About this world
GJ 508.2 b is a gas giant orbiting GJ 508.2, a cool red dwarf (type M1.0V) 54.3 light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass), with at least 1.9 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 14.5 years at 4.8 AU from its star, on a strongly elongated orbit (e = 0.27).
Its equilibrium temperature is about 59 K (−214 °C): too cold for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2025 by radial velocity with Calar Alto Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.