About this world
HIP 81991 b is a gas giant orbiting HIP 81991, a yellow, Sun-like star (type G8V) 143 light-years from Earth. It is about 1.1 times the size of Jupiter (its size estimated from its mass) and holds 9.5 Jupiter masses. It completes an orbit every 16 years at 6.4 AU from its star.
Its equilibrium temperature is about 163 K (−110 °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 2026 by radial velocity with Multiple Facilities. The star wobbles toward and away from us, Doppler-shifting its spectrum.