hours.
The object, COROT-exo-3b, fits into the category of a failed star known as a brown dwarf, but the team that made the discovery has not ruled out the possibility that it is a planet. Brown dwarfs are failed stars. They burn lithium but are not massive enough to generate the thermonuclear fusion of hydrogen and helium that powers real stars. Planets do none of that.
http://www.space.com/scienceastronom...xo-object.html