The HD 128311 system contains 2 exoplanets. It is located 53.26 light years away from the solar system.
| Mass | 0.83 solar masses |
| Radius | 0.76 solar radiae |
| Temperature | 4965 kelvin |
| Stellar Metallicity | 0.08 decimal exponent |
| Age | 0.96 billion years |
At more than 50 Earth masses, HD 128311 b is a gas giant, a planet whose mass is mostly made up of hydrogen and helium, like Jupiter and Saturn.
| Mass | 562.241 Earth masses |
| Density | 1.260 grams per cubic centimeter |
| Radius | 13.500 Earth radiae |
| Semi-major Axis | 1.084 AU |
| Eccentricity | 0.303 |
| Orbital Period | 453.019 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | W. M. Keck Observatory |
| Discovery Telescope | 10 m Keck I Telescope |
| Discovery Instrument | HIRES Spectrometer |
| Discovery Date | 2003-01 |
| Reference | Butler et al. 2003 |
At more than 50 Earth masses, HD 128311 c is a gas giant, a planet whose mass is mostly made up of hydrogen and helium, like Jupiter and Saturn.
| Mass | 1204.258 Earth masses |
| Density | 3.010 grams per cubic centimeter |
| Radius | 13.000 Earth radiae |
| Semi-major Axis | 1.74 AU |
| Eccentricity | 0.159 |
| Orbital Period | 921.538 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | W. M. Keck Observatory |
| Discovery Telescope | 10 m Keck I Telescope |
| Discovery Instrument | HIRES Spectrometer |
| Discovery Date | 2005-10 |
| Reference | Vogt et al. 2005 |