Kepler-54: A Cool Dwarf and Its Three Small Worlds

Kepler-54 is a star located 886 light-years away. It has a spectral type of M1 V, making it an M-type main-sequence dwarf. Its mass is 0.48 solar masses, its radius is 0.46 solar radii, and its reported temperature is 3760 K. The star's reported mass and radius estimates are both smaller than the Sun's, and its reported temperature is cooler than the Sun's. It is estimated to be 4.17 billion years old. Three planets are known to orbit this host.

All three planets were 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-54 b and Kepler-54 c were both discovered in 2012, while Kepler-54 d was discovered in 2014.

Kepler-54 b is classified as a Super-Earth, with an orbital period of 8.01 days and a radius of 2.1 Earth radii. It has the shortest year and the largest radius among the listed planets. Kepler-54 c is classified as Earth-like, with an orbital period of 12.1 days and a radius of 1.23 Earth radii. It has the second-shortest year and the smallest radius among the listed planets. Kepler-54 d is classified as a Super-Earth, with an orbital period of 21 days and a radius of 1.53 Earth radii. It has the longest year and the second-smallest radius among the listed planets. Each planet's reported radius estimate is larger than Earth's.

The host is estimated to be 4.17 billion years old, which is the final useful fact about this system.