Two Planets Orbiting HIP 111909

HIP 111909 is a K1 III star 287 light-years away with two known planets. The star is 4.3 billion years old and has 1.28 solar masses, 4.53 solar radii, and a temperature of 4890 K. Its reported mass and radius are larger than the Sun's, and its reported temperature is cooler than the Sun's.

HIP 111909 b was discovered in 2025 by radial velocity, a method that measures the wobble a planet's gravity induces in its star's motion; repeated wobbles reveal the planet and its orbital period. The planet has a minimum mass of 385 Earth masses, a lower bound on its true mass, and an orbital period of 487 days. Its minimum mass is larger than Earth's and roughly 1.21 times Jupiter's mass. Among the listed planets, HIP 111909 b has the shortest year by reported estimates and the largest minimum mass.

HIP 111909 c was also discovered in 2025 by radial velocity. It has a minimum mass of 257 Earth masses, a lower bound on its true mass, and an orbital period of 894 days. Its minimum mass is larger than Earth's. Among the listed planets, HIP 111909 c has the longest year by reported estimates and the smallest minimum mass.