Kepler-311 and Its Three Worlds

Kepler-311 is a star located 2540 light-years away. It is 4.17 billion years old and has a mass of 1.08 solar masses, a radius of 1.13 solar radii, and a temperature of 6010 K. Its reported mass and radius estimates are both larger than the Sun's, and its reported temperature is hotter than the Sun's. Three planets orbit this host.

Kepler-311 b and Kepler-311 c were both discovered by transit in 2014, while Kepler-311 d was found by the same method in 2023. A transit occurs when a planet passes in front of its star from our viewpoint, causing a small dip in observed brightness; repeated dips help establish orbital periods. That orbital period is the time a planet takes to complete one orbit, or its year. Among the listed planets, Kepler-311 b has the shortest year, at 9.18 days, and Kepler-311 c has the second-shortest, at 19.7 days.

Kepler-311 b is a Super-Earth with a radius of 1.7 Earth radii, and Kepler-311 d is also a Super-Earth, with a radius of 2.05 Earth radii. Kepler-311 c is Earth-like and has a radius of 1.43 Earth radii. 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. Each of the three planets has a reported radius estimate larger than Earth's. Among the listed planets, Kepler-311 c has the smallest radius, Kepler-311 b has the second-smallest, and Kepler-311 d has the largest.

Kepler-311 d takes 232 days to complete one orbit, the longest year among the listed planets.