K2-151: A Nearby Red Dwarf with One Known Planet

K2-151 is an M1.5 V star located 227 light-years away, a small, cool red dwarf with one known planet in orbit. Its spectral type places it among the coolest and reddest stellar classes, with the trailing V marking it as a main-sequence dwarf. The star has a reported mass of 0.44 solar masses, a radius of 0.429 solar radii, and a temperature of 3590 K. All three values are smaller or cooler than the Sun's corresponding figures, though the mass and radius are estimates.

The single planet, K2-151 b, was discovered in 2018 by the transit method, in which a planet passing in front of its star causes a small dip in observed brightness. Repeated dips help establish the planet's orbital period. K2-151 b completes one orbit every 3.84 days, and its radius is 1.49 Earth radii, larger than Earth's. That radius places it within the Earth-like size class, which spans planets up to 1.5 times Earth's radius.