Rho Aquarii

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Rho Aquarii
Diagram showing star positions and boundaries of the Aquarius constellation and its surroundings
Cercle rouge 100%.svg

Location of ρ Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 22h 20m 11.91628s[1]
Declination –07° 49′ 15.9649″[1]
Apparent magnitude (V) +5.34[2]
Spectral type B8 IIIp Mn:Hg:[3]
U−B color index –0.358[2]
B−V color index –0.057[2]
Radial velocity (Rv) –9[4] km/s
Proper motion (μ) RA: +14.75[1] mas/yr
Dec.: +1.84[1] mas/yr
Parallax (π) 3.70 ± 0.38[1] mas
Distance approx. 880 ly
(approx. 270 pc)
Mass 5.00 ± 0.22[5] M
Luminosity 1,035[5] L
Temperature 12,593[6] K
Rotational velocity (v sin i) 65[3] km/s
Other designations
46 Aquarii, BD–08 5855, HD 211838, HIP 110273, HR 8512, SAO 146023.[7]
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

Rho Aquarii (ρ Aqr, ρ Aquarii) is the Bayer designation for a binary star 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 made during the Hipparcos mission, this star is at a distance of roughly 880 light-years (270 parsecs) from Earth.[1]

This is a single-lined spectroscopic binary, with the presence of a companion being revealed by Doppler shifts in the spectrum.[6] The primary is a giant star with a stellar classification of B8 IIIp Mn:Hg:.[3] It is a Mercury-Manganese star, showing a surfeit of these elements in the spectrum.[6] With five times the Sun's mass, this star is radiating 1,035[5] times as much luminosity from its outer atmosphere at an effective temperature of 12,593 K.[6] This heat gives it the blue-white hue of a B-type star.[8] The companion may be a variable star.[9]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752free to read, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Cousins, A. W. J. (1984), "Standardization of Broadband Photometry of Equatorial Standards", South African Astronomical Observatory Circulars, 8: 59, Bibcode:1984SAAOC...8...59C. 
  3. ^ a b c Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590. 
  4. ^ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W. 
  5. ^ a b c Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335free to read, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355. 
  6. ^ a b c d Makaganiuk, V.; et al. (January 2011), "The search for magnetic fields in mercury-manganese stars", Astronomy and Astrophysics, 525: A97, arXiv:1010.3931free to read, Bibcode:2011A&A...525A..97M, doi:10.1051/0004-6361/201015666. 
  7. ^ "rho Aqr -- Star", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-04. 
  8. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16 
  9. ^ Adelman, S. J.; Young, K. J. (January 2005), "uvby FCAPT photometry of the mCP stars HR 2258, MW Vul, and HR 9017 and the HgMn star 46 ρ Aqr", Astronomy and Astrophysics, 429: 317–322, Bibcode:2005A&A...429..317A, doi:10.1051/0004-6361:20041118. 

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