About this world
KMT-2021-BLG-0909L b is a gas giant orbiting KMT-2021-BLG-0909L, a star 21.1 thousand light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass) and holds 1.3 Jupiter masses.
At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2023 by microlensing with KMTNet. A foreground star's gravity magnifies a background star; a planet adds a blip.