Kepler-305 and Its Four Planets

Kepler-305 is a star located 2830 light-years away, and four planets have been identified orbiting it. The host star is estimated to be 4.37 billion years old, with a mass of 0.85 solar masses and a radius of 0.79 solar radii. Its reported temperature is 5120 K. Each of these stellar measurements is smaller or cooler than the corresponding value for the Sun.

The planets were all found through the transit method, in which a planet passes in front of its star from our viewpoint and causes a small dip in observed brightness; repeated dips help establish orbital periods. Kepler-305 b, Kepler-305 c, and Kepler-305 d are Neptune-like planets, while Kepler-305 e is a Super-Earth. Kepler-305 b has a mass of 10.5 Earth masses, a radius of 3.6 Earth radii, and an orbital period of 5.49 days. Kepler-305 c has a mass of 6 Earth masses, a radius of 3.3 Earth radii, and an orbital period of 8.29 days. Kepler-305 d has a mass of 6.2 Earth masses, a radius of 2.76 Earth radii, and an orbital period of 16.7 days. Kepler-305 e has a radius of 1.79 Earth radii and an orbital period of 3.21 days.

Among the listed planets, Kepler-305 e has the shortest year, at 3.21 days, and the smallest radius, at 1.79 Earth radii. Kepler-305 b has the second-shortest year, at 5.49 days, and the largest radius, at 3.6 Earth radii. Kepler-305 c has the second-longest year, at 8.29 days, and the second-largest radius, at 3.3 Earth radii. Kepler-305 d has the longest year, at 16.7 days, and the second-smallest radius, at 2.76 Earth radii. The reported radius and mass estimates for Kepler-305 b, Kepler-305 c, and Kepler-305 d are each larger than Earth's, and Kepler-305 e's reported radius estimate is also larger than Earth's. Kepler-305 b's mean density is 1.24 g/cm³, 0.225 times Earth's; Kepler-305 c's is 0.92 g/cm³, 0.167 times Earth's; and Kepler-305 d's is 1.62 g/cm³, 0.295 times Earth's.