About this world
Kepler-401 d is a sub-Neptune orbiting Kepler-401, a yellow-white F-type star 3.15 thousand light-years from Earth. It is about 2.3 times the size of Earth. It completes an orbit every 184 days at 0.67 AU from its star.
Its equilibrium temperature is about 380 K (107 °C): too cold for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2016 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction. Kepler-401 has 3 known planets; the others are Kepler-401 b and Kepler-401 c.