About this world
HD 154088 b is a sub-Neptune orbiting HD 154088, an orange dwarf (type K0IV-V) 59.6 light-years from Earth. It is about 2.5 times the size of Earth (its size estimated from its mass), with at least 6.6 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 18.6 days at 0.13 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.34).
Its equilibrium temperature is about 690 K (417 °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 2021 by radial velocity with La Silla Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.