HAT-P-23 is a Sun-like G-type star (about 1.13 solar masses, 5,905 K, 1.20 solar radii), 365 light-years from Earth. HAT-P-23 b is a 2.09-Jupiter-mass companion, with an orbital period of 1.2 days, at 0.023 AU from its star, and an equilibrium temperature near 2,056 K, on an eccentric orbit (e ≈ 0.11), discovered in 2010 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.