Kepler-23: A Distant Star With Three Known Worlds

Kepler-23 is a star located 2730 light-years away, and it hosts three known planets. The star is estimated to be 6 billion years old, with a mass of 1.11 solar masses and a radius of 1.52 solar radii, making its reported radius estimate larger than the Sun's. Its temperature is 5760 K.

The planets were all found 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-23 b was discovered in 2011 and is classified as a Super-Earth. It has a mass of 2.56 Earth masses, a radius of 1.64 Earth radii, and an orbital period of 7.1 days. Among the listed planets, it has the shortest year, the smallest radius, and the smallest reported mass, and its mean density is 3.21 g/cm³, 0.583 times Earth's.

Kepler-23 c was also discovered in 2011 and is classified as Neptune-like. Its mass is 7.81 Earth masses, its radius is 3.01 Earth radii, and its orbital period is 10.7 days. Among the listed planets, it has the second-shortest year and the largest radius and reported mass, and its mean density is 1.59 g/cm³, 0.288 times Earth's.

Kepler-23 d was discovered in 2014 and is classified as a Super-Earth. It has a mass of 4.44 Earth masses, a radius of 2.21 Earth radii, and an orbital period of 15.3 days. Among the listed planets, it has the longest year and the second-smallest radius and reported mass, and its mean density is 2.28 g/cm³, 0.414 times Earth's. Each planet's reported radius and mass estimates are larger than Earth's.