S Trianguli Australis
Variable star in the constellation Triangulum Australe
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S Trianguli Australis is a yellow-white hued variable star in the constellation Triangulum Australe. It is a dim star near the lower limit of visibility with the naked eye, having a typical apparent visual magnitude of about six. Based upon an annual parallax shift of 1.08 mas,[2] it is located 3,030 light years from the Earth.
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Triangulum Australe |
| Right ascension | 16h 01m 10.71590s[2] |
| Declination | −63° 46′ 35.5324″[2] |
| Apparent magnitude (V) | 5.95 – 6.81[3] |
| Characteristics | |
| Spectral type | F8 II[4] |
| B−V color index | 0.567±0.020[5] |
| Variable type | δ Cep[6] |
| Astrometry | |
| Radial velocity (Rv) | 2.2±1.3[7] km/s |
| Proper motion (μ) | RA: −2.244[2] mas/yr Dec.: −2.804[2] mas/yr |
| Parallax (π) | 1.0753±0.0301 mas[2] |
| Distance | 3,030 ± 80 ly (930 ± 30 pc) |
| Absolute magnitude (MV) | −3.53[8] |
| Details | |
| Mass | 2.8[9] M☉ |
| Radius | 39.2[9] R☉ |
| Surface gravity (log g) | 2.1±0.1[10] cgs |
| Temperature | 5,976±67[10] K |
| Metallicity [Fe/H] | 0.12±0.05[10] dex |
| Other designations | |
| S TrA, CD−63° 1146, HD 142941, HIP 78476, HR 5939, SAO 253377[11] | |
| Database references | |
| SIMBAD | data |
Benjamin Apthorp Gould discovered that this star's brightness varies, and published that discovery in his 1879 work Uranometria Argentina.[12][3] A Classical Cepheid variable, its apparent magnitude ranges from 5.95 to 6.81 over 6.32344 days.[3] It is a bright giant with a nominal stellar classification of F8 II,[4] that pulsates between spectral types F6II-G2.[3] The star has 2.8 times the mass of the Sun and 39.2 times the Sun's radius.[9] It is losing mass at the estimated rate of 2.8×10−10 M☉·yr−1.[8]