Zeta Trianguli Australis
Encyclopedia
Zeta Trianguli Australis (ζ TrA) is a spectroscopic binary in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

 Triangulum Australe
Triangulum Australe
Triangulum Australe is a small constellation in the southern sky, created in the sixteenth century. Its name is Latin for 'the southern triangle', which distinguishes it from Triangulum in the northern sky...

. It is approximately 39.5 light years
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....

 from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

.

The system is composed of two main sequence
Main sequence
The main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell...

 stars, one a yellow-white F-type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...

 dwarf and the other a yellow G-type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...

 dwarf. The binary's
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...

 composite spectral class
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...

 is F9V and its combined apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...

 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
Ursa Major Moving Group
The Ursa Major Moving Group, also known as Collinder 285 or Ursa Major association, is a nearby stellar moving group, a set of stars with common velocities in space and thought to have a common origin. Its core is located roughly 80 light years away...

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