The HD 209458 system contains 1 exoplanet. It is located 157.54 light years away from the solar system.
| Mass | 1.23 solar masses |
| Radius | 1.19 solar radiae |
| Temperature | 6091 kelvin |
| Stellar Metallicity | 0.01 decimal exponent |
| Age | 3.1 billion years |
At more than 50 Earth masses, HD 209458 b is a gas giant, a planet whose mass is mostly made up of hydrogen and helium, like Jupiter and Saturn.
| Mass | 232.016 Earth masses |
| Density | 0.362 grams per cubic centimeter |
| Radius | 15.581 Earth radiae |
| Semi-major Axis | 0.04707 AU |
| Eccentricity | 0 |
| Orbital Period | 3.525 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | W. M. Keck Observatory |
| Discovery Telescope | 10 m Keck I Telescope |
| Discovery Instrument | HIRES Spectrometer |
| Discovery Date | 2000-01 |
| Reference | Henry et al. 2000 |