Kepler-173 and Its Two Known Planets

Kepler-173 is a star located 2720 light-years away, and it hosts two known planets. The star is 3.98 billion years old, has a mass of 1.04 solar masses, a radius of 1.06 solar radii, and a temperature of 5930 K. That temperature is hotter than the Sun's.

Both 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-173 b is classified as Earth-like, a size class that stays within 1.5 times Earth's radius. It has an orbital period of 4.26 days and a radius of 1.29 Earth radii, the smallest radius among the listed planets and the shortest orbital period among them as well. Kepler-173 c is classified as a Super-Earth, a size class reaching up to 2.5 times Earth's radius. Its orbital period is 8.01 days, the longest among the listed planets, and its radius of 2.43 Earth radii is larger than Earth's and the largest among the listed planets.