Kepler-347 and Its Three Worlds

Kepler-347 is a star 4240 light-years away with three known planets. The host is 3.89 billion years old, has 1.05 solar masses, 1.06 solar radii, and a temperature of 5890 K, which is hotter than the Sun's. All three planets were found by transit, the method that detects the slight dimming caused when a planet crosses in front of its star, and repeated dips help establish orbital periods.

Kepler-347 b and Kepler-347 c are both Super-Earths, a size class that reaches 2.5 times Earth's radius. Kepler-347 b has a radius of 1.97 Earth radii - larger than Earth's - and completes an orbit in 12.8 days, the shortest year among the listed planets. Kepler-347 c has a radius of 1.75 Earth radii, the smallest among the listed planets, and an orbital period of 27.3 days, the second-shortest year. Kepler-347 d is Neptune-like, a class reaching 4 times Earth's radius. Its radius of 3.04 Earth radii is the largest among the listed planets and larger than Earth's, and its orbital period of 85.5 days is the longest year among the listed planets.