GJ 876 planetary system
GJ 876 is a cool red dwarf of spectral type M2.5V approximately 15.2 light-years from Earth (4.68 parsecs). It hosts 4 confirmed exoplanets.
Host star
- Name
- GJ 876
- Spectral type
- M2.5V
- Effective temperature
- 3,294 K
- Mass
- 0.32 M☉ (solar masses)
- Radius
- 0.30 R☉ (solar radii)
- Distance
- 4.68 pc (15.2 ly)
- Hipparcos catalog
- HIP 113020
Confirmed planets (4)
| Planet | Class | Mass (M⊕) | Radius (R⊕) | Period (d) | Distance (AU) | Eq. temp (K) | Discovered |
|---|---|---|---|---|---|---|---|
| GJ 876 d | Mini-Neptune | 6.83 | 2.51 | 1.94 | 0.0208 | — | 2005 |
| GJ 876 c | Neptune-like | 226.98 | 14.00 | 30.09 | 0.1296 | — | 2000 |
| GJ 876 b | Neptune-like | 723.22 | 13.30 | 61.12 | 0.2083 | — | 1998 |
| GJ 876 e | Mini-Neptune | 14.60 | 3.92 | 124.26 | 0.3343 | — | 2010 |
The planets in detail
GJ 876 d is a Mini-Neptune with about 2.51 Earth radii and 6.83 Earth masses. It orbits GJ 876 at 0.0208 AU with a 1.9-day year, and no published equilibrium temperature. Its orbit is notably eccentric (e = 0.21), meaning the distance to its star — and the irradiation it receives — varies substantially over each year. It was confirmed in 2005 via radial velocity (Doppler) measurements.
GJ 876 c is a Neptune-like world with about 14.00 Earth radii and 226.98 Earth masses. It orbits GJ 876 at 0.1296 AU with a 30.1-day year, and no published equilibrium temperature. Its orbit is notably eccentric (e = 0.26), meaning the distance to its star — and the irradiation it receives — varies substantially over each year. It was confirmed in 2000 via radial velocity (Doppler) measurements.
GJ 876 b is a Neptune-like world with about 13.30 Earth radii and 723.22 Earth masses. It orbits GJ 876 at 0.2083 AU with a 61.1-day year, and no published equilibrium temperature. It was confirmed in 1998 via radial velocity (Doppler) measurements.
GJ 876 e is a Mini-Neptune with about 3.92 Earth radii and 14.60 Earth masses. It orbits GJ 876 at 0.3343 AU with a 124-day year, and no published equilibrium temperature. It was confirmed in 2010 via radial velocity (Doppler) measurements.
Discovery
The GJ 876 system was first identified in 1998, with confirmation work continuing through 2010 using radial velocity (Doppler) measurements. Detection facilities: W. M. Keck Observatory, Multiple Observatories.
Observing from Earth
Exoplanets cannot be resolved visually with amateur telescopes — the host star's glare is overwhelming and even space-based direct imaging requires sophisticated coronagraphs. What you can observe is the host star itself at right ascension 343.3240°, declination -14.2666°. Use the 3D orrery above to inspect orbital geometry, planetary scale, and the habitable-zone overlay — the orbits are computed from the published Keplerian elements and animate at user-controlled time rates.
