Proxima Cen: A Nearby Red Dwarf and Its Two Known Planets

Proxima Cen is an M5.5 V star - a small, cool red dwarf - located 4.24 light-years away. Its mass is 0.12 solar masses, its radius is 0.141 solar radii, and its temperature is 3050 K. Each of these values is smaller or cooler than the corresponding value for the Sun. Two planets are known to orbit this host.

Proxima Cen b was discovered in 2016 by the radial velocity method, which detects the wobble a planet's gravity induces in its star. Its minimum mass is 1.06 Earth masses, and its orbital period is 11.2 days. Proxima Cen d, also found by radial velocity, was discovered in 2025. Its minimum mass is 0.26 Earth masses, and its orbital period is 5.12 days. A minimum mass is a lower bound on a planet's true mass, so these figures do not give exact masses.

Among the listed planets, Proxima Cen d has the shortest year by reported estimates at 5.12 days and the smallest minimum mass, while Proxima Cen b has the longest year at 11.2 days and the largest minimum mass. Proxima Cen d's minimum mass is also smaller than Earth's.