K2-73 and Its Two Planets

K2-73 is a star 878 light-years away with 1.06 solar masses and 1.06 solar radii, and a temperature of 5870 K, with a radius larger than the Sun's. Two planets orbit this host.

K2-73 b is a Neptune-like planet discovered by transit in 2016, with a mass of 9.2 Earth masses, a radius of 2.58 Earth radii, and an orbital period of 7.5 days. It has a mean density of 2.95 g/cm³, 0.536 times Earth's, the shortest reported year among the listed planets, and both its mass and radius are larger than Earth's.

K2-73 c was discovered by radial velocity in 2025, a method that measures the wobble a planet's gravity induces in its star's motion. Its minimum mass is 1140 Earth masses, and its orbital period is 1000 days, the longest reported year among the listed planets, with a minimum mass roughly 3.59 times Jupiter's mass.