Kappa Tucanae

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Kappa Tucanae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Tucana
Right ascension 01h 15m 46.16226s[1]
Declination −68° 52′ 33.3356″[1]
Apparent magnitude (V) +4.25 (5.00 / 7.74)[2]
Spectral type F6 IV + G5 V + K2V + ?[3]
B−V color index 0.48[4]
Proper motion (μ) RA: +412.11[1] mas/yr
Dec.: +127.74[1] mas/yr
Parallax (π) 47.72 ± 0.41[1] mas
Distance 68.3 ± 0.6 ly
(21.0 ± 0.2 pc)
Absolute magnitude (MV) 3.50[4]
Period (P) 857.0 yr
Semi-major axis (a) 5.960″
Eccentricity (e) 0.384
Inclination (i) 127.1°
Longitude of the node (Ω) 10.3°
Periastron epoch (T) 1763.50
Argument of periastron (ω)
κ Tuc A
Mass 1.37[5] M
Temperature 6,366[4] K
Rotational velocity (v sin i) 61.1±3.1[4] km/s
κ Tuc B
Mass 0.85[5] M
Other designations
κ Tuc, CD−69° 45, HD 7788, HIP 5896, HR 377, SAO 248346[6]
Database references

Kappa Tucanae (κ Tuc, κ Tucanae) is a quadruple[3] star system in the constellation Tucana. It is approximately 66.6 light years from Earth and the combined apparent magnitude of the system is +4.25.

The system consists of two binary pairs separated by 5.3 arcminutes. The brightest star, Kappa Tucanae A, is a yellow-white F-type subgiant with an apparent magnitude of +5.1. Its binary companion, Kappa Tucanae B, has a magnitude of 7.74 and is located about 6″ away from the primary. It completes an orbit around the primary every 857 years.[2]

The other binary pair, the magnitude +7.8 C, and the magnitude +8.2 D, are closer to one another, at 1.12 arcseconds, or at least 23 astronomical units. They orbit each other once every 86.2 years.


  1. ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 2017-07-01. 
  3. ^ a b 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. 
  4. ^ a b c d Ammler-von Eiff, M.; Reiners, A. (June 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics, 542: A116, arXiv:1204.2459Freely accessible, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724. 
  5. ^ a b Tokovinin, A.; Kiyaeva, O. (2015). "Eccentricity distribution of wide binaries". Monthly Notices of the Royal Astronomical Society. 456 (2): 2070. arXiv:1512.00278Freely accessible. Bibcode:2016MNRAS.456.2070T. doi:10.1093/mnras/stv2825. 
  6. ^ "kap Tuc -- Double or multiple star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-04-21.