HD 103720 is an orange K-type dwarf (about 0.79 solar masses, 5,017 K, 0.73 solar radii), 45.5 light-years from Earth. HD 103720 b is a 0.62-Jupiter-mass companion, with an orbital period of 4.6 days, at 0.050 AU from its star, on an eccentric orbit (e ≈ 0.09), discovered in 2014 via radial velocity. 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.