A 1.9 Earth Radius Rocky Planet and the Discovery of a Non-Transiting Planet in the Kepler-20 System
Lars A. Buchhave et al 2016 AJ 152 160
New observations of the Kepler-20 solar system characterize the 1.8 Earth-radius Kepler-20b as the most massive planet with a likely rocky composition found, and reveal a sixth planet that doesn’t transit.