Gliese 317 c
Planet· orbits Gliese 317
Gliese 317 c - a cold outer giant (minimum mass ~1.4 Jupiter) on a wide, ~18-year orbit. RV-only: minimum mass, model-estimate size, never imaged.
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Key facts
Minimum mass
2.71 × 10²⁷ kg
1.43 M♃ (455 M⊕)
Year
17.8 Earth years
6,500 Earth days
Distance from Gliese 317
5.04 AU
Science
Physical
- Minimum mass (m·sin i)
- 2.71 × 10²⁷ kg · 1.43 M♃ (455 M⊕)
- Radial-velocity detection measures m·sin i; the true mass depends on the unknown orbital inclination.
- Radius
- Not measured
- No transit — radius is a model estimate for a ~1.4-Jupiter giant; no density is quoted.
Orbital
- Semi-major axis
- 5.04 AU
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Eccentricity
- 0.217
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Orbital period
- 17.80 years
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Perihelion
- 3.95 AU
- Computed from the orbital elements
- Aphelion
- 6.13 AU
- Computed from the orbital elements
- Mean orbital velocity
- 8.44 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- A cold outer gas giant of minimum mass ~1.4 Jupiter; confirmed in 2016 after years of radial-velocity tracking, never imaged.
- Cloud appearance
- Appearance based on ESO/M. Kornmesser'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
- 0.00081 S⊕ · 1/1,234 of the sunlight Earth receives
- Computed from Gliese 317's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 48 K (-225 °C)
- Computed model value for its cold, wide orbit — not measured.
Discovery & history
- Method
- Radial-velocity detection (stellar wobble)
- Name
- Designated 'c' under the IAU convention that letters a star's planets 'b', 'c', 'd'... in the order they are discovered (the star itself is the unwritten 'a').
Confirmed in 2016 as a second, long-period giant after years of continued radial-velocity tracking.
Images
No official imagery available — this object has never been visited and no officially-licensed depiction exists.