KELT-3 is a Sun-like F-type star (about 1.96 solar masses, 6,304 K, 1.70 solar radii), 210 light-years from Earth. KELT-3 b is a 1.94-Jupiter-mass companion, with an orbital period of 2.7 days, discovered in 2013 via transit. The inner world is a hot Jupiter — a gas giant hugging its star at a fraction of Mercury's distance — a class that forced astronomers to rethink how giant planets form and migrate inward. The planet's large radius (17.5 Earth radii) indicates a bloated atmosphere heated by intense stellar radiation.