About this world
pi Men d is a sub-Neptune orbiting HD 39091, a yellow, Sun-like star (type G0V) 59.6 light-years from Earth. It is about 3.7 times the size of Earth (its size estimated from its mass), with at least 13 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 125 days at 0.51 AU from its star, on a strongly elongated orbit (e = 0.22).
Its equilibrium temperature is about 444 K (170 °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 2022 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. HD 39091 has 3 known planets; the others are pi Men c and HD 39091 b.