About this world
KMT-2021-BLG-1391L b is a super-Earth orbiting KMT-2021-BLG-1391L, a star 18.7 thousand light-years from Earth. It is about 2 times the size of Earth (its size estimated from its mass) and holds 4.5 Earth masses.
At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2022 by microlensing with KMTNet. A foreground star's gravity magnifies a background star; a planet adds a blip.