About this world
HD 218566 b is a Neptune-like planet orbiting HD 218566, an orange dwarf (type K3V) 94 light-years from Earth. It is about 0.83 times the size of Jupiter (its size estimated from its mass), with at least 0.2 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 226 days at 0.69 AU from its star, on a strongly elongated orbit (e = 0.3).
Its equilibrium temperature is about 253 K (−20 °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 2010 by radial velocity with W. M. Keck Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.