About this world
Kepler-991 b is a sub-Neptune orbiting Kepler-991, an orange dwarf 1.27 thousand light-years from Earth. It is about 2.5 times the size of Earth. It completes an orbit every 82.5 days at 0.31 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 260 K (−13 °C), which places it in the optimistic habitable zone: the band where liquid water could exist on a rocky 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.