About this world
HD 21693 b is a sub-Neptune orbiting HD 21693, a yellow, Sun-like star (type G8V) 108 light-years from Earth. It is about 2.8 times the size of Earth (its size estimated from its mass), with at least 8.2 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 22.7 days at 0.15 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 656 K (383 °C): far too hot for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2019 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. HD 21693 has 2 known planets; the others are HD 21693 c.