TOI-771: A Cool Red Dwarf with Two Known Planets

TOI-771 is an M3 star, a small, cool red dwarf, located 82.4 light-years away. It has 0.22 solar masses and 0.232 solar radii, and its temperature is 3370 K. The star's reported mass and radius estimates are smaller than the Sun's, and its reported temperature is cooler than the Sun's. Two planets orbit this host.

TOI-771 b was discovered by transit in 2024. It is an Earth-like planet, meaning its radius stays within 1.5 times Earth's radius. Its radius is 1.36 Earth radii, larger than Earth's, and its mass is 2.47 Earth masses, also larger than Earth's. Its mean density is 5.41 g/cm³, 0.982 times Earth's. It completes an orbit every 2.33 days, the shortest year among the listed planets.

TOI-771 c was discovered by radial velocity in 2025. That method measures the wobble a planet's gravity induces in its star's motion; repeated wobbles reveal the planet and its orbital period. TOI-771 c has a minimum mass of 2.87 Earth masses, larger than Earth's. Its orbital period is 7.61 days, the longest year among the listed planets.