The 51 Peg system contains 1 exoplanet. It is located 50.43 light years away from the solar system.
| Mass | 1.03 solar masses |
| Radius | 1.18 solar radiae |
| Temperature | 5758 kelvin |
| Stellar Metallicity | 0.18 decimal exponent |
| Age | 10 billion years |
At more than 50 Earth masses, 51 Peg b is a gas giant, a planet whose mass is mostly made up of hydrogen and helium, like Jupiter and Saturn.
| Mass | 146.202 Earth masses |
| Density | 0.275 grams per cubic centimeter |
| Radius | 14.300 Earth radiae |
| Semi-major Axis | 0.0527 AU |
| Eccentricity | 0.013 |
| Orbital Period | 4.231 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | Haute-Provence Observatory |
| Discovery Telescope | 1.93 m Telescope |
| Discovery Instrument | ELODIE Spectrograph |
| Discovery Date | 1995-11 |
| Reference | Mayor & Queloz 1995 |