The Iron-Rich Core and Scorched Terranes of Exoplanet K2-229 b
Located approximately 339 light-years from Earth in the constellation Pisces, the exoplanet K2-229 b represents one of the most structurally dense terrestrial worlds ever confirmed. Discovered in 2018 through high-precision transit photometry during the extended K2 mission of NASA's Kepler Space Telescope , followed by radial velocity measurements from the High Accuracy Radial Velocity Planet Searcher (HARPS), this extraordinary planet has fundamentally altered theoretical models of planetary formation. Classified as an ultra-short-period " super-Mercury ," K2-229 b possesses a radius roughly 1.17 times that of Earth, yet holds a mass nearly 2.59 times greater. This extreme disproportion yields a mean bulk density of approximately 13.1 grams per cubic centimeter—nearly double that of Earth and comparable to pure metallic iron under immense pressures. An Extreme Terrestrial Archetype in Deep Space The host star, K2-229 (cataloged as EPIC 228801451), is an active...