HIP 79431 is a cool M-dwarf (about 0.49 solar masses, 3,191 K), 14.5 light-years from Earth. HIP 79431 b is a 2.10-Jupiter-mass companion, with an orbital period of 112 days, at 0.360 AU from its star, on an eccentric orbit (e ≈ 0.29), discovered in 2009 via radial velocity. The planet betrayed itself through the star's reflex motion — a technique that first revealed worlds around Sun-like stars in the 1990s and remains a workhorse of exoplanet discovery. The planet's marked eccentricity suggests past scattering events or perturbations from unseen companions.