Beta Arae
 Location of β Arae (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Ara |
| Right ascension | 17h 25m 17.98835s |
| Declination | −55° 31′ 47.5868″ |
| Apparent magnitude (V) | 2.84 |
| Characteristics | |
| Spectral type | K3 Ib-II |
| U−B color index | +1.56 |
| B−V color index | +1.46 |
| Astrometry | |
| Radial velocity (Rv) | -0.30 ± 0.20 km/s |
| Proper motion (μ) |
RA: −8.51 mas/yr Dec.: −25.24 mas/yr |
| Parallax (π) | 5.05 ± 0.64mas |
| Distance | approx. 650 ly (approx. 200 pc) |
| Absolute magnitude (MV) | −3.494 |
| Details | |
| Mass | 8.21 M☉ |
| Luminosity | 5,636 L☉ |
| Surface gravity (log g) | 1.20 cgs |
| Temperature | 4,197 K |
| Metallicity [Fe/H] | −0.05 dex |
| Rotational velocity (v sin i) | 5.4 ± 1.0 km/s |
| Age | 50.1 ± 4.4 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Beta Arae (β Ara, β Arae) is the brightest star in the constellation Ara, with an apparent visual magnitude of 2.8.Parallax measurements place it at a distance of roughly 650 light-years (200 parsecs) from Earth.
The spectrum of this star matches a stellar classification of K3 Ib-IIa, with the luminosity class notation 'Ib-IIa' indicating that the star lies part way between a higher luminosity bright giant (IIa) and a lower luminosity supergiant (Ib). This represents two of the evolutionary stages that a massive star passes through after it has exhausted the hydrogen at its core. Beta Arae is radiating energy from its outer envelope at an effective temperature of 4,200 K, which causes it to take on the orange hue of a K-type star. This enlarged star appears to be rotating slowly with a projected rotational velocity of about 5 km/s. The abundance of elements other than hydrogen and helium, what astronomer term the star's metallicity, is more than three times the abundance in the Sun.
Rarely, this star is called by the name Vasat-ül-cemre in Turkish spelling, derived from Arabic word ﻭﺳﻂ (wasath) and ﺟﻤﻩﺮ (khamra), meaning "middle of fire". In Chinese, 杵 (Chǔ), meaning Pestle, refers to an asterism consisting of β Arae, σ Arae and α Arae. Consequently, β Arae itself is known as 杵三 (Chǔ sān, English: the Third Star of Pestle.)
...
Wikipedia