The Kepler-117 Exoplanetary System
Kepler-117 is a star with 1.13 times the mass of the Sun, and 1.61 times its radius. It is located 4664.03 light years away from the solar system and is estimated to be 5.3 billion years old, as compared to the Sun which is roughly 4.6 billion years old.
Kepler-117 is known to have 2 exoplanets in orbit around it.
Kepler-117 b was discovered by the Kepler observatory using the transit method. Its discovery was announced in 2014-03. Its semi-major axis is 0.14 astronomical units, as compared to Earth's which is 1 astronomical unit. It takes 18.80 Earth days to complete an orbit around its host star, Kepler-117.
Its eccentricity, the extent to which the shape of the exoplanet's orbit departs from a perfect circle (Earth's is 0.0167, which is why the shape of Earth's orbit is circular rather than oval in appearance), is 0.0493, which means that when Kepler-117 b is at is at its closest point to its host star, 0.14 astronomical units separates the two, and when it is at its farthest point, this number is 0.15. In the case of Earth, these numbers are 0.9832899 and 1.0167103 respectively.
The mass of Kepler-117 b is 29.87 times the mass of Earth. The radius of Kepler-117 b is 8.059 that of Earth. At more than 10 Earth masses, Kepler-117 b is an ice giant, a planet that is made up mostly of volatiles like water, amonia and methane, and enveloped by a dense hydrogen and helium atmosphere, much like Uranus and Neptune in our solar system.