Proxima Centauri b
Artist's conception of Proxima Centauri b as a terrestrial exoplanet, with Proxima Centauri and the Alpha Centauri system visible in the background. The actual appearance and composition of the exoplanet beyond this data is currently unknown. | |
| Discovery[1] | |
|---|---|
| Discovered by | Anglada-Escudé et al. |
| Discovery site | European Southern Observatory |
| Discovery date | 24 August 2016 |
Detection method | Doppler spectroscopy |
| Orbital characteristics[2] | |
| 0.04848±0.00029 AU | |
| Eccentricity | low[a] |
| 11.18465±0.00053 d | |
| Semi-amplitude | 1.226±0.062 m/s |
| Star | Proxima Centauri |
| Physical characteristics | |
Mean radius | 0.94–1.4 R🜨[5][b] |
| Mass | ≥1.055±0.055 M🜨[2] |
| Temperature | Teq: 234 K (−39 °C; −38 °F)[6] |
Proxima Centauri b is an exoplanet orbiting within the habitable zone of the red dwarf star Proxima Centauri in the constellation Centaurus. It can also be referred to as Proxima b,[7] or Alpha Centauri Cb. The host star is the closest star to the Sun, at a distance of about 4.2 light-years (1.3 parsecs) from Earth, and is part of the larger triple star system Alpha Centauri. Proxima b and Proxima d, along with the currently disputed Proxima c, are the closest known exoplanets to the Solar System.
Proxima Centauri b orbits its parent star at a distance of about 0.04848 AU (7.253 million km; 4.506 million mi) with an orbital period of approximately 11.2 Earth days. Its other properties are only poorly understood as of 2025, but it is probably a terrestrial planet with a minimum mass of 1.06 M🜨 and a slightly larger radius than that of Earth. The planet orbits within the habitable zone of its parent star; but it is not known whether it has an atmosphere, which would impact the habitability probabilities. Proxima Centauri is a flare star with intense emission of electromagnetic radiation that could strip an atmosphere off the planet.
Announced on 24 August 2016 by the European Southern Observatory (ESO), Proxima Centauri b was confirmed via several years of Doppler spectroscopy measurements of its parent star. The detection of Proxima Centauri b was a major discovery in planetology,[8] and has drawn interest to the Alpha Centauri star system as a whole.[9] As of 2023, Proxima Centauri b is believed to be the best-known exoplanet to the general public.[10] The exoplanet's proximity to Earth offers an opportunity for robotic space exploration.
- ^ Anglada-Escudé et al. 2016.
- ^ a b c Suárez Mascareño et al. 2025, p. 14.
- ^ Suárez Mascareño et al. 2025, p. 15.
- ^ Faria et al. 2022.
- ^ Brugger et al. 2016, p. 1.
- ^ Anglada-Escudé et al. 2016, p. 438.
- ^ Turbet et al. 2016, p. 1.
- ^ Mascareño et al. 2020, p. 1.
- ^ Quarles & Lissauer 2018, p. 1.
- ^ Mieli, Valli & Maccone 2023, p. 435.
Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).