Kepler-107: A Star and Its Four Small Worlds

Kepler-107 is a star located 1720 light-years away, and four planets have been found orbiting it. The star is estimated to be 4.29 billion years old, with a mass of 1.24 solar masses and a radius of 1.45 solar radii. Its reported temperature of 5850 K is hotter than the Sun's, and both its mass and radius estimates are larger than the Sun's.

All four planets were discovered by the transit method in 2014, in which a planet passing in front of its star from our viewpoint causes a small dip in observed brightness. Kepler-107 b is a Super-Earth with a radius of 1.54 Earth radii and a mass of 3.8 Earth masses. It has the shortest year among the listed planets, at 3.18 days, and its mean density is 5.78 g/cm³, 1.05 times Earth's. Kepler-107 c is also a Super-Earth, with a radius of 1.6 Earth radii and a mass of 10 Earth masses; its year of 4.9 days is the second-shortest among the listed planets, and its mean density is 13.5 g/cm³, 2.46 times Earth's.

Kepler-107 d is a Sub-Earth, smaller than Earth at 0.86 Earth radii, which is the smallest radius among the listed planets. It has a reported upper limit of 7.7 Earth masses, and its year of 7.96 days is the second-longest among the listed planets. Kepler-107 e is Neptune-like, with a radius of 2.9 Earth radii - the largest among the listed planets - and a mass of 14.1 Earth masses. Its year of 14.7 days is the longest among the listed planets, and its mean density is 3.18 g/cm³, 0.576 times Earth's.