Kepler-36: A Two-Planet System in a Distant Stellar Neighborhood

Kepler-36 is a star located 1720 light-years away. It hosts two planets. The star itself is estimated to be 6.8 billion years old, with a mass of 1.07 solar masses and a radius of 1.63 solar radii. Its temperature is 5910 K. Each of these stellar measurements is larger or hotter than the corresponding value for the Sun.

Both planets were discovered in 2012 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-36 b is classified as Earth-like, while Kepler-36 c is classified as Neptune-like. These classes describe radius relative to Earth: an Earth-like planet stays within 1.5 times Earth's radius, and a Neptune-like planet reaches 4 times Earth's radius. The classifications do not indicate composition.

Kepler-36 b has a radius of 1.5 Earth radii and a mass of 3.83 Earth masses, both larger than Earth's corresponding values. Its mean density is 6.28 g/cm³, 1.14 times Earth's. It completes one orbit in 13.9 days. Among the listed planets, Kepler-36 b has the shortest year, the smallest radius, and the smallest reported mass.

Kepler-36 c has a radius of 3.68 Earth radii and a mass of 7.13 Earth masses, both larger than Earth's. Its mean density is 0.789 g/cm³, 0.143 times Earth's. Its orbital period is 16.2 days. Among the listed planets, Kepler-36 c has the longest year, the largest radius, and the largest reported mass.