Kepler-104: A Neptune-Class Trio in a Distant Star System

Kepler-104 is a star located 1310 light-years away. It is 3.72 billion years old, holds 1.01 solar masses, spans 1.03 solar radii, and has a temperature of 6030 K, which is hotter than the Sun's. Three planets orbit this host: all were discovered by transit in 2014, and all are Neptune-like, a size class reaching up to four times Earth's radius. 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.

Kepler-104 b completes an orbit in 11.4 days and has a radius of 3.1 Earth radii. Kepler-104 c orbits in 23.7 days with a radius of 3.13 Earth radii. Kepler-104 d takes 51.8 days to circle the star and has a radius of 3.58 Earth radii. Each planet's reported radius estimate is larger than Earth's.

Among the listed planets, Kepler-104 b has the shortest year and the smallest radius by reported estimates. Kepler-104 c has the second-shortest year and the second-smallest radius. Kepler-104 d has the longest year and the largest radius by reported estimates, at 51.8 days and 3.58 Earth radii.