About this world
Kepler-126 d is a sub-Neptune orbiting Kepler-126, a yellow-white F-type star 774 light-years from Earth. It is about 2.5 times the size of Earth, with at least 55 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 100 days at 0.45 AU from its star.
Its equilibrium temperature is about 475 K (202 °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 2014 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction. Kepler-126 has 3 known planets; the others are Kepler-126 b and Kepler-126 c.