gam Lib: A K-Type Giant With Two Known Planets

gam Lib is a star located 155 light-years away with two planets orbiting it. The host is a K0 III star, a classification indicating a cooler temperature class than the Sun, and its spectral type places it among the giant stars. It has an age of 2.82 billion years, a mass of 1.47 solar masses, a radius of 11.1 solar radii, and a temperature of 4820 K. Its reported mass estimate is larger than the Sun's, its reported radius estimate is larger than the Sun's, and its reported temperature is cooler than the Sun's.

The two planets are gam Lib b and gam Lib c, both discovered in 2018 by the radial velocity method, which measures the wobble a planet's gravity induces in its star's motion. gam Lib b has a minimum mass of 358 Earth masses and an orbital period of 415 days. Its minimum mass is larger than Earth's and roughly 1.13 times Jupiter's mass. Among the listed planets, gam Lib b has the shortest year by reported estimates.

gam Lib c has a minimum mass of 1660 Earth masses and an orbital period of 966 days. Its minimum mass is larger than Earth's and roughly 5.23 times Jupiter's mass. Among the listed planets, gam Lib c has the longest year by reported estimates and the largest minimum mass.

A minimum mass is a lower bound on a planet's true mass, distinct from an ordinary mass estimate. The radial velocity method reveals a planet and its orbital period through repeated wobbles in the star's motion.