About this world
Kepler-129 b is a sub-Neptune orbiting Kepler-129, a yellow, Sun-like star (type G4V) 1.33 thousand light-years from Earth. It is about 2.4 times the size of Earth, with at least 20 Earth masses (a minimum, measured by radial velocity). It completes an orbit every 15.8 days at 0.13 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 910 K (637 °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-129 has 3 known planets; the others are Kepler-129 c and Kepler-129 d.