Planets of the Red Dwarf GJ 328

GJ 328 is an M0.0 star, a small, cool red dwarf, located 66.9 light-years away. Two planets have been found to orbit it, both by the radial velocity method, which tracks the wobble a planet's gravity induces in its star's motion. The star has a reported mass of 0.65 solar masses and a reported radius of 0.63 solar radii, both smaller than the Sun's. Its reported temperature is 3900 K, cooler than the Sun's.

GJ 328 b was discovered in 2013. Its minimum mass is 798 Earth masses, and its orbital period is 3770 days. That minimum mass is larger than Earth's and is roughly 2.51 times Jupiter's mass. Among the listed planets, GJ 328 b has the longest year by reported estimates and the largest minimum mass.

GJ 328 c was discovered in 2023. Its minimum mass is 21.4 Earth masses, and its orbital period is 242 days. That minimum mass is larger than Earth's. Among the listed planets, GJ 328 c has the shortest year by reported estimates and the smallest minimum mass.

A minimum mass is a lower bound on a planet's true mass, which distinguishes the values reported for both worlds from an ordinary mass estimate.