http://www.sciencedaily.com/releases/2006/08/060814115617.htm

The two objects, separated by less than 2/3 of the radius of the Sun or only a few thousandths of the distance between the Earth and the Sun, rotate around each other in about 2 hours. The brown dwarf [1] moves on its orbit at the amazing speed of 800 000 km/h!

This is neat stuff.