Kepler-339 and Its Three Known Planets

Kepler-339 is a star located 2010 light-years away. It has an age of 4.37 billion years, a mass of 0.93 solar masses, a radius of 0.9 solar radii, and a temperature of 5570 K. Its reported mass estimate is smaller than the Sun's, and its reported temperature is cooler than the Sun's. Three planets are known to orbit this host.

All three planets were discovered in 2014 by the transit method, in which a planet passes in front of its star from our viewpoint and causes a small dip in observed brightness. Kepler-339 b, Kepler-339 c, and Kepler-339 d are all Earth-like in size class, meaning each stays within 1.5 times Earth's radius. Kepler-339 b has a radius of 1.42 Earth radii and an orbital period of 4.98 days, the shortest year among the listed planets. Kepler-339 c has a radius of 1.15 Earth radii and an orbital period of 6.99 days, the second-shortest year among them. Kepler-339 d has a radius of 1.17 Earth radii and an orbital period of 10.6 days, the longest year among the listed planets. Among these planets, Kepler-339 b has the largest radius, Kepler-339 c has the smallest, and Kepler-339 d has the second-smallest.