HAT-P-57 is a Sun-like F-type star (about 2.77 solar masses, 6,330 K, 1.85 solar radii), 280 light-years from Earth. HAT-P-57 b is a 1.41-Jupiter-mass companion, with an orbital period of 2.5 days, discovered in 2015 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.