Theta Arae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ara |
| Right ascension | 18h 06m 37.871s |
| Declination | −50° 05′ 29.31″ |
| Apparent magnitude (V) | +3.67 |
| Characteristics | |
| Spectral type | B2 Ib |
| U−B color index | −0.870 |
| B−V color index | −0.109 |
| Astrometry | |
| Radial velocity (Rv) | +3.4 km/s |
| Proper motion (μ) | RA: −8.27 mas/yr Dec.: −8.70 mas/yr |
| Parallax (π) | 4.01±0.15 mas |
| Distance | 810 ± 30 ly (249 ± 9 pc) |
| Absolute magnitude (MV) | −3.33 |
| Details | |
| Mass | 8.9±0.1 M☉ |
| Radius | 20.1 R☉ |
| Luminosity | 3,450 L☉ |
| Surface gravity (log g) | 2.70 cgs |
| Temperature | 17,231±231 K |
| Rotational velocity (v sin i) | 95 km/s |
| Age | 28.2±4.7 Myr |
| Other designations | |
| θ Ara, CD−50°11720, FK5 1471, GC 24635, HD 165024, HIP 88714, HR 6743, SAO 245242, PPM 346577 | |
| Database references | |
| SIMBAD | data |
Theta Arae is a star in the southern constellation Ara. Its name is a Bayer designation that is Latinized from θ Arae, and abbreviated Theta Ara or θ Ara. This star has an apparent visual magnitude of +3.67, which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 4.01 mas, Theta Arae is 810 light-years (250 parsecs) distant from the Earth.
This is a supergiant star with a stellar classification of B2 Ib. At an age of 28 million years, it has a high rate of spin with a projected rotational velocity of 95 km/s. This star has nearly nine times the mass of the Sun and over 20 times the Sun's radius. The outer atmosphere of this star has an effective temperature of 17,231 K; much hotter than the surface of the Sun. At this heat, the star shines with the characteristic blue-white hue of a B-type star.