GJ 251 is a star with 0.36 times the mass of the Sun, and 0.36 times its radius. It is located 18.20 light years away from the solar system.
GJ 251 is known to have 1 exoplanets in orbit around it.
GJ 251 b was discovered by the W. M. Keck Observatory observatory, in 2020-11, using the radial velocity method. Its semi-major axis is 0.08 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of GJ 251 b is 4.004 times the mass of Earth. The radius of GJ 251 b is 1.830 that of Earth. At 4.004 Earth masses, GJ 251 b is a so called Super Earth. Super Earths could be terrestrial worlds like Earth, but they could also be ocean worlds or terrestrial worlds wrapped in a substantial atmosphere, in which case some refer to them as Mini Neptunes. No Super Earths are known to exist in our solar system, but if it exists, the so-called Planet Nine could very well be a super Earth, as it is hypothesized to have a mass between five and ten Earth masses.