About this world
GJ 2126 b is a gas giant orbiting GJ 2126, a cool red dwarf (type M0V) 124 light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass), with at least 1.3 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 273 days at 0.71 AU from its star, on a strongly elongated orbit (e = 0.85).
Its equilibrium temperature is about 203 K (−70 °C), which places it in the conservative habitable zone: the band where liquid water could exist on a rocky surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2025 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.