The Planets of GJ 357

GJ 357 is an M2.5 V star, a small, cool red dwarf, located 30.8 light-years away. Its mass is 0.342 solar masses, its radius is 0.337 solar radii, and its temperature is 3510 K, all smaller or cooler than the Sun's corresponding values. Three planets are known to orbit this star: GJ 357 b, GJ 357 c, and GJ 357 d.

GJ 357 b was discovered in 2019 by the transit method, which detects the small dip in a star's brightness when a planet crosses in front of it. This planet's radius is 1.2 Earth radii, making it larger than Earth and placing it within the Earth-like size class, and its orbital period is 3.93 days, the shortest year among the listed planets.

GJ 357 c and GJ 357 d were both discovered in 2019 by the radial velocity method, which measures the wobble a planet's gravity induces in its star. GJ 357 c has a minimum mass of 3.4 Earth masses and an orbital period of 9.12 days, the second-shortest year among the listed planets. GJ 357 d has a minimum mass of 6.1 Earth masses and an orbital period of 55.7 days, the longest year among the listed planets. Both minimum masses are larger than Earth's.