Lalande 21185 b
Planet· orbits Lalande 21185
Lalande 21185 b — a warm super-Earth (minimum mass ~2.7 Earth) on a 12.9-day orbit, the inner of the star's two confirmed planets. Never imaged; its true size and surface are unknown.
Open in 3D viewSee Lalande 21185 b in the live, interactive 3D map
Key facts
Minimum mass
1.61 × 10²⁵ kg
2.69 M⊕
Year
12.94 Earth days
Distance from Lalande 21185
11,788,312 km
Science
Physical
- Minimum mass (m·sin i)
- 1.61 × 10²⁵ kg · 2.69 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 for a rocky world of this minimum mass; true size unknown.
Orbital
- Semi-major axis
- 11,788,312 km
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Eccentricity
- 0.063
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Orbital period
- 12.9 days
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Perihelion
- 11,045,649 km
- Computed from the orbital elements
- Aphelion
- 12,530,976 km
- Computed from the orbital elements
- Mean orbital velocity
- 66.3 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- Presumed rocky (minimum mass ~2.7 Earth), but never imaged — surface unknown.
- Surface appearance
- Appearance based on ESO/M. Kornmesser's artist's concept. No spacecraft has imaged this world, so its real appearance is unknown — The surface shown is an artistic representation, shown only in Visual mode; Realism shows a plain spectral colour.
Radiation & temperature
- Insolation
- 3.14 S⊕ · 3.14× the sunlight Earth receives
- Computed from Lalande 21185's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 350 K (77 °C)
- Computed model value (no atmosphere assumed) — not measured.
Discovery & history
- Method
- Radial-velocity detection (stellar wobble)
- Name
- Designated 'b' as the first planet found around its star, following the IAU convention of lettering planets in discovery order from 'b'.
Confirmed in 2019 from years of radial-velocity monitoring of Lalande 21185 — a small periodic tug in the star's spectrum betraying a world several times Earth's mass.
Images
No official imagery available — this object has never been visited and no officially-licensed depiction exists.