The KELT-21 system contains 1 exoplanet. It is located 1535.80 light years away from the solar system.
| Mass | 1.46 solar masses |
| Radius | 1.64 solar radiae |
| Temperature | 7598 kelvin |
| Stellar Metallicity | -0.405 decimal exponent |
| Age | 1.6 billion years |
At more than 50 Earth masses, KELT-21 b is a gas giant, a planet whose mass is mostly made up of hydrogen and helium, like Jupiter and Saturn.
| Mass | 1242.715 Earth masses |
| Density | 1.240 grams per cubic centimeter |
| Radius | 17.777 Earth radiae |
| Semi-major Axis | 0.05224 AU |
| Eccentricity | 0 |
| Orbital Period | 3.613 days |
| Discovery Method | Transit |
| Discovery Facility | KELT-North |
| Discovery Telescope | Mamiya 645 80mm f/1.9 |
| Discovery Instrument | Apogee 4K CCD Sensor |
| Discovery Date | 2018-02 |
| Reference | Johnson et al. 2018 |