Barnard's Star c
Planet· orbits Barnard's Star
Barnard's Star c — a sub-Earth world (minimum mass ~0.34 Earth) on a 4.1-day orbit, one of a compact family of four. Too hot for liquid water; never imaged.
Open in 3D viewSee Barnard's Star c in the live, interactive 3D map
Key facts
Minimum mass
2.00 × 10²⁴ kg
0.335 M⊕
Year
4.12 Earth days
Distance from Barnard's Star
4,098,982 km
Science
Physical
- Minimum mass (m·sin i)
- 2.00 × 10²⁴ kg · 0.335 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 rocky world of this minimum mass; true size unknown.
Orbital
- Semi-major axis
- 4,098,982 km
- From the NASA Exoplanet Archive (ESO/ESPRESSO radial-velocity orbit)
- Eccentricity
- 0.08
- From the NASA Exoplanet Archive (ESO/ESPRESSO radial-velocity orbit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (ESO/ESPRESSO radial-velocity orbit)
- Orbital period
- 4.1 days
- From the NASA Exoplanet Archive (ESO/ESPRESSO radial-velocity orbit)
- Perihelion
- 3,771,063 km
- Computed from the orbital elements
- Aphelion
- 4,426,900 km
- Computed from the orbital elements
- Mean orbital velocity
- 72.3 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- Presumed rocky (minimum mass ~0.34 Earth); never imaged.
- 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
- 4.66 S⊕ · 4.66× the sunlight Earth receives
- Computed from Barnard's Star's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 400 K (127 °C)
- Computed model value (no atmosphere assumed) — not measured.
Discovery & history
- Method
- Radial-velocity detection (stellar wobble)
- Name
- Designated 'c' as the second planet found around Barnard's Star, following the IAU convention of lettering planets in discovery order starting at 'b'.
Established in 2025 as ESO's ESPRESSO revealed that Barnard's Star hosts not one planet but a compact family of four sub-Earth worlds, all orbiting closer in than Mercury.
Images
Never imaged — this world is known only from the tiny gravitational tug it exerts on its star (radial velocity). An artist's impression of the whole system is on the system view; the planet's own appearance is unknown.