About this world
HIP 41378 b is a sub-Neptune orbiting HIP 41378, a yellow-white F-type star (type F6) 347 light-years from Earth. It is about 2.6 times the size of Earth and holds 6.9 Earth masses. It completes an orbit every 15.6 days at 0.13 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 959 K (686 °C): far too hot for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium. Its atmosphere has already been studied: 2 spectroscopic observations.
It was discovered in 2016 by transit with K2. A planet crosses its star and dims it by a tiny, periodic fraction. HIP 41378 has 6 known planets; the others are HIP 41378 c, HIP 41378 g, HIP 41378 e, HIP 41378 d and HIP 41378 f.