The Kepler-309 system contains 2 exoplanets. It is located 1776.14 light years away from the solar system.
| Mass | 0.67 solar masses |
| Radius | 0.72 solar radiae |
| Temperature | 4713 kelvin |
| Stellar Metallicity | 0.11 decimal exponent |
| Age | 3.02 billion years |
At 3.056 Earth masses, Kepler-309 b is a so called Super Earth. Super Earths could be terrestrial worlds like Earth, but they could also be ocean worlds or terrestrial worlds wrapped in a substantial atmosphere, in which case some refer to them as Mini Neptunes.
| Mass | 3.050 Earth masses |
| Density | 4.410 grams per cubic centimeter |
| Radius | 1.560 Earth radiae |
| Semi-major Axis | 0.059 AU |
| Eccentricity | 0 |
| Orbital Period | 5.924 days |
| Discovery Method | Transit |
| Discovery Facility | Kepler |
| Discovery Telescope | 0.95 m Kepler Telescope |
| Discovery Instrument | Kepler CCD Array |
| Discovery Date | 2014-03 |
| Reference | Rowe et al. 2014 |
At more than 10 Earth masses, Kepler-309 c 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.
| Mass | 6.850 Earth masses |
| Density | 2.380 grams per cubic centimeter |
| Radius | 2.510 Earth radiae |
| Semi-major Axis | 0.401 AU |
| Eccentricity | 0 |
| Orbital Period | 105.356 days |
| Discovery Method | Transit |
| Discovery Facility | Kepler |
| Discovery Telescope | 0.95 m Kepler Telescope |
| Discovery Instrument | Kepler CCD Array |
| Discovery Date | 2014-03 |
| Reference | Rowe et al. 2014 |