Gamma Trianguli Australis, Latinized from γ Trianguli Australis, is a single, white-hued star in the southern constellation of Triangulum Australe. Along with Alpha and Beta Trianguli Australis it forms a prominent triangular asterism that gives the constellation its name (Latin for southern triangle). It is the third-brightest member of this constellation with an apparent visual magnitude of +2.87. Based upon parallax measurements, Gamma Trianguli Australis is located at a distance of about 190abbr=offNaNabbr=off from Earth.
The spectrum of this star matches a stellar classification of A1 III, which identifies it as a giant star. It could be also a subgiant. An unusual abundance of the element europium demonstrates it to be a peculiar, or Ap star. However, its classification as a chemically peculiar star is doubtful. Most stars of this type are slow rotators, but Gamma Trianguli Australis displays a very high rate of rotation with a projected rotational velocity of 199 km s−1.
At a mass of 3.04solar masses, Gamma Trianguli Australis was a late B-type star (B8V/B9V) in the main sequence. Being 350 million years old, it has recently begun its expansion towards a red giant. Its radius is either (estimated using stellar isochrones) or (measured). The star is emitting a luminosity equivalent to 250solar luminosities. Its surface has an effective temperature of . This is around hotter than the Sun[1] and gives it a white hue, typical of A-type stars.
This star shows an excess emission of infrared radiation, suggesting that there is a circumstellar disk of dust orbiting this star. The mean temperature of the emission is 50 K, corresponding to a separation from the star of 481 astronomical units.
The Gaia Data Release 3 (Gaia DR3) reported Gamma Trianguli Australis as an astrometric binary with a period of 488day. The companion star would be a red dwarf with a mass of and a semimajor axis of . However, a further study using the Very Large Telescope did not found any evidence of a companion.
γ TrA appears on the flag of Brazil, symbolising the state of Paraná.[2]