Gamma Tucanae

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γ Tucanae
Tucana constellation map.svg
Red circle.svg
Location of γ Tucanae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Tucana
Right ascension 23h 17m 25.77222s[1]
Declination −58° 14′ 08.6287″[1]
Apparent magnitude (V) +3.99[2]
Spectral type F1 III[2][3] or F3 IV/V[4] or F4 V[5]
U−B color index -0.02[6]
B−V color index +0.39[6]
Radial velocity (Rv) +18.4±0.7[7] km/s
Proper motion (μ) RA: -35.83[1] mas/yr
Dec.: +81.16[1] mas/yr
Parallax (π) 43.37 ± 0.63[1] mas
Distance 75 ± 1 ly
(23.1 ± 0.3 pc)
Absolute magnitude (MV) 2.18[8]
Mass 1.55[2] M
Radius 2.2[9] R
Luminosity 11.33[8] L
Surface gravity (log g) 3.92[10] cgs
Temperature 6,679[10] K
Metallicity [Fe/H] −0.22[8] dex
Rotational velocity (v sin i) 94[11] km/s
Age 1.414[10] Gyr
Other designations
γ Tuc, CPD−58° 8062, FK5 877, GC 32413, GJ 9818, HD 219571, HIP 114996, HR 8848, SAO 247814, GSC 08837-01297[12]
Database references

Gamma Tucanae, Latinized from γ Tucanae, is a star in the constellation Tucana, marking the toucan's beak.[13] It is faintly visible to the naked eye with an apparent visual magnitude of +3.99.[2] Based upon an annual parallax shift of 43.37 mas as seen from Earth,[1] this star is located about 75 light years from the Sun. It is moving away from the Sun with a radial velocity of +18 km/s.[7]

There is disagreement in the literature as to the stellar classification of this star. Malaroda (1975) has it catalogued as F1 III, which would suggest it is an evolved F-type giant star.[3] Houk (1979) listed it as F3 IV/V, which appears to indicate a less evolved F-type star transitioning between the main sequence and subgiant star.[4] Gray et al. (2006) has it classed as F4 V, which would match an ordinary F-type main-sequence star.[5]

This star is a suspected astrometric binary.[14] The visible component has 1.55 times the mass of the Sun[2] and 2.2[9] times the Sun's radius. At the age of around 1.4[10] billion years, it retains a relatively high rate of spin with a projected rotational velocity of 94 km/s.[11] It is radiating 11[8] times the Sun's luminosity from its photosphere at an effective temperature of 6,679 K.[10]

Gamma Tucanae may (95% chance) have a distant co-moving companion – a magnitude 6.64 G-type main-sequence star of class G0 V designated HD 223913. This object has the same mass as the Sun and is separated from Gamma Tucanae by about 11 ly (3.5 pc).[15]


  1. ^ a b c d e f Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b c d e Shaya, Ed J.; Olling, Rob P. (January 2011), "Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue", The Astrophysical Journal Supplement, 192 (1): 2, arXiv:1007.0425Freely accessible, Bibcode:2011ApJS..192....2S, doi:10.1088/0067-0049/192/1/2 
  3. ^ a b Malaroda, S. (August 1975), "Study of the F-type stars. I. MK spectral types", Astronomical Journal, 80: 637–641, Bibcode:1975AJ.....80..637M, doi:10.1086/111786. 
  4. ^ a b Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Department of Astronomy, University of Michigan, 
  5. ^ a b Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770Freely accessible, Bibcode:2006AJ....132..161G, doi:10.1086/504637. 
  6. ^ a b Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D. 
  7. ^ 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. arXiv:1606.08053Freely accessible. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  8. ^ a b c d Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971Freely accessible. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015.  Vizier catalog entry
  9. ^ a b Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555. arXiv:astro-ph/9911002Freely accessible. Bibcode:1999A&A...352..555A.  Vizier catalog entry
  10. ^ a b c d e David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154Freely accessible. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.  Vizier catalog entry
  11. ^ a b Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H. 
  12. ^ "Gamma Tucanae". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 20 October 2013. 
  13. ^ Knobel, E. B. (1917). "On Frederick de Houtman's Catalogue of Southern Stars, and the Origin of the Southern Constellations". Monthly Notices of the Royal Astronomical Society. 77 (5): 414–32 [430]. Bibcode:1917MNRAS..77..414K. doi:10.1093/mnras/77.5.414. 
  14. ^ 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:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  15. ^ Shaya, Ed J.; Olling, Rob P. (January 2011), "Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue", The Astrophysical Journal Supplement, 192 (1): 2, arXiv:1007.0425Freely accessible, Bibcode:2011ApJS..192....2S, doi:10.1088/0067-0049/192/1/2