The star
The star
HR 8799
- Type
- A5 V
- Surface
- ≈ 7,205 K
- Size
- 1.49 × the Sun
- Mass
- 1.50 × the Sun
- Brightness
- 4.92 × the Sun
- Habitable zone
- 2.11–3.7 AU
The planets
HR 8799
HR 8799 e
- Year
- 57.0 years
- Distance from star
- 16.4 AU
- Mass
- 10 Jupiters
- Size
- 13 × Earth
- Temperature
- ≈ 1150 K (+877 °C)
- Found
- 2010, imaging (W. M. Keck Observatory)
HR 8799
HR 8799 d
- Year
- 101.3 years
- Distance from star
- 24 AU
- Mass
- 9.4 Jupiters
- Size
- 13 × Earth
- Temperature
- ≈ 1300 K (+1027 °C)
- Found
- 2008, imaging (W. M. Keck Observatory)
HR 8799
HR 8799 c
- Year
- 188.9 years
- Distance from star
- 38 AU
- Mass
- 9.4 Jupiters
- Size
- 13 × Earth
- Temperature
- ≈ 1200 K (+927 °C)
- Found
- 2008, imaging (Gemini Observatory)
HR 8799
HR 8799 b
- Year
- 465.4 years
- Distance from star
- 68 AU
- Mass
- 6.3 Jupiters
- Size
- 13 × Earth
- Temperature
- ≈ 1200 K (+927 °C)
- Found
- 2008, imaging (Gemini Observatory)
Masses found by the wobble method are minimums, because the orbit's tilt is unknown. Temperatures are equilibrium estimates for a bare planet, before any atmosphere.
How we know
A direct picture
The star's glare is blocked or subtracted, leaving the planet's own faint light as a dot that moves along its orbit over the years.
Sources
- Planet and star parameters: NASA Exoplanet Archive, Planetary Systems Composite Parameters, retrieved 1 Nov 2026. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with NASA under the Exoplanet Exploration Program.
- Position: HYG Database v4.1 (CC BY-SA 4.0).
- Habitable zone: a simple estimate from the star's brightness (√L × 0.95 to 1.67 AU), shown as a guide.