Kepler-209 and Its Two Planets

Kepler-209 is a star 1880 light-years away with two known planets. The star is 4.47 billion years old, with a mass of 0.95 solar masses, a radius of 0.92 solar radii, and a temperature of 5560 K. Its reported mass and radius estimates are smaller than the Sun's, and its reported temperature is cooler than the Sun's.

Both planets were discovered by transit in 2014, the method in which a planet passes in front of its star from our viewpoint and causes a small dip in observed brightness. Kepler-209 b is a Super-Earth with an orbital period of 16.1 days and a radius of 2.26 Earth radii. Kepler-209 c is Neptune-like, with an orbital period of 41.7 days and a radius of 3.1 Earth radii. Both reported radius estimates are larger than Earth's. Among the listed planets, Kepler-209 b has the shortest year and the smallest radius, while Kepler-209 c has the longest year and the largest radius.