Gas giant · HR 8799

HR 8799 b

ExoplanetsDiscovered 2008

Scientific overview

HR 8799 b is a gas giant orbiting HR 8799, completing an orbit every 170000 days, about 135 light-years from Earth. It was discovered in 2008 using the direct imaging.

Host star

HR 8799

Spectral type

A5 V

Temperature

7,205 K

Mass

1.5 M☉

Planetary system — HR 8799 system

View the HR 8799 system (4 known planets).

Planet	Class	Radius (R⊕)	Period (d)	Distance (ly)
HR 8799 eImaging · 2010	Gas giant	13.11	20816	135
HR 8799 dImaging · 2008	Gas giant	13	37000	135
HR 8799 cImaging · 2008	Gas giant	13	69000	135
HR 8799 bImaging · 2008	Gas giant	13	170000	135

Discovery and detection

Detection method

Direct Imaging

Discovery year

2008

Discovered at

Gemini Observatory

Knowledge connections

OrbitsHR 8799
Member of systemHR 8799 system
Discovered by methodDirect Imaging
Discovered atGemini Observatory
Catalogued inNASA Exoplanet Archive

Quick facts

Class: Gas giant
Host star: HR 8799
Discovery method: Direct Imaging
Discovery year: 2008
Orbital period: 170000 d
Semi-major axis: 68 AU
Radius: 13 R⊕
Mass: 2000 M⊕
Density: 5.02 g/cm³ · derived
Equilibrium temp.: 1200 K
Distance: 135 ly

Density is derived from the archive mass and radius via ρ = M / (4⁄3·π·r³); all other values are catalogued measurements.

Derived values

Computed from source-backed inputs via standard formulae — not observations. Every input and constant is traced below.

Bulk density5.02 g/cm³derived
Formula & inputs
Formula: ρ = M / (4⁄3·π·r³) (v1.0.0, impl v1.0.0)
Inputs:
- massEarth = 2000 M⊕ · NASA
- radiusEarth = 13 R⊕ · NASA
Assumptions: M⊕ = 5.972e+24 kg, R⊕ = 6371000 m (IAU 2015 B3 nominal); Assumes a uniform sphere.
Limitations: Withheld above 30 g/cm³ (inconsistent mass/radius inputs).; Archive mass/radius carry no propagated uncertainty here.
Uncertainty: not propagated (inputs carry no catalogued uncertainty)
Computed as of 2026-06-29.

Scientific citations

Real, source-backed references — primary papers first, then datasets and institutional sources. Formatted through the citation engine; nothing is fabricated.

Archive pageHR 8799 b — NASA Exoplanet Archive

NASA Exoplanet Science Institute (Caltech/IPAC)

Cite (APA / BibTeX)

NASA Exoplanet Science Institute (Caltech/IPAC) (n.d.). HR 8799 b — NASA Exoplanet Archive. NASA Exoplanet Science Institute (Caltech/IPAC). https://exoplanetarchive.ipac.caltech.edu/

@misc{cite:exoarchive-exoplanet-hr-8799-b,
  title        = {HR 8799 b — NASA Exoplanet Archive},
  organization = {NASA Exoplanet Science Institute (Caltech/IPAC)},
  year         = {n.d.},
  url          = {https://exoplanetarchive.ipac.caltech.edu/},
  note         = {Confirmed parameters and discovery references for HR 8799 b.}
}

Quality & authority

Partial

Unreviewed

Description: Complete
Source coverage: Partial
Relationship coverage: Complete
Review coverage: None
Citation coverage: None
Image coverage: Not applicable

Data from the NASA Exoplanet Archive. See source quality.