Kepler-157: A Distant Star With Three Known Planets

Kepler-157 is a star located 2520 light-years away, and three planets have been found in orbit around it. The host star is 4.07 billion years old and contains 1.02 solar masses. Its radius is 1.03 solar radii, and its temperature is 5870 K, which is hotter than the Sun's.

The planets were all detected 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-157 b was discovered in 2014. It is classified as Earth-like, with a radius of 1.32 Earth radii and an orbital period of 1.73 days. Kepler-157 c was also discovered in 2014. It is classified as a Super-Earth, with a radius of 2.24 Earth radii and an orbital period of 13.5 days. Kepler-157 d was discovered in 2016. It is also classified as Earth-like, with a radius of 1.46 Earth radii and an orbital period of 7.03 days.

All three planets have reported radius estimates larger than Earth's. Among the listed planets, Kepler-157 b has the shortest year by reported estimates, at 1.73 days, and the smallest radius, at 1.32 Earth radii. Kepler-157 c has the longest year by reported estimates, at 13.5 days, and the largest radius, at 2.24 Earth radii. Kepler-157 d has the second-shortest year by reported estimates, at 7.03 days, and the second-smallest radius, at 1.46 Earth radii.

Planet size classes compare radius with Earth's. An Earth-like planet stays within 1.5 times Earth's radius, while a Super-Earth reaches 2.5 times. These classifications describe radius, not composition.