Proxima Centauri d
Planet· orbits Proxima Centauri
Proxima Centauri d — a sub-Earth world with a minimum mass of about a quarter of Earth's, one of the lightest exoplanets ever detected by radial velocity. It circles Proxima Centauri every 5.1 days, closer in than the habitable zone, and has never been imaged.
Open in 3D viewSee Proxima Centauri d in the live, interactive 3D map
Key facts
Minimum mass
1.55 × 10²⁴ kg
0.26 M⊕
Year
5.12 Earth days
Distance from Proxima Centauri
4,315,899 km
Science
Physical
- Minimum mass (m·sin i)
- 1.55 × 10²⁴ kg · 0.26 M⊕
- Radial-velocity detection measures m·sin i; the true mass depends on the unknown orbital inclination.
- Radius
- Not measured
- No transit has been observed — the radius has never been measured; the rendered size (~0.8 Earth radii) is a mass–radius model estimate.
Orbital
- Semi-major axis
- 4,315,899 km
- From the NASA Exoplanet Archive (radial-velocity orbit; the orbital inclination is unknown, so the orbit is shown face-on in the zone plane)
- Eccentricity
- 0
- From the NASA Exoplanet Archive (radial-velocity orbit; the orbital inclination is unknown, so the orbit is shown face-on in the zone plane)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (radial-velocity orbit; the orbital inclination is unknown, so the orbit is shown face-on in the zone plane)
- Orbital period
- 5.1 days
- From the NASA Exoplanet Archive (radial-velocity orbit; the orbital inclination is unknown, so the orbit is shown face-on in the zone plane)
- Perihelion
- 4,315,899 km
- Computed from the orbital elements
- Aphelion
- 4,315,899 km
- Computed from the orbital elements
- Mean orbital velocity
- 61.3 km/s
- Computed from the orbital elements
Atmosphere
- Composition
- Unknown. Proxima d orbits at 0.029 AU — inside the inner edge of the habitable zone — so it runs warmer than Proxima b; no observation constrains an atmosphere either way.
Composition
- Bulk composition
- Unknown. At a minimum mass of ~0.26 Earths it is plausibly rocky, but nothing beyond its orbit and minimum mass has been measured.
- Surface appearance
- Appearance based on ESO/L. Calçada'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
- 1.88 S⊕ · 1.88× the sunlight Earth receives
- Computed from Proxima Centauri's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 282 K (9 °C)
- NASA Exoplanet Archive model value (no atmosphere assumed), computed for Proxima's dim red output — not measured.
Discovery & history
- Discovered
- February 10, 2022
- By
- João Faria et al. (ESO, ESPRESSO/VLT)
- Method
- Radial-velocity detection (stellar wobble)
- Name
- Designated 'd' as the third planet announced around Proxima Centauri (after b, and the disputed candidate c — which remains unconfirmed and is not shown here).
First seen in 2020 as a hint in VLT/ESPRESSO data taken to confirm Proxima b, and established by João Faria's team in work published in February 2022: a radial-velocity signal of roughly 40 cm/s — slower than a crawl — implying a planet of only ~0.26 Earth masses on a 5.1-day orbit. The NASA Exoplanet Archive lists its confirmation in 2025. It ranks among the lightest worlds ever found by the technique.
Images
Images from open archives · credit shown per image