About this world
HD 220197 b is a Neptune-like planet orbiting HD 220197, a yellow, Sun-like star (type G5) 210 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 4.73 years at 2.7 AU from its star.
Its equilibrium temperature is about 164 K (−109 °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 2018 by radial velocity with Roque de los Muchachos Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.