Zeta Trianguli Australis

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**Zeta Trianguli Australis**
Observation data Epoch J2000
Constellation (pronunciation)	Triangulum Australe
Right ascension	16^h 28^m 28.1^s
Declination	-70° 05′ 04″
Apparent magnitude (V)	4.90
Characteristics
Spectral type	F9 V (F6V + G1V)
U-B color index	0.03
B-V color index	0.54
Variable type	?
Astrometry
Radial velocity (R_v)	+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 (M_V)	4.49
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.

Somewhat surprisingly for a star located at 70° S, it is a swarm member of the Ursa Major moving group.

[edit] References

Jovan Skuljan, 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, Volume 352, p. 975.