Rho2 Arae

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]

For other stars with this Bayer designation, see ρ Arae.

Rho² Arae

The location of ρ2 Arae (circled)
Observation data Epoch J2000      Equinox J2000
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]