Gamma Trianguli Australis
Template:Location mark Location of γ Trianguli Australis (circled) | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Triangulum Australe |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | +2.87[2] |
| Characteristics | |
| Evolutionary stage | Subgiant[3] |
| Spectral type | A1III[3] |
| U−B Template:Engvar | −0.02[4] |
| B−V Template:Engvar | +0.00[4] |
| Astrometry | |
| Radial velocity (Rv) | −3.0[2] km/s |
| Proper motion (μ) | RA: −65.816 mas/yr[1] Dec.: −31.187 mas/yr[1] |
| Parallax (π) | 17.1809±0.3327 mas[1] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)[1] |
| Absolute magnitude (MV) | −0.89[5] |
| Details[3] | |
| Mass | 3.04 Template:Solar mass |
| Radius | 6.5 or 7 Template:Solar radius |
| Luminosity | 249[6] Template:Solar luminosity |
| Surface gravity (log g) | 3.39[7] cgs |
| Temperature | 8,225 K |
| Rotational velocity (v sin i) | 199[8] km/s |
| Age | 350 Myr |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist[9] | |
| Database references | |
| SIMBAD | data |
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Gamma Trianguli Australis, Latinized from γ Trianguli Australis, is a 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.[2] Based upon parallax measurements, Gamma Trianguli Australis is located at a distance of about Script error: No such module "convert". from Earth.[1]
Characteristics
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.[3] An unusual abundance of the element europium demonstrates it to be a peculiar, or Ap star.[10] However, its classification as a chemically peculiar star is doubtful.[3] Most stars of this type are slow rotators,[11] but Gamma Trianguli Australis displays a very high rate of rotation with a projected rotational velocity of 199 km s−1.[8]
At a mass of 3.04Script error: No such module "String".solar 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 Template:Solar radius (estimated using stellar isochrones) or Template:Solar radius (measured).[3] The star is emitting a luminosity equivalent to 250Script error: No such module "String".solar luminosities.[6] Its surface has an effective temperature of Script error: No such module "val"..[3] This is around Script error: No such module "val". hotter than the Sun[12] and gives it a white hue, typical of A-type stars.[13]
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.[14]
Reported companion star
The Gaia Data Release 3 (Gaia DR3) reported Gamma Trianguli Australis as an astrometric binary with a period of Script error: No such module "convert".. The companion star would be a red dwarf with a mass of Template:Solar mass and a semimajor axis of Script error: No such module "val".. However, a further study using the Very Large Telescope did not find any evidence of a companion, placing constraints on the properties of the putative companion.[3]
Modern legacy
γ TrA appears on the flag of Brazil, symbolising the state of Paraná.[15]
References
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