About this world
HIP 79431 b is a gas giant orbiting HIP 79431, a cool red dwarf (type M3V) 47.4 light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass), with at least 2.1 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 112 days at 0.36 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.29).
Its equilibrium temperature is about 177 K (−96 °C), which places it in the optimistic 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 2009 by radial velocity with W. M. Keck Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.