The HD 20781 system contains 5 exoplanets. It is located 117.32 light years away from the solar system.
| Mass | 0.7 solar masses |
| Radius | 0.83 solar radiae |
| Temperature | 5256 kelvin |
| Stellar Metallicity | -0.11 decimal exponent |
| Age | - billion years |
At 1.940 Earth masses, HD 20781 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 | 1.930 Earth masses |
| Density | 5.990 grams per cubic centimeter |
| Radius | 1.210 Earth radiae |
| Semi-major Axis | 0.0529 AU |
| Eccentricity | 0.1 |
| Orbital Period | 5.314 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | La Silla Observatory |
| Discovery Telescope | 3.6 m ESO Telescope |
| Discovery Instrument | HARPS Spectrograph |
| Discovery Date | 2019-02 |
| Reference | Udry et al. 2019 |
At more than 10 Earth masses, HD 20781 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 | 5.330 Earth masses |
| Density | 2.870 grams per cubic centimeter |
| Radius | 2.170 Earth radiae |
| Semi-major Axis | 0.1004 AU |
| Eccentricity | 0.09 |
| Orbital Period | 13.890 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | La Silla Observatory |
| Discovery Telescope | 3.6 m ESO Telescope |
| Discovery Instrument | HARPS Spectrograph |
| Discovery Date | 2019-02 |
| Reference | Udry et al. 2019 |
At more than 10 Earth masses, HD 20781 d 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 | 10.610 Earth masses |
| Density | 1.700 grams per cubic centimeter |
| Radius | 3.250 Earth radiae |
| Semi-major Axis | 0.1647 AU |
| Eccentricity | 0.11 |
| Orbital Period | 29.158 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | La Silla Observatory |
| Discovery Telescope | 3.6 m ESO Telescope |
| Discovery Instrument | HARPS Spectrograph |
| Discovery Date | 2019-02 |
| Reference | Udry et al. 2019 |
At more than 10 Earth masses, HD 20781 e 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 | 14.030 Earth masses |
| Density | 1.370 grams per cubic centimeter |
| Radius | 3.830 Earth radiae |
| Semi-major Axis | 0.3374 AU |
| Eccentricity | 0.06 |
| Orbital Period | 85.507 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | La Silla Observatory |
| Discovery Telescope | 3.6 m ESO Telescope |
| Discovery Instrument | HARPS Spectrograph |
| Discovery Date | 2019-02 |
| Reference | Udry et al. 2019 |