R Trianguli Australis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Triangulum Australe |
| Right ascension | 15h 19m 45.71231s |
| Declination | −66° 29′ 45.7417″ |
| Apparent magnitude (V) | 6.73 (6.33 - 6.90) |
| Characteristics | |
| Spectral type | F7 Ib/II |
| Variable type | δ Cep |
| Astrometry | |
| Radial velocity (Rv) | −13.2±1.6 km/s |
| Proper motion (μ) | RA: −5.113 mas/yr Dec.: −8.317 mas/yr |
| Parallax (π) | 1.4754±0.0371 mas |
| Distance | 2,210 ± 60 ly (680 ± 20 pc) |
| Absolute magnitude (MV) | 2.69 |
| Details | |
| Mass | 5.42 or 5.66 M☉ |
| Radius | 24.7±1.9 or 35.8±0.8 R☉ |
| Surface gravity (log g) | 2.10 cgs |
| Temperature | 5,852±21 K |
| Metallicity [Fe/H] | +0.06±0.08 dex |
| Rotational velocity (v sin i) | 16 km/s |
| Other designations | |
| R TrA, CD−66° 1728, HD 135592, HIP 75018, SAO 253107 | |
| Database references | |
| SIMBAD | data |
R Trianguli Australis is a yellow-white hued variable star in the southern constellation Triangulum Australe. It is near the limit of visibility to the naked eye, having a typical apparent visual magnitude of 6.73. Based upon an annual parallax shift of 1.48 mas, it is located 2,210 light years away. R TrA is moving closer with a heliocentric radial velocity of −13 km/s.
This is a Classical Cepheid variable with an apparent magnitude that ranges from 6.33 to 6.90 over 3.38926 days. It is a bright giant/supergiant with a nominal stellar classification of F7 Ib/II, but pulsates between spectral types F5Ib/II-G5. Depending on the method employed, the estimated mass is 5.42 or 5.66 times the mass of the Sun and it has 24.7 or 35.8 times the Sun's radius. R TrA has an infrared excess that is being emitted by circumstellar silicate dust heated to 150–200 K. It is losing mass at the rate of 4×10−9 M☉·y−1.