GJ 1289 b: A Nearby Planet Around a Small Red Dwarf

GJ 1289 is an M4.5 Ve star, a small, cool red dwarf, located 27.2 light-years from Earth. Its spectral type places it in the coolest and reddest temperature class of stars. The star has a reported mass of 0.215 solar masses, smaller than the Sun's, and a reported radius of 0.245 solar radii, also smaller than the Sun's. Its reported temperature is 3180 K, cooler than the Sun's. One known planet orbits this host.

That planet is GJ 1289 b, discovered in 2024 by the radial velocity method, which measures the wobble a planet's gravity induces in its star's motion. Repeated wobbles reveal the planet and its orbital period. GJ 1289 b has a minimum mass of 6.27 Earth masses, larger than Earth's, meaning its true mass is at least this value. Its orbital period is 112 days.