About this world
HD 217958 b is a gas giant orbiting HD 217958, a yellow, Sun-like star 202 light-years from Earth. It is about 1.3 times the size of Jupiter (its size estimated from its mass) and holds 0.52 Jupiter masses. It completes an orbit every 7.01 years at 3.8 AU from its star.
Its equilibrium temperature is about 170 K (−103 °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 2022 by radial velocity with Multiple Observatories. The star wobbles toward and away from us, Doppler-shifting its spectrum.