S Antliae
Star in the constellation Antlia
From Wikipedia, the free encyclopedia
S Antliae is a W Ursae Majoris-type eclipsing binary star in Antlia.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Antlia[2] |
| Right ascension | 09h 32m 18.38648s[3] |
| Declination | −28° 37′ 39.9685″[3] |
| Apparent magnitude (V) | 6.27 to 6.83[4] |
| Characteristics | |
| Spectral type | A9V |
| B−V color index | 0.33 |
| Variable type | Eclipsing binary W UMa type |
| Astrometry | |
| Proper motion (μ) | RA: −89.375 mas/yr[3] Dec.: +44.049 mas/yr[3] |
| Parallax (π) | 12.6116±0.0203 mas[3] |
| Distance | 258.6 ± 0.4 ly (79.3 ± 0.1 pc) |
| Absolute magnitude (MV) | 1.963[5] (2.25 + 3.42)[6] |
| Orbit[7] | |
| Period (P) | 0.59145447(30) days |
| Semi-major axis (a) | 3.82±0.02 R☉ |
| Inclination (i) | 74.02±0.14° |
| Semi-amplitude (K1) (primary) | 75±1 km/s |
| Semi-amplitude (K2) (secondary) | 234±1 km/s |
| Details[6] | |
| A | |
| Mass | 1.66±0.10 M☉ |
| Radius | 2.09±0.11 R☉ |
| Luminosity | 10.0±2.2 L☉ |
| Surface gravity (log g) | 4.02±0.03 cgs |
| Temperature | 7,100±200 K |
| B | |
| Mass | 0.55±0.05 M☉ |
| Radius | 1.31±0.06 R☉ |
| Luminosity | 3.4±0.7 L☉ |
| Temperature | 6,859±200 K |
| Age | 1.9[7] Gyr |
| Other designations | |
| CD-28°7373, HD 82610, SAO 177619, HIP 46810, HR 3798. | |
| Database references | |
| SIMBAD | data |
Characteristics
S Antiliae is classed as an A-type W Ursae Majoris variable, since the primary is hotter than the secondary and the drop in magnitude is caused by the latter passing in front of the former. S Antiliae varies in apparent magnitude from 6.27 to 6.83 over a period of 15.6 hours.[4] The system shines with a combined spectrum of A9V.[citation needed]
The system's orbital period is about 0.591 days. The stars' centres are an average of 3.82 times the Sun's radius apart. The system will evolve into an Algol variable.[6]
Calculating the properties of the component stars indicates that the primary star has a mass 1.66 times and a diameter 2.09 times that of the Sun, and the secondary has a mass 0.55 times and a diameter 1.31 times that of the Sun. The primary has a surface temperature of 7,100 K, while the secondary is a little cooler at 6,859 K.[6] The two stars have similar luminosity and spectral type as they have a common envelope and share stellar material.[citation needed] The system is thought to be around two billion years old.[7]
Based upon an annual parallax shift of 12.6116 milliarc seconds as measured by the Gaia satellite,[3] this system is 259 light-years (79.3 parsecs) from Earth. Analysing and recalibrating yields a parallax of 13.30 and hence a distance of 250 light-years (76 parsecs).[5]
History
The star's variability was first recorded in 1888 by H.M. Paul,[8] when it had the shortest known period of any variable star. It was initially thought to be an Algol-type eclipsing binary, but this was discounted by E.C. Pickering on account of it lacking a shallow minimum in its maximum and the width of its minimum period. Alfred H. Joy noted the similarity of its light curve to W Ursae Majoris in 1926, concluding the system was indeed an eclipsing binary with two stars of spectral type A8.[9]