Rho Aquarii
Star in the constellation Aquarius
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Rho Aquarii is a binary star[10] system in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinized from ρ Aquarii, and abbreviated Rho Aqr or ρ Aqr. This system is visible to the naked eye as a point of light with an apparent visual magnitude of +5.34.[3] Based upon parallax measurements, this star is located at a distance of approximately 750 light-years (230 parsecs) from the Sun.[2] It is drifting closer with a radial velocity of –9 km/s.[5] The position of this star near the ecliptic means it is subject to lunar occultations.[11]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Aquarius[1] |
| Right ascension | 22h 20m 11.917s[2] |
| Declination | −07° 49′ 15.97″[2] |
| Apparent magnitude (V) | +5.34[3] |
| Characteristics | |
| Spectral type | B8 IIIp Mn:Hg:[4] |
| U−B color index | −0.358[3] |
| B−V color index | −0.057[3] |
| Astrometry | |
| Radial velocity (Rv) | −9[5] km/s |
| Proper motion (μ) | RA: +14.803 mas/yr[2] Dec.: +0.472 mas/yr[2] |
| Parallax (π) | 4.3443±0.1468 mas[2] |
| Distance | 750 ± 30 ly (230 ± 8 pc) |
| Absolute magnitude (MV) | −1.78[1] |
| Orbit[6] | |
| Period (P) | 220.41±0.10 d |
| Eccentricity (e) | 0 (assumed) |
| Periastron epoch (T) | 2418548.7±7.4 JD |
| Semi-amplitude (K1) (primary) | 18.66±2.75 km/s |
| Details | |
| A | |
| Mass | 4.63±0.25[7] M☉ |
| Radius | 5.5[8] R☉ |
| Luminosity | 1,023+357 −264[7] L☉ |
| Surface gravity (log g) | 3.5[8] cgs |
| Temperature | 12,454±152[7] K |
| Metallicity [Fe/H] | 0.059[8] dex |
| Rotation | 6.5633±0.0063 d[7] |
| Rotational velocity (v sin i) | 65.0±6.9[7] km/s |
| Other designations | |
| ρ Aqr, 46 Aquarii, BD−08 5855, GC 31225, HD 211838, HIP 110273, HR 8512, SAO 146023, PPM 206239[9] | |
| 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.[10] An initial orbital solution for the data gives a period of 220.4 days with a circular orbit.[6]
The primary is a non-magnetic chemically peculiar star with a stellar classification of B8 IIIp Mn:Hg:.[4] It is a candidate mercury-manganese star, showing a surfeit of these elements in the spectrum.[10] At least two pulsation periods have been detected; the first is characteristic of a Delta Scuti variable and the second of a Gamma Doradus variable, suggesting this is a hybrid pulsator.[7] The dominant pulsation period is 1.1203±0.0002 d.[12] With 4.63 times the Sun's mass, this star is radiating 1,023 times as much luminosity from its outer atmosphere at an effective temperature of 12,454 K.[7] This heat gives it the blue-white hue of a B-type star.[13] It is spinning with a rotation period of 6.5633±0.0063 d.[7] The primary does not display photometric variability, but the companion may be a variable star.[14] Although no specific age estimates have been published for this star, it is likely to be less than 50 million years old.[15]