GJ 27.1 is a cool M-dwarf (about 0.53 solar masses, 3,542 K), 23.6 light-years from Earth. GJ 27.1 b is a 13.0-Earth-mass planet, with an orbital period of 15.8 days, at 0.101 AU from its star, on an eccentric orbit (e ≈ 0.08), discovered in 2014 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. GJ 27.1 b orbits well inside Earth's distance from the Sun.