Wikipedia

2 Centauri

This article is about g Centauri; it is not to be confused with G Centauri.
2 Centauri
Location of 2 Centauri (circled in red)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Centaurus
Right ascension 13h 49m 26.72175s[1]
Declination −34° 27′ 02.7929″[1]
Apparent magnitude (V) 4.16–4.26[2]
Characteristics
Evolutionary stage AGB[3]
Spectral type M5 III[4]
U−B color index +1.44[5]
B−V color index +1.49[5]
Variable type SRb[2]
Astrometry
Radial velocity (Rv)+40.7±0.7[6] km/s
Proper motion (μ) RA: −41.68±0.23[1] mas/yr
Dec.: −59.77±0.18[1] mas/yr
Parallax (π)17.82±0.21 mas[1]
Distance183 ± 2 ly
(56.1 ± 0.7 pc)
Absolute magnitude (MV)+0.51[7]
Details
Mass1.0[8] M☉
Radius82.4[9] R☉
Luminosity767[8] L☉
Surface gravity (log g)0.65[8] cgs
Temperature3,438[8] K
Other designations
g Centauri, 2 Cen, V806 Cen, CD−33°9358, GC 18666, HD 120323, HIP 67457, HR 5192, SAO 204875[10]
Database references
SIMBADdata

2 Centauri is a single[11] star in the southern constellation of Centaurus, located approximately 183 light-years from Earth.[1] It has the Bayer designation g Centauri;[10] 2 Centauri is the Flamsteed designation. This object is visible to the naked eye as faint, red-hued star with an apparent visual magnitude of about 4.2. It is moving away from the Earth with a heliocentric radial velocity of +41 km/s.[6] The star is a member of the HR 1614 supercluster.[12]

A light curve for V806 Centauri. The main plot shows the long term variability from Hipparcos data,[13] and the inset plot shows the variability over the 26.5 day period, using data from Tabur et al. (2009).[14] The green curve shows the best-fit sine wave, which has an amplitude of 18 millimagnitudes.

This is an evolved red giant star with a stellar classification of M5 III.[4] In 1951, Alan William James Cousins announced that the star, then called g Centauri, is a variable star.[15] It was given its variable star designation, V806 Centauri, in 1978.[16] It is classified as a semiregular variable star and its brightness varies from magnitude +4.16 to +4.26[2] with a period of 12.57 days.[17] The star has around 82 times the Sun's radius and is radiating 767 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,438 K.

References

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  1. ^ a b c d e f 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. Vizier catalog entry
  2. ^ a b c Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. ^ Eggen, Olin J. (1992). "Asymptotic Giant Branch Stars Near the Sun". The Astronomical Journal. 104: 275. Bibcode:1992AJ....104..275E. doi:10.1086/116239.
  4. ^ a b Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 5. Bibcode:1999MSS...C05....0H.
  5. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. ^ a b Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  7. ^ Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics, 430: 303–311, arXiv:astro-ph/0409683, Bibcode:2005A&A...430..303C, doi:10.1051/0004-6361:20041440, S2CID 12136256.
  8. ^ a b c d Ayres, Thomas (2023). "In the Trenches of the Solar-Stellar Connection. VII. Wilson-Bappu 2022". The Astrophysical Journal Supplement Series. 266 (1): 6. Bibcode:2023ApJS..266....6A. doi:10.3847/1538-4365/acb535.
  9. ^ Wood, Brian E.; Harper, Graham M.; Müller, Hans-Reinhard (May 2024). "Resolving Red Giant Winds with the Hubble Space Telescope*". The Astrophysical Journal. 967 (2): 120. arXiv:2404.15086. doi:10.3847/1538-4357/ad401f. ISSN 0004-637X.
  10. ^ a b "2 Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-04-06.
  11. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  12. ^ Eggen, Olin J. (June 1998). "The HR 1614 Group and HIPPARCOS Astrometry". The Astronomical Journal. 115 (6): 2453–2458. Bibcode:1998AJ....115.2453E. doi:10.1086/300380.
  13. ^ "Hipparcos Tools Interactive Data Access". Hipparcos. ESA. Retrieved 8 December 2021.
  14. ^ Tabur, V.; Bedding, T. R.; Kiss, L. L.; Moon, T. T.; Szeidl, B.; Kjeldsen, H. (2009). "Long-term photometry and periods for 261 nearby pulsating M giants". Monthly Notices of the Royal Astronomical Society. 400 (4): 1945–1961. arXiv:0908.3228. Bibcode:2009MNRAS.400.1945T. doi:10.1111/j.1365-2966.2009.15588.x.
  15. ^ Cousins, A. W. J. (October 1951). "Photographic magnitudes of the brightest stars". The Observatory. 71: 201–202. Bibcode:1951Obs....71..201C. Retrieved 16 January 2025.
  16. ^ Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (April 1978). "63rd Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 1414: 1–10. Bibcode:1978IBVS.1414....1K. Retrieved 16 January 2025.
  17. ^ Ruban, E. V.; Arkharov, A. A.; Hagen-Thorn, E. I.; Novikov, V. V. (September 2009). "Physical parameters of the semiregular variable red giant 2 Cen". Astrophysics. 52 (3): 383–394. Bibcode:2009Ap.....52..383R. doi:10.1007/s10511-009-9075-3. S2CID 121256121.