S Trianguli Australis

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 6.41.^[3] Based upon an annual parallax shift of 1.08 mas,^[2] it is located 3,030 light years from the Earth.

S Trianguli Australis

A light curve for S Trianguli Australis, plotted from Hipparcos data[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Triangulum Australe
Right ascension	16h 01m 10.71590s[2]
Declination	−63° 46′ 35.5324″[2]
Apparent magnitude (V)	6.41[3] (5.95 – 6.81)[4]
Characteristics
Spectral type	F8 II[5]
B−V color index	0.567±0.020[6]
Variable type	δ Cep[7]
Astrometry
Radial velocity (Rv)	2.2±1.3[8] 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[9]
Details
Mass	2.8[10] M☉
Radius	39.2[10] R☉
Surface gravity (log g)	2.1±0.1[3] cgs
Temperature	5,976±67[3] K
Metallicity [Fe/H]	0.12±0.05[3] 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][4] A Classical Cepheid variable, its apparent magnitude ranges from 5.95 to 6.81 over 6.32344 days.^[4] It is a bright giant with a nominal stellar classification of F8 II,^[5] that pulsates between spectral types F6II-G2.^[4] The star has 2.8 times the mass of the Sun and 39.2 times the Sun's radius.^[10] It is losing mass at the estimated rate of 2.8×10⁻¹⁰ M_☉·yr⁻¹.^[9]