Zeta Trianguli Australis

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Zeta Trianguli Australis
Observation data
Epoch J2000      Equinox J2000
Constellation Triangulum Australe
Right ascension 16h 28m 28.1s
Declination −70° 05′ 04″
Apparent magnitude (V) 4.90
Spectral type F9 V (F6V + G1V)
U−B color index 0.03
B−V color index 0.55[1]
Radial velocity (Rv) +7.6 km/s
Proper motion (μ) RA: 199.88 mas/yr
Dec.: 110.77 mas/yr
Parallax (π) 82.61 ± 0.57 mas
Distance 39.5 ± 0.3 ly
(12.11 ± 0.08 pc)
Absolute magnitude (MV) 4.49
Metallicity [Fe/H] –0.18[1] dex
Rotation 13 days[1]
Age 600–900[2] Myr
Other designations
Gl 624, HR 6098, CD -69°2558, HD 147584, LTT 6558, GCTP 3719.00, SAO 253554, FK5 610, GC 22089, HIP 80686.

Zeta Trianguli Australis (ζ TrA) is a spectroscopic binary in the constellation Triangulum Australe. It is approximately 39.5 light years from Earth.

The system is composed of two main sequence stars, one a yellow-white F-type dwarf and the other a yellow G-type dwarf. The binary's composite spectral class is F9V and its combined apparent magnitude is +4.90. The pair orbit each other once every 13 days, and the orbital eccentricity is 0.014.[3]

Somewhat surprisingly for a star located at 70° S, it is a candidate swarm member of the Ursa Major moving group.[4] However, there is some evidence to the contrary.[1]


  1. ^ a b c d Maldonado, J. et al. (October 2010), "A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups", Astronomy and Astrophysics 521: A12, arXiv:1007.1132, Bibcode:2010A&A...521A..12M, doi:10.1051/0004-6361/201014948 
  2. ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008), "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics", The Astrophysical Journal 687 (2): 1264–1293, arXiv:0807.1686, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785 
  3. ^ Skuljan, Jovan (2004), "Accurate orbital parameters for the bright southern spectroscopic binary ζ Trianguli Australis – an interesting case of a near-circular orbit", Monthly Notices of the Royal Astronomical Society 352: 975, Bibcode:2004MNRAS.352..975S, doi:10.1111/j.1365-2966.2004.07988.x 
  4. ^ Croswell, Ken (2005). "Descendants of the Dipper". Astronomy 33 (3): 40–45. ISSN 0091-6358.