The HD 39091 System and Its Three Worlds

HD 39091 is a G-type main-sequence star, or G0 V, located 59.6 light-years from Earth. It is a single-star system with three known planets, and its age is 2.98 billion years. The star's mass is 1.09 solar masses, larger than the Sun's, and its radius of 1.1 solar radii is also larger than the Sun's. With a temperature of 6040 K, it is hotter than the Sun.

The most massive of the three worlds is HD 39091 b, discovered in 2001 by the radial velocity method, which detects the wobble a planet's gravity induces in its star. Its mass estimate is 4480 Earth masses, roughly 14.1 times Jupiter's mass and larger than Earth's, and it completes one orbit every 2090 days - the longest year among the listed planets.

pi Men c is a Super-Earth discovered in 2018 by the transit method, which identifies the small dip in brightness when a planet crosses in front of its star. Its radius is 2.02 Earth radii, larger than Earth's, and it orbits in just 6.27 days, the shortest year among the listed planets.

pi Men d, discovered in 2022 by radial velocity, has a minimum mass of 13.4 Earth masses, larger than Earth's. A minimum mass is a lower bound on a planet's true mass, so the actual figure could be higher. Its orbital period is 125 days, the second-shortest year among the listed planets.