Lalande 21185 c
Planet· orbits Lalande 21185
Lalande 21185 c — a cold, more massive world (minimum mass ~13.6 Earth) on a wide ~8-year orbit, far from its faint star. Likely an icy super-Earth or small ice giant; never imaged, so its nature is uncertain.
Open in 3D viewSee Lalande 21185 c in the live, interactive 3D map
Key facts
Minimum mass
8.12 × 10²⁵ kg
13.6 M⊕
Year
8.07 Earth years
2,946 Earth days
Distance from Lalande 21185
2.94 AU
Science
Physical
- Minimum mass (m·sin i)
- 8.12 × 10²⁵ kg · 13.6 M⊕
- Radial-velocity detection measures m·sin i; the true mass depends on the unknown orbital inclination.
- Radius
- Not measured
- No transit — the radius is a model estimate; true size and nature unknown.
Orbital
- Semi-major axis
- 2.94 AU
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Eccentricity
- 0.132
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Orbital period
- 8.07 years
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Perihelion
- 2.55 AU
- Computed from the orbital elements
- Aphelion
- 3.33 AU
- Computed from the orbital elements
- Mean orbital velocity
- 10.9 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- Cold and fairly massive — likely an icy super-Earth or small ice giant (minimum mass ~13.6 Earth); 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
- 0.00226 S⊕ · 1/443 of the sunlight Earth receives
- Computed from Lalande 21185's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 63 K (-210 °C)
- Computed model value for its cold, wide orbit — not measured.
Discovery & history
- Method
- Radial-velocity detection (stellar wobble)
- Name
- Designated 'c' as the second planet found around its star, following the IAU convention of lettering planets in discovery order from 'b'.
Established in 2021 as longer radial-velocity baselines revealed a second, slow signal — a distant companion taking about eight years to circle the star.
Images
No official imagery available — this object has never been visited and no officially-licensed depiction exists.