About this world
HD 191939 g is a sub-Neptune orbiting HD 191939, a yellow, Sun-like star (type G9V) 175 light-years from Earth. It is about 3.7 times the size of Earth (its size estimated from its mass), with at least 14 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 284 days at 0.81 AU from its star.
Its equilibrium temperature is about 278 K (5 °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 2022 by radial velocity with Multiple Observatories. The star wobbles toward and away from us, Doppler-shifting its spectrum. HD 191939 has 6 known planets; the others are HD 191939 b, HD 191939 c, HD 191939 d, HD 191939 e and HD 191939 f.