Found record for density planets system:
The star system KOI-500 identified five planets, all of which revolve around the star at a distance much smaller than the distance from Mercury to the Sun.
Discovered ultracompact system of five exoplanets. Astronomers have discovered the most compact system of the five exoplanets.
The size of their orbits does not exceed one twelfth of the radius of Earth's orbit. On the discovery at a press conference of the American Astronomical Society, said Darin Ragozzin, of the University of Florida.