Alpha Centauri
Alpha Centauri AB (left) forms a triple star system with Proxima Centauri (below, south of, α Centauri AB). (See labelled version) | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| α Centauri A (Rigil Kentaurus) | |
| Right ascension | 14h 39m 36.49400s[1] |
| Declination | −60° 50′ 02.3737″[1] |
| Apparent magnitude (V) | +0.01[2] |
| α Centauri B (Toliman) | |
| Right ascension | 14h 39m 35.06311s[1] |
| Declination | −60° 50′ 15.0992″[1] |
| Apparent magnitude (V) | +1.33[2] |
| Characteristics | |
| A | |
| Spectral type | G2V[3] |
| B−V colour index | +0.71[2] |
| B | |
| Spectral type | K1V[3] |
| B−V colour index | +0.88[2] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −21.4±0.76[4] km/s |
| Proper motion (μ) | RA: −3679.25[1] mas/yr Dec.: +473.67[1] mas/yr |
| Parallax (π) | 750.81±0.38 mas[5] |
| Distance | 4.344 ± 0.002 ly (1.3319 ± 0.0007 pc) |
| Absolute magnitude (MV) | 4.38[6] |
| B | |
| Radial velocity (Rv) | −18.6±1.64[4] km/s |
| Proper motion (μ) | RA: −3614.39[1] mas/yr Dec.: +802.98[1] mas/yr |
| Parallax (π) | 750.81±0.38 mas[5] |
| Distance | 4.344 ± 0.002 ly (1.3319 ± 0.0007 pc) |
| Absolute magnitude (MV) | 5.71[6] |
| Orbit[5] | |
| Primary | A |
| Companion | B |
| Period (P) | 79.762±0.019 yr |
| Semi-major axis (a) | 17.493±0.0096″ |
| Eccentricity (e) | 0.51947±0.00015 |
| Inclination (i) | 79.243±0.0089° |
| Longitude of the node (Ω) | 205.073±0.025° |
| Periastron epoch (T) | 1875.66±0.012 |
| Argument of periastron (ω) (secondary) | 231.519±0.027° |
| Details | |
| α Centauri A | |
| Mass | 1.0788±0.0029[5] M☉ |
| Radius | 1.2175±0.0055[5] R☉ |
| Luminosity | 1.5059±0.0019[5] L☉ |
| Surface gravity (log g) | 4.30[7] cgs |
| Temperature | 5,804±13[8] K |
| Metallicity [Fe/H] | 0.20±0.01[8] dex |
| Rotation | 28.3±0.5 d[9] |
| Rotational velocity (v sin i) | 2.7±0.7[10] km/s |
| Age | 5.26±0.95[11] Gyr |
| α Centauri B | |
| Mass | 0.9092±0.0025[5] M☉ |
| Radius | 0.8591±0.0036[5] R☉ |
| Luminosity | 0.4981±0.0007[5] L☉ |
| Surface gravity (log g) | 4.37[7] cgs |
| Temperature | 5,207±12[8] K |
| Metallicity [Fe/H] | 0.24±0.01[8] dex |
| Rotation | 36.7±0.3 d[12] |
| Rotational velocity (v sin i) | 1.1±0.8[13] km/s |
| Age | 5.26±0.95[11] Gyr |
| Other designations | |
| Gliese 559, FK5 538, CD−60°5483, CCDM J14396-6050, GC 19728 | |
| α Cen A: Rigil Kentaurus, Rigil Kent, α1 Centauri, HR 5459, HD 128620, GCTP 3309.00, LHS 50, SAO 252838, HIP 71683 | |
| α Cen B: Toliman, α2 Centauri, HR 5460, HD 128621, LHS 51, HIP 71681 | |
| Database references | |
| SIMBAD | AB |
| A | |
| B | |
| Exoplanet Archive | data |
| ARICNS | data |
Alpha Centauri (α Centauri, α Cen, or Alpha Cen) is a star system in the southern constellation of Centaurus. It consists of three stars: Rigil Kentaurus (α Centauri A), Toliman (α Centauri B), and Proxima Centauri (α Centauri C).[14] Proxima Centauri is the closest star to the Sun at 4.2465 light-years (ly), which is 1.3020 parsecs (pc), while Alpha Centauri A and B are the nearest stars visible to the naked eye.
Rigil Kentaurus and Toliman are Sun-like stars (class G and K, respectively) that together form the binary star system α Centauri AB. To the naked eye, these two main components appear to be a single star with an apparent magnitude of −0.27. It is the brightest star in the constellation and the third-brightest in the night sky, outshone by only Sirius and Canopus. α Centauri AB are the nearest binary stars to the Sun at a distance of 4.344 ly (1.33 pc).
Rigil Kentaurus has 1.1 times the mass (M☉) and 1.5 times the luminosity of the Sun (L☉), while Toliman is smaller and cooler, at 0.9 M☉ and less than 0.5 L☉.[15] The pair orbit around a common centre with an orbital period of 79 years.[16] Their elliptical orbit is eccentric, so that the distance between A and B varies from 35.6 astronomical units (AU), or about the distance between Pluto and the Sun, to 11.2 AU, or about the distance between Saturn and the Sun.
Proxima Centauri is a small faint red dwarf (class M). Though not visible to the naked eye, Proxima Centauri is the closest star to the Sun at a distance of 4.24 ly (1.30 pc), slightly closer than α Centauri AB. The distance between Proxima Centauri and α Centauri AB is about 13,000 AU (0.21 ly),[17] equivalent to about 430 times the radius of Neptune's orbit.
Proxima Centauri has two confirmed planets — Proxima b and Proxima d. The former is an Earth-sized planet in the habitable zone (though it is unlikely to be habitable) while the latter is a sub-Earth which orbits very closely to the star.[18] A possible but disputed third planet, Proxima c, is a mini-Neptune 1.5 astronomical units away.[19] Rigil Kentaurus may have a Saturn-mass planet in the habitable zone, though it is not yet known with certainty to be planetary in nature.[20][21][22] Toliman has no known planets.[23]
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).
- ^ a b c d e f g h Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
- ^ a b c d Ducati, J. R. (2002). Catalogue of Stellar Photometry in Johnson's 11 color system. VizieR Online Data Catalog (Report). CDS/ADC Collection of Electronic Catalogues. Vol. 2237. Bibcode:2002yCat.2237....0D.
- ^ a b Torres, C.A.O.; Quast, G.R.; da Silva, L.; de la Reza, R.; Melo, C.H.F.; Sterzik, M. (2006). "Search for associations containing young stars (SACY)". Astronomy and Astrophysics. 460 (3): 695–708. arXiv:astro-ph/0609258. Bibcode:2006A&A...460..695T. doi:10.1051/0004-6361:20065602. ISSN 0004-6361. S2CID 16080025.
- ^ a b Valenti, Jeff A.; Fischer, Debra A. (2005). "Spectroscopic properties of cool stars (SPOCS) I. 1040 F, G, and K dwarfs from Keck, Lick, and AAT planet search programs". The Astrophysical Journal Supplement Series. 159 (1): 141–166. Bibcode:2005ApJS..159..141V. doi:10.1086/430500. ISSN 0067-0049.
- ^ a b c d e f g h i Akeson, Rachel; Beichman, Charles; Kervella, Pierre; Fomalont, Edward; Benedict, G. Fritz (20 April 2021). "Precision millimeter astrometry of the α Centauri AB system". The Astronomical Journal. 162 (1): 14. arXiv:2104.10086. Bibcode:2021AJ....162...14A. doi:10.3847/1538-3881/abfaff. S2CID 233307418.
- ^ a b Cite error: The named reference
Wiegertwas invoked but never defined (see the help page). - ^ a b Gilli, G.; Israelian, G.; Ecuvillon, A.; Santos, N.C.; Mayor, M. (2006). "Abundances of refractory elements in the atmospheres of stars with extrasolar planets". Astronomy and Astrophysics. 449 (2): 723–736. arXiv:astro-ph/0512219. Bibcode:2006A&A...449..723G. doi:10.1051/0004-6361:20053850. S2CID 13039037. libcode 2005astro.ph.12219G.
- ^ a b c d Soubiran, C.; Creevey, O. L.; Lagarde, N.; Brouillet, N.; Jofré, P.; Casamiquela, L.; Heiter, U.; Aguilera-Gómez, C.; Vitali, S.; Worley, C.; de Brito Silva, D. (1 February 2024). "Gaia FGK benchmark stars: Fundamental Teff and log g of the third version". Astronomy and Astrophysics. 682: A145. arXiv:2310.11302. Bibcode:2024A&A...682A.145S. doi:10.1051/0004-6361/202347136. ISSN 0004-6361. Alpha Centauri's database entry at VizieR.
- ^ Huber, Daniel; Zwintz, Konstanze; et al. (the BRITE team) (July 2020). "Solar-like oscillations: Lessons learned & first results from TESS". Stars and Their Variability Observed from Space: 457. arXiv:2007.02170. Bibcode:2020svos.conf..457H.
- ^ Bazot, M.; et al. (2007). "Asteroseismology of α Centauri A. Evidence of rotational splitting". Astronomy and Astrophysics. 470 (1): 295–302. arXiv:0706.1682. Bibcode:2007A&A...470..295B. doi:10.1051/0004-6361:20065694. S2CID 118785894.
- ^ a b Joyce, M.; Chaboyer, B. (2018). "Classically and asteroseismically constrained 1D stellar evolution models of α Centauri A and B using empirical mixing length calibrations". The Astrophysical Journal. 864 (1): 99. arXiv:1806.07567. Bibcode:2018ApJ...864...99J. doi:10.3847/1538-4357/aad464. S2CID 119482849.
- ^ Dumusque, Xavier (December 2014). "Deriving Stellar Inclination of Slow Rotators Using Stellar Activity". The Astrophysical Journal. 796 (2): 133. arXiv:1409.3593. Bibcode:2014ApJ...796..133D. doi:10.1088/0004-637X/796/2/133. S2CID 119184190.
- ^ Raassen, A.J.J.; Ness, J.-U.; Mewe, R.; van der Meer, R.L.J.; Burwitz, V.; Kaastran, J.S. (2003). "Chandra-LETGS X-ray observation of α Centauri: A nearby (G2V + K1V) binary system". Astronomy & Astrophysics. 400 (2): 671–678. Bibcode:2003A&A...400..671R. doi:10.1051/0004-6361:20021899.
- ^ Cite error: The named reference
WGSNwas invoked but never defined (see the help page). - ^ Kervella, Pierre; Thevenin, Frederic (15 March 2003). "A family portrait of the Alpha Centauri system" (Press release). European Southern Observatory. p. 5. Bibcode:2003eso..pres...39. eso0307, PR 05/03.
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SixthCatOrbVisBinwas invoked but never defined (see the help page). - ^ Kervella, P.; Thévenin, F.; Lovis, C. (January 2017). "Proxima's orbit around α Centauri". Astronomy & Astrophysics. 598: L7. arXiv:1611.03495. Bibcode:2017A&A...598L...7K. doi:10.1051/0004-6361/201629930. S2CID 50867264.
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