Rho2 Arae
 The location of ρ2 Arae (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Ara |
| Right ascension | 16h 58m 17.94161s[1] |
| Declination | –50° 38′ 28.2691″[1] |
| Apparent magnitude (V) | 5.54[2] |
| Characteristics | |
| Spectral type | B9 IV[3] or B9 V[4] |
| B−V color index | +0.02[2] |
| Astrometry | |
| Radial velocity (Rv) | –44.0[5] km/s |
| Proper motion (μ) | RA: –8.05[1] mas/yr Dec.: –38.68[1] mas/yr |
| Parallax (π) | 6.28 ± 0.38[1] mas |
| Distance | 520 ± 30 ly (159 ± 10 pc) |
| Details | |
| Mass | 3.42 ± 0.10[6] M☉ |
| Luminosity | 238[6] L☉ |
| Temperature | 10,520[6] K |
| Rotational velocity (v sin i) | 302[6] km/s |
| Other designations | |
Rho2 Arae is the Bayer designation for a star in the southern constellation of Ara. It received this designation when the star was catalogued by Bode in his Uranographia. This is a rather dim naked eye star with an apparent visual magnitude of 5.54.[2] Based upon an annual parallax shift of just 6.28 mas, it is around 520 light-years (160 parsecs) distant from the Sun, give or take a 30 light-year margin of error.[1]
The spectrum of this star matches a stellar classification of B9 IV[3] or B9 V.[4] The IV luminosity class would indicate the star is in the subgiant stage, while a V class means it is a main sequence star like the Sun. In the latter case, it is close to entering the subgiant stage at an estimated 93% of the way through its lifespan on the main sequence.[6]
Rho2 Arae has more than three times the mass of the Sun and shines with 238 times the Sun's luminosity.[6] This energy is being radiated into space from the outer atmosphere at an effective temperature of 10,520 K,[6] giving it the blue-white hue of a B-type star.[8] It is spinning rapidly with a projected rotational velocity of 302 km/s.[6]
References
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