TOI-4603 is a Sun-like F-type star (about 1.76 solar masses, 6,264 K, 2.74 solar radii), 226 light-years from Earth. TOI-4603 b is a 12.9-Jupiter-mass companion, with an orbital period of 7.2 days, at 0.089 AU from its star, and an equilibrium temperature near 1,677 K, on an eccentric orbit (e ≈ 0.33), discovered in 2023 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.