Kepler-406: A Star and Its Two Planets

Kepler-406 is a star located 1190 light-years away, and two planets have been found orbiting it. The star is 5.84 billion years old and has a mass of 1.07 solar masses and a radius of 1.07 solar radii, both larger than the Sun's corresponding values. Its temperature of 5540 K is cooler than the Sun's.

The two planets, Kepler-406 b and Kepler-406 c, were both discovered in 2014 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. Repeated dips help establish orbital periods.

Kepler-406 b is classified as Earth-like, meaning its radius stays within 1.5 times Earth's. Its radius of 1.43 Earth radii is larger than Earth's, and among the listed planets it has the largest radius. Its mass of 6.35 Earth masses is also larger than Earth's and is the largest reported mass among the listed planets. Its mean density is 12 g/cm³, 2.17 times Earth's. It completes an orbit in 2.43 days, the shortest year among the listed planets. Kepler-406 c is classified as Sub-Earth, meaning it is smaller than Earth. Its radius of 0.85 Earth radii is smaller than Earth's and is the smallest among the listed planets. Its mass is 2.71 Earth masses, the smallest reported mass among the listed planets, and its mean density is 24.3 g/cm³, 4.41 times Earth's. It orbits in 4.62 days, the longest year among the listed planets.