About this world
Kepler-31 d is a sub-Neptune orbiting Kepler-31, a yellow-white F-type star 5.43 thousand light-years from Earth. It is about 3.9 times the size of Earth and holds 2,161 Earth masses. It completes an orbit every 87.6 days at 0.4 AU from its star.
Its equilibrium temperature is about 484 K (211 °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 2014 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction. Kepler-31 has 3 known planets; the others are Kepler-31 b and Kepler-31 c.