Kepler-228 and Its Three Worlds

Kepler-228 is a star located 5360 light-years away, and three planets have been identified in orbit around it. The host is 4.07 billion years old, with a mass of 0.95 solar masses, a radius of 0.92 solar radii, and a temperature of 5630 K. Its reported temperature is cooler than the Sun's.

All three planets were discovered by the transit method in 2014, in which a planet passing in front of its star causes a small dip in observed brightness. Kepler-228 b is a Super-Earth with a radius of 1.53 Earth radii and an orbital period of 2.57 days; among the listed planets, it has the shortest year and the smallest radius by reported estimates. Kepler-228 c is Neptune-like, with a radius of 2.7 Earth radii and an orbital period of 4.13 days, the second-shortest year and second-smallest radius among the listed planets. Kepler-228 d is Jupiter-like, with a radius of 4.04 Earth radii and an orbital period of 11.1 days, giving it the longest year and the largest radius among the listed planets. The radii of Kepler-228 c and Kepler-228 d are each larger than Earth's, as is that of Kepler-228 b.