Rho2 Arae
Star in the constellation Ara
From Wikipedia, the free encyclopedia
Rho2 Arae is a star in the southern constellation of Ara. Its name is a Bayer designation that is Latinized from ρ2 Arae, and abbreviated Rho2 Ara or ρ2 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.[3] Based upon an annual parallax shift of 6.28 mas, it is around 628 light-years (193 pc) distant from the Sun, give or take a 8-light-year margin of error.[2] The star is drifting closer to the Sun with a radial velocity of −44 km/s.[6]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Ara[1] |
| Right ascension | 16h 58m 17.940s[2] |
| Declination | −50° 38′ 28.27″[2] |
| Apparent magnitude (V) | 5.54[3] |
| Characteristics | |
| Spectral type | B9 IV[4] or B9 V[5] |
| B−V color index | +0.02[3] |
| Astrometry | |
| Radial velocity (Rv) | −44.0±4.3[6] km/s |
| Proper motion (μ) | RA: −9.758 mas/yr[2] Dec.: −38.302 mas/yr[2] |
| Parallax (π) | 5.2105±0.0656 mas[2] |
| Distance | 626 ± 8 ly (192 ± 2 pc) |
| Absolute magnitude (MV) | −0.47[1] |
| Details | |
| Mass | 3.42±0.10[7] M☉ |
| Radius | 5.104[8] R☉ |
| Luminosity | 238+34 −30[7] L☉ |
| Temperature | 10,520±49[8] K |
| Rotational velocity (v sin i) | 302[7] km/s |
| Other designations | |
| ρ2 Ara, CD50°10924, FK5 1444, GC 22841, HD 152824, HIP 83057, HR 6289, SAO 244313, PPM 345560[9] | |
| Database references | |
| SIMBAD | data |
The spectrum of this star matches a stellar classification of B9 IV[4] or B9 V.[5] The IV luminosity class suggests 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.[7]
Rho2 Arae has more than three times the mass of the Sun and 5.1 times the Sun's radius.[8] It is radiating 238 times the Sun's luminosity[7] from the star's photosphere at an effective temperature of 10,520 K,[8] giving it the blue-white hue of a B-type star.[10] The star is spinning rapidly with a projected rotational velocity of 302 km/s.[7]