About this world
Kepler-1991 c is a sub-Neptune orbiting Kepler-1991, a yellow, Sun-like star 2.79 thousand light-years from Earth. It is about 2.6 times the size of Earth. It completes an orbit every 22.8 days at 0.15 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 634 K (361 °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 2023 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction. Kepler-1991 has 2 known planets; the others are Kepler-1991 b.