The GJ 581 system contains 3 exoplanets. It is located 20.54 light years away from the solar system.
| Mass | 0.31 solar masses |
| Radius | 0.33 solar radiae |
| Temperature | 3396 kelvin |
| Stellar Metallicity | -0.088 decimal exponent |
| Age | 4.3 billion years |
At more than 10 Earth masses, GJ 581 b 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 | 15.800 Earth masses |
| Density | 1.250 grams per cubic centimeter |
| Radius | 4.110 Earth radiae |
| Semi-major Axis | 0.04061 AU |
| Eccentricity | 0 |
| Orbital Period | 5.369 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | La Silla Observatory |
| Discovery Telescope | 3.6 m ESO Telescope |
| Discovery Instrument | HARPS Spectrograph |
| Discovery Date | 2005-12 |
| Reference | Bonfils et al. 2005 |
At more than 10 Earth masses, GJ 581 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 | 5.500 Earth masses |
| Density | 2.800 grams per cubic centimeter |
| Radius | 2.210 Earth radiae |
| Semi-major Axis | 0.0721 AU |
| Eccentricity | 0 |
| Orbital Period | 12.914 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | La Silla Observatory |
| Discovery Telescope | 3.6 m ESO Telescope |
| Discovery Instrument | HARPS Spectrograph |
| Discovery Date | 2007-07 |
| Reference | Udry et al. 2007 |
At 1.685 Earth masses, GJ 581 e 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 | 1.700 Earth masses |
| Density | 5.830 grams per cubic centimeter |
| Radius | 1.170 Earth radiae |
| Semi-major Axis | 0.02815 AU |
| Eccentricity | 0 |
| Orbital Period | 3.149 days |
| Discovery Method | Radial Velocity |
| Discovery Facility | La Silla Observatory |
| Discovery Telescope | 3.6 m ESO Telescope |
| Discovery Instrument | HARPS Spectrograph |
| Discovery Date | 2009-11 |
| Reference | Mayor et al. 2009 |