GJ 338 B is a star with 0.64 times the mass of the Sun, and 0.58 times its radius. It is located 20.65 light years away from the solar system and is estimated to be 4 billion years old, as compared to the Sun which is roughly 4.6 billion years old.
GJ 338 B is known to have 1 exoplanets in orbit around it.
GJ 338 B b was discovered by the Calar Alto Observatory observatory, in 2020-05, using the radial velocity method. Its semi-major axis is 0.14 astronomical units, as compared to Earth's which is 1 astronomical unit. The mass of GJ 338 B b is 10.275 times the mass of Earth. The radius of GJ 338 B b is 3.190 that of Earth. At more than 10 Earth masses, GJ 338 B b is an ice giant, a planet that is made up mostly of volatiles like water, amonia and methane, and enveloped by a dense hydrogen and helium atmosphere, much like Uranus and Neptune in our solar system.