K2-266: A Cool Dwarf and Its Four Known Worlds

K2-266 is a star 253 light-years away with four planets. The star has a reported mass of 0.686 solar masses and a radius of 0.703 solar radii, both smaller than the Sun's. Its temperature of 4290 K is cooler than the Sun's.

All four planets were discovered by transit in 2018, the method in which a planet passes in front of its star and causes a small dip in observed brightness.

K2-266 b is a Neptune-like planet with a mass of 11.3 Earth masses and a radius of 3.3 Earth radii, larger than Earth's. Its orbital period is 0.659 days, the shortest among the listed planets.

K2-266 c is a Sub-Earth with a mass of 0.29 Earth masses and a radius of 0.705 Earth radii, both smaller than Earth's. Its orbital period is 7.81 days, the second-shortest among the listed planets.

K2-266 d is Neptune-like, with a mass of 8.9 Earth masses and a radius of 2.93 Earth radii, larger than Earth's. Its mean density is 1.95 g/cm³, 0.354 times Earth's. Its orbital period is 14.7 days, the second-longest among the listed planets.

K2-266 e is also Neptune-like, with a mass of 14.3 Earth masses and a radius of 2.73 Earth radii, larger than Earth's. Its mean density is 3.87 g/cm³, 0.703 times Earth's. Its orbital period is 19.5 days, the longest among the listed planets, and its radius is the second-smallest among the listed planets.