About this world
HD 86728 b is a sub-Neptune orbiting HD 86728, a yellow, Sun-like star (type G1V) 48.7 light-years from Earth. It is about 3 times the size of Earth (its size estimated from its mass), with at least 9.4 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 31.2 days at 0.19 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 687 K (414 °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 2025 by radial velocity with Multiple Observatories. The star wobbles toward and away from us, Doppler-shifting its spectrum.