HR 8799 planetary system
HR 8799 is a white main-sequence star of spectral type A5 approximately 135 light-years from Earth (41.24 parsecs). It hosts 4 confirmed exoplanets.
Host star
- Name
- HR 8799
- Spectral type
- A5
- Effective temperature
- 7,400 K
- Mass
- 1.51 M☉ (solar masses)
- Radius
- 1.49 R☉ (solar radii)
- Distance
- 41.24 pc (135 ly)
- Hipparcos catalog
- HIP 114189
Confirmed planets (4)
| Planet | Class | Mass (M⊕) | Radius (R⊕) | Period (d) | Distance (AU) | Eq. temp (K) | Discovered |
|---|---|---|---|---|---|---|---|
| HR 8799 e | Neptune-like | 3178.30 | 13.11 | 20815.60 | 16.4000 | 1,150 | 2010 |
| HR 8799 d | Neptune-like | 3000.00 | 13.00 | 37000.00 | 24.0000 | 1,300 | 2008 |
| HR 8799 c | Neptune-like | 3000.00 | 13.00 | 69000.00 | 38.0000 | 1,200 | 2008 |
| HR 8799 b | Neptune-like | 2000.00 | 13.00 | 170000.00 | 68.0000 | 1,200 | 2008 |
The planets in detail
HR 8799 e is a Neptune-like world with about 13.11 Earth radii and 3178.30 Earth masses. It orbits HR 8799 at 16.4000 AU with a 57.0-Earth-year orbit, and a scorching equilibrium temperature of 1150 K. It was confirmed in 2010 via direct imaging.
HR 8799 d is a Neptune-like world with about 13.00 Earth radii and 3000.00 Earth masses. It orbits HR 8799 at 24.0000 AU with a 101.3-Earth-year orbit, and an extreme equilibrium temperature exceeding 1300 K. Its orbit is notably eccentric (e = 0.60), meaning the distance to its star — and the irradiation it receives — varies substantially over each year. It was confirmed in 2008 via direct imaging.
HR 8799 c is a Neptune-like world with about 13.00 Earth radii and 3000.00 Earth masses. It orbits HR 8799 at 38.0000 AU with a 188.9-Earth-year orbit, and an extreme equilibrium temperature exceeding 1200 K. Its orbit is notably eccentric (e = 0.50), meaning the distance to its star — and the irradiation it receives — varies substantially over each year. It was confirmed in 2008 via direct imaging.
HR 8799 b is a Neptune-like world with about 13.00 Earth radii and 2000.00 Earth masses. It orbits HR 8799 at 68.0000 AU with a 465.4-Earth-year orbit, and an extreme equilibrium temperature exceeding 1200 K. It was confirmed in 2008 via direct imaging.
Discovery
The HR 8799 system was first identified in 2008, with confirmation work continuing through 2010 using direct imaging. Detection facilities: W. M. Keck Observatory, Gemini Observatory.
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 346.8701°, declination 21.1340°. 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.
