GJ 433: A Nearby Red Dwarf with Three Known Worlds

GJ 433 is a single M1.5 star located 29.6 light-years from Earth. Its spectral class marks it as an M-type dwarf, a small, cool red star, though its temperature is 3600 K and its mass is 0.48 solar masses. Compared with the Sun, its reported mass estimate is smaller and its reported temperature is cooler. Three planets have been reported in orbit around this star, all detected by the radial velocity method, which measures the wobble a planet's gravity induces in its star's motion; repeated wobbles reveal the planet and its orbital period.

GJ 433 b was reported in 2013 and completes an orbit in 7.37 days, the shortest year among the listed planets. Its minimum mass is 6.04 Earth masses, which is larger than Earth's and the second-smallest minimum mass among the listed planets. GJ 433 c was reported in 2014 and has the longest year among the listed planets at 5090 days. Its minimum mass of 32.4 Earth masses is also the largest among the listed planets and is larger than Earth's. GJ 433 d was reported in 2020 and has the second-shortest year among the listed planets at 36.1 days. It has the smallest minimum mass among the listed planets at 5.22 Earth masses, and that minimum mass is larger than Earth's. Each minimum mass is a lower bound on the planet's true mass, a distinction from an ordinary mass estimate.