Kappa Tucanae

Kappa Tucanae, Latinised from, κ Tucanae, is a quadruple[5] star system in the southern constellation Tucana. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of either +4.25[2] or +4.86,[3] depending on the source. The system is located approximately 68 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +8 km/s.[2]

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[2] or +4.86[3]
(5.00 + 7.74 + 7.84 + 8.44)[4]
Characteristics
Spectral type F6 IV + G5 V + K2V + ?[5]
B−V color index 0.48[6]
Astrometry
Radial velocity (Rv)+7.7±1.7[2] km/s
Proper motion (μ) RA: +412.11[1] mas/yr
Dec.: +127.74[1] mas/yr
Parallax (π)47.72 ± 0.41 mas[1]
Distance68.3 ± 0.6 ly
(21.0 ± 0.2 pc)
Absolute magnitude (MV)3.50[6]
Orbit[7]
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)
(secondary)		284.9°
Details
κ Tuc A
Mass1.37[8] M☉
Temperature6,366[6] K
Rotational velocity (v sin i)61.1±3.1[6] km/s
κ Tuc B
Mass0.85[8] M☉
Other designations
κ Tuc, HD 7788, HIP 5896, HR 377, SAO 248346[9]
Database references
SIMBADdata

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 +5.0. 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.[7]

The other binary pair, the magnitude +7.8 C, and the magnitude +8.4 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.

References
  1. 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.
  2. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  3. Hoffleit, D.; Warren, Jr., W. H. (1991), The Bright Star Catalogue (5th Revised ed.), retrieved 2019-09-16.
  4. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466, Bibcode:2001AJ....122.3466M, doi:10.1086/323920.
  5. 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.
  6. Ammler-von Eiff, Matthias; Reiners, Ansgar (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:1204.2459, Bibcode:2012A&A...542A.116A, doi:10.1051/0004-6361/201118724, S2CID 53666672.
  7. "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 2017-08-01. Retrieved 2017-07-01.
  8. Tokovinin, A.; Kiyaeva, O. (2015). "Eccentricity distribution of wide binaries". Monthly Notices of the Royal Astronomical Society. 456 (2): 2070. arXiv:1512.00278. Bibcode:2016MNRAS.456.2070T. doi:10.1093/mnras/stv2825.
  9. "kap Tuc -- Double or multiple star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-04-21.
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