Proxima Centauri (Alpha Centauri C)
Coordinates, Gaia DR3 parallax (768.07 mas, 4.2465 ly), magnitude 11.13, flare activity, and planetary system guide for Proxima Centauri.
Provenance-Backed Scientific Measurements
Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.
| Parameter | Value | Uncertainty | Method & Epoch | Quality Status | Source Archive |
|---|---|---|---|---|---|
| Trigonometric parallax (Gaia DR3) | 768.0665 mas | ± 0.0499 mas | Gaia DR3 five-parameter space astrometry (J2016.0) | definitive | ESA Gaia Archive — Data Release 3 |
| Distance in light-years | 4.2465 ly | ± 0.0003 ly | Derived from Gaia DR3 parallax (1.30197 ± 0.00008 pc) (J2016.0) | definitive | ESA Gaia Archive — Data Release 3 |
| Quiescent visual magnitude (V) | 11.13 mag | ± 0.05 mag | Optical CCD photometry (flares brighten V by 1–4 mag) | definitive | SIMBAD Astronomical Database (CDS) |
| Stellar mass | 0.1221 M☉ | ± 0.0022 M☉ | VLTI interferometric radius + empirical M-dwarf mass-luminosity relation | high-confidence | SIMBAD Astronomical Database (CDS) |
| Linear radius | 0.1542 R☉ | ± 0.0045 R☉ | VLTI/PIONIER optical interferometry (angular diameter 1.030 ± 0.030 mas) | definitive | SIMBAD Astronomical Database (CDS) |
| Effective temperature | 3042 K | ± 117 K | Bolometric flux + interferometric angular diameter | high-confidence | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Proxima Centauri (Nearest Star to Sun) at RA 14h 29m 42.95s, Dec -62° 40′ 46.1″ within Centaurus, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.
Astrophysical Context & Structure
Proxima Centauri (Alpha Centauri C, V645 Centauri) is the nearest individual star to our Sun, lying at a Gaia DR3 distance of 1.30197 ± 0.00008 parsecs (4.2465 ± 0.0003 light-years) in the southern constellation Centaurus. Discovered photographic-plate blinking by Scottish astronomer Robert Innes at the Union Observatory in Johannesburg in 1915, Proxima sits 2.18° (~13,000 AU) southwest of the bright Alpha Centauri AB binary and completes a gravitationally bound orbit around AB every ~550,000 years.
With a mass of just 0.122 solar masses (128 Jupiter masses) and a surface temperature of 3,042 K, Proxima is a fully convective M5.5 Ve red dwarf whose total bolometric luminosity is only 0.155% of the Sun's—and in visible light just 0.005% of the Sun's output. Because convective currents transport helium ash evenly throughout its interior without forming an inert core, Proxima will fuse hydrogen steadily for roughly 4 trillion years.
High-precision ESO ESPRESSO and HARPS radial-velocity campaigns have confirmed at least two low-mass planets orbiting Proxima: the habitable-zone Earth-mass planet Proxima Centauri b (11.186-day period) and the ultra-short-period sub-Earth Proxima d (5.12-day period), subjected to intense X-ray and extreme-UV magnetic flares.
Practical Visual Observing Guide
- Despite being the closest star to the Solar System, Proxima Centauri shines at a dim magnitude 11.13—roughly 100 times fainter than the naked-eye limit—requiring at least an 80–100 mm telescope and a detailed 15-arcminute finder chart.
- Located at declination −62°41′, it is only accessible to observers south of +27°N latitude, lying 2.2° southwest of Alpha Centauri (Rigil Kentaurus).
- Because its total proper motion is huge (3.85 arcseconds per year westward), Proxima noticeably shifts position against background 12th-magnitude Milky Way field stars over just a few years.
Catalog Cross-Identifications & Aliases
Common Aliases: α Centauri C · V645 Centauri · HIP 70890 · GJ 551
| Catalog Authority | Identifier |
|---|---|
| GAIADR3 | 5853498713190525696 |
| HIP | HIP 70890 |
| SIMBAD | * alf Cen C |
| WIKIDATA | Q14266 |
Related Objects, Comparisons & Guides
Proxima Centauri b (Nearest Exoplanet)
Coordinates, ESPRESSO minimum mass (1.07 M⊕), 11.186-day habitable-zone orbit at 0.04856 AU, and stellar flare environment of Proxima Centauri b.
Sirius (Alpha Canis Majoris Binary)
Coordinates, Hipparcos parallax (379.21 mas, 8.60 ly), magnitude −1.46, Sirius B white dwarf orbit, and observing guide for Sirius.
Tau Ceti (HD 10700 Nearby Solar Analog)
Coordinates, Gaia DR3 parallax (273.81 mas, 11.91 ly), magnitude 3.50, debris disk, and observing guide for G8V star Tau Ceti.
Omega Centauri (NGC 5139 Cluster)
Coordinates, Gaia DR3 distance (5.43 kpc), magnitude 3.68, and multi-population core data for Omega Centauri (NGC 5139) in Centaurus.
TRAPPIST-1 e vs Proxima Centauri b Comparison
Compare the two benchmark temperate M-dwarf rocky exoplanets TRAPPIST-1 e and Proxima Centauri b: detection method, mass, radius, and habitability.
Trigonometric Parallax, Parsecs & Gaia DR3
How trigonometric parallax (d_pc = 1 / p_arcsec), the distance modulus equation, Hipparcos, and Gaia DR3 microarcsecond astrometry measure cosmic distances.
Proper Motion, Radial Velocity & Redshift
How astronomers combine tangential proper motion (mas/yr), Doppler radial velocity (km/s), and cosmological redshift (z) to reconstruct 3D space motion.
Apparent vs Absolute Magnitude Explained
Understand the logarithmic Pogson astronomical magnitude scale, apparent visual magnitude (m), absolute magnitude (M at 10 parsecs), and bolometric corrections.
Bright, Multiple & Variable Stars Catalog
Cross-reference catalog of solar-neighborhood and navigation stars across Bayer, Henry Draper (HD), Hipparcos (HIP), WDS, and Gaia DR3 designations.
Confirmed Exoplanets & Host Systems Catalog
Curated NASA Exoplanet Archive reference catalog of benchmark exoplanets: Proxima Centauri b, TRAPPIST-1 e, 51 Pegasi b, HD 209458 b, K2-18 b, and WASP-39 b.
Scientific Sources & Dataset Provenance
- ESA Gaia Archive — Data Release 3 (DR3 (2022-06-13)): Gaia Collaboration, Vallenari, A., et al. 2023, A&A, 674, A1 (Gaia Data Release 3) — European Space Agency / Gaia DPAC
- NASA Exoplanet Archive (2026-10-01 snapshot): Akeson, R. L., et al. 2013, PASP, 125, 989; NASA Exoplanet Archive (IPAC/Caltech) — NASA Exoplanet Science Institute (NExScI / Caltech / IPAC)
- SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg