K2-165: A Cool Dwarf with Three Transiting Worlds

K2-165 is a star located 439 light-years away, and it hosts three known planets. The star itself has a reported mass of 0.868 solar masses, a radius of 0.838 solar radii, and a temperature of 5140 K, making it less massive, smaller, and cooler than the Sun.

All three planets were discovered in 2018 by the transit method, in which a planet passing in front of its star from our viewpoint causes a small dip in observed brightness; repeated dips help establish orbital periods. K2-165 b is an Earth-like planet with a radius of 1.27 Earth radii and an orbital period of 2.35 days, the shortest year among the listed planets. K2-165 c is a Super-Earth with a radius of 1.55 Earth radii and an orbital period of 4.38 days, the second-shortest among the trio. K2-165 d is a Neptune-like planet with a radius of 2.65 Earth radii and an orbital period of 14.1 days, the longest year among the listed planets. Each planet's radius is larger than Earth's, with K2-165 b having the smallest radius and K2-165 d the largest among the listed planets.