HR 8799 b
Planet· orbits HR 8799
HR 8799 b — the outermost imaged giant (~5-7 Jupiter masses), circling far out at ~68 AU over roughly 460 years. The faintest and easiest to separate from the star, it was a key part of the first family portrait of another planetary system. Size and mass are model estimates, so no density is quoted.
Open in 3D viewSee HR 8799 b in the live, interactive 3D map
Key facts
Mass
1.19 × 10²⁸ kg
6.29 M♃ (2,000 M⊕)
Year
465 Earth years
170,000 Earth days
Distance from HR 8799
68 AU
Science
Physical
- Mass
- 1.19 × 10²⁸ kg · 6.29 M♃ (2,000 M⊕)
- Radius
- Not measured
- Imaged, never transited: size and mass are model estimates from its brightness and age, so no density is quoted.
Orbital
- Semi-major axis
- 68 AU
- From the NASA Exoplanet Archive (direct imaging + orbit fit)
- Eccentricity
- 0.02
- From the NASA Exoplanet Archive (direct imaging + orbit fit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (direct imaging + orbit fit)
- Orbital period
- 465.43 years
- From the NASA Exoplanet Archive (direct imaging + orbit fit)
- Perihelion
- 66.6 AU
- Computed from the orbital elements
- Aphelion
- 69.4 AU
- Computed from the orbital elements
- Mean orbital velocity
- 4.35 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- A young gas giant of ~5–7 Jupiter masses circling far out at ~68 AU, the faintest and outermost of HR 8799's four imaged worlds. Self-luminous at ~1,100 K; hydrogen/helium.
- Cloud appearance
- Appearance based on NASA/JPL-Caltech's artist's concept. No spacecraft has imaged this world, so its real appearance is unknown — The banded clouds shown are a representation of its class, shown only in Visual mode; Realism shows a plain spectral colour.
Radiation & temperature
- Insolation
- 0.00123 S⊕ · 1/814 of the sunlight Earth receives
- Computed from HR 8799's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
Discovery & history
- Discovered
- November 13, 2008
- Method
- Directly imaged
- Name
- Designated 'b' under the IAU planet-lettering convention; no IAU proper name has been assigned.
One of the three planets directly imaged around HR 8799 in 2008 — the outermost of the first multi-planet system ever photographed.
Images
Directly imaged only as a point of light beside HR 8799 — see the system view for the real Keck time-lapse and Hubble images that show all four planets. No telescope has resolved this planet's disk or surface.