Proxima Centauri d

Planet· orbits the Sun

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⊕
Radius: Not measured

Orbital

Semi-major axis: 4,315,899 km
Eccentricity: 0
Inclination: 0.00 °
Orbital period: 5.1 days
Perihelion: 4,315,899 km
Aphelion: 4,315,899 km
Mean orbital velocity: 61.3 km/s

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 Vision mode; Realism shows a plain spectral colour.

Radiation & temperature

Insolation: 1.88 S⊕ · 1.88× the sunlight Earth receives
Equilibrium temperature: 282 K (9 °C)

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

Proxima d — artist's impression, not a photograph (detected only by its radial-velocity signal; never imaged) — ESO / L. Calçada (CC BY 4.0) · Wikimedia Commons

Proxima d orbiting close to its star, with the Alpha Centauri pair in the distance — artist's impression, not a photograph — ESO / L. Calçada (CC BY 4.0) · Wikimedia Commons

Images from open archives · credit shown per image