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