Rho Aquarii, Latinized from ρ Aquarii, is the Bayer designation for a binary star[8] system in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent visual magnitude of +5.34.[2] Based upon parallax measurements, this star is at a distance of roughly 870 light-years (270 parsecs) from Earth.[1] It is drifting closer with a radial velocity of –9 km/s.[4] The proximity of this star to the ecliptic means it is subject to lunar occultations.[10]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Aquarius |
Right ascension | 22h 20m 11.91830s[1] |
Declination | –07° 49′ 15.9742″[1] |
Apparent magnitude (V) | +5.34[2] |
Characteristics | |
Spectral type | B8 IIIp Mn:Hg:[3] |
U−B color index | –0.358[2] |
B−V color index | –0.057[2] |
Astrometry | |
Radial velocity (Rv) | –9[4] km/s |
Proper motion (μ) | RA: +13.201[1] mas/yr Dec.: +0.030[1] mas/yr |
Parallax (π) | 3.7483 ± 0.1608 mas[1] |
Distance | 870 ± 40 ly (270 ± 10 pc) |
Absolute magnitude (MV) | −1.78[5] |
Orbit[6] | |
Period (P) | 220.41±0.10 d |
Periastron epoch (T) | 2,418,548.7±7.4 JD |
Semi-amplitude (K1) (primary) | 18.66±2.75 km/s |
Details | |
A | |
Mass | 5.00±0.22[7] M☉ |
Luminosity | 1,035[7] L☉ |
Temperature | 12,593[8] K |
Rotational velocity (v sin i) | 65[3] km/s |
Other designations | |
Database references | |
SIMBAD | data |
This is a single-lined spectroscopic binary, with the presence of a companion being revealed by Doppler shifts in the spectrum.[8] An initial orbital solution for the data gives an orbital period of 220.4 days.[6] The primary is a giant star with a stellar classification of B8 IIIp Mn:Hg:.[3] It is a candidate mercury-manganese star, showing a surfeit of these elements in the spectrum.[8] With five times the Sun's mass, this star is radiating 1,035[7] times as much luminosity from its outer atmosphere at an effective temperature of 12,593 K.[8] This heat gives it the blue-white hue of a B-type star.[11] The companion may be a variable star.[12]