Kepler-177: A Distant Star With Two Giant Planets

Kepler-177 is a star located 4,680 light-years away. It has a mass of 1 solar mass and a radius of 0.98 solar radii, making it very similar to the Sun in both respects. Its temperature is 5,780 K, and its age is 4.37 billion years. Two planets are known to orbit this host, and the system has one star.

Kepler-177 b was discovered by transit in 2013. It is classified as Neptune-like, with a radius of 3.5 Earth radii. Its mass is 5.84 Earth masses, and its mean density is 0.751 g/cm³, 0.136 times Earth's. It completes one orbit in 36.9 days, the shortest orbital period among the listed planets.

Kepler-177 c was also discovered by transit in 2013. It is classified as Jupiter-like, with a radius of 8.73 Earth radii. Its mass is 14.7 Earth masses, and its mean density is 0.122 g/cm³, 0.0221 times Earth's. Its orbital period is 49.4 days, the longest among the listed planets.

Both planets have reported radius and mass estimates larger than Earth's. Among the listed planets, Kepler-177 b has the smallest radius and the smallest reported mass, while Kepler-177 c has the largest radius and the largest reported mass. 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.