Zeta Trianguli Australis
{{Short description|Binary star system in the constellation Triangulum Australe}}
{{Starbox begin
| name=Zeta Trianguli Australis
}}
{{Starbox observe
| epoch=J2000
| constell=Triangulum Australe
}}
{{Starbox character
| variable=
}}
{{Starbox astrometry
| prop_mo_ra=200.742
| prop_mo_dec=109.341
| parallax=82.8699
| p_error=0.1627
}}
{{Starbox orbit
| period_unitless = 12.97662{{±|0.00017}} d
| eccentricity = 0.01442{{±|0.00021}}
| periastron = JD 2452752.31955
| periarg = 252.98°{{±|0.80}}
| k1 = 7.4988{{±|0.0016}}
}}
{{Starbox detail
| component1=ζ TrA A
| luminosity=
| temperature={{Val|6032|70|fmt=commas}}
| metal_fe= {{val|-0.09|0.06}}
| component2=ζ TrA B
}}
{{Starbox catalog
| names={{odlist | CD=-69°2558 | FK5=610 | GCTP=3719.00 | GJ=624 | HD=147584 | HIP=80686 | HR=6098 | LTT=6558 | SAO=253554 }}
}}
{{Starbox reference
| Simbad = zet+TrA
| ARICNS = 01299
}}
{{Starbox end}}
Zeta Trianguli Australis (ζ TrA) is a spectroscopic binary star system in the southern constellation Triangulum Australe. The pair have a combined apparent visual magnitude of 4.90, which is bright enough to be visible to the naked eye. Based on parallax measurements, the system is located at a distance of approximately 39.4 light years from Earth. After closing to within {{cvt|9.59|pc|ly|order=flip}} some 436,600 years ago, it is now drifting further away with a radial velocity of +8.3 km/s.
The pair orbit each other once every 13 days, and the orbital eccentricity is a low 0.014, making their orbit nearly circular. The primary component has a stellar classification of F9V, matching an F-type main-sequence star. It has a mass equal to 1.12 times the mass of the Sun, a radius 1.06 times the radius of the Sun, and irradiated at an effective temperature of {{val|fmt=commas|6032|ul=K}}, slightly hotter than the Sun as well. The companion is a small red dwarf star with a class in the range of M1–7V and 40% of the Sun's mass. The age of the system is estimated at 600–900 million years.
Somewhat surprisingly for a star located at a declination of 70° S, it is a candidate swarm member of the Ursa Major moving group. However, there is some evidence to the contrary.
References
{{reflist|refs=
{{cite simbad | title=zet TrA | access-date=2024-10-21 }}
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}}
{{Stars of Triangulum Australe}}
{{DEFAULTSORT:Zeta Trianguli Australis}}
Category:F-type main-sequence stars
Category:G-type main-sequence stars
Category:Spectroscopic binaries