About this world
HIP 41378 g is a sub-Neptune orbiting HIP 41378, a yellow-white F-type star (type F6) 347 light-years from Earth. It is about 2.5 times the size of Earth (its size estimated from its mass) and holds 6.8 Earth masses. It completes an orbit every 63.2 days at 0.33 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 605 K (332 °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 W. M. Keck Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. HIP 41378 has 6 known planets; the others are HIP 41378 b, HIP 41378 c, HIP 41378 e, HIP 41378 d and HIP 41378 f.