KELT-15 is a Sun-like F-type star (about 2.06 solar masses, 6,003 K, 1.78 solar radii), 325 light-years from Earth. KELT-15 b is a 1.31-Jupiter-mass companion, with an orbital period of 3.3 days, discovered in 2016 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 (19.5 Earth radii) indicates a bloated atmosphere heated by intense stellar radiation.