1 Aquarii

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1 Aquarii
Aquarius constellation map.svg
Red circle.svg

Location of 1 Aqr (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 20h 39m 24.8915s[1]
Declination +00° 29′ 11.201″[1]
Apparent magnitude (V) 5.16[2]
Spectral type K1III[2]
U−B color index +0.97[citation needed]
B−V color index +1.06[2]
Radial velocity (Rv) −42.81[3] km/s
Proper motion (μ) RA: 101.95[1] mas/yr
Dec.: −20.50[1] mas/yr
Parallax (π) 13.99 ± 0.65 mas
Distance 230 ± 10 ly
(71 ± 3 pc)
Absolute magnitude (MV) 0.77[4]
Temperature 3,500–5,000[citation needed] K
Metallicity −0.12[4]
Rotation 1.8[4]
Age ~5 × 109[citation needed] years
Other designations
HR 7897, HD 196758, SAO 126062, BD +0 4064, FK5 3651, WDS J20394+0029, CCDM J20394+0029
Database references
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

1 Aquarii (abbreviated 1 Aqr) is a multiple star in the constellation Aquarius. 1 Aquarii is the Flamsteed designation. It is a K-class giant of the spectral type K1III. Its companions, B and C, are optical and have no physical relation to 1 Aqr A. 1 Aquarii is known to be an infra-red source.


NAME Right ascension Declination Apparent magnitude (V) Database references
1 Aquarii B (BD-00 4064B) 20h 39m 21.8s +00° 28' 25 11.5 Simbad
1 Aquarii C (BD-00 4064C) 20h 39m 27.1s +00° 30' 07 11.3 Simbad


  1. ^ a b c d Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752free to read. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Hoffleit, Dorrit; Jaschek, Carlos (1991). "The Bright star catalogue". New Haven. Bibcode:1991bsc..book.....H. 
  3. ^ Massarotti, Alessandro; Latham, David W.; Stefanik, Robert P.; Fogel, Jeffrey (2008). "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity". The Astronomical Journal. 135: 209. Bibcode:2008AJ....135..209M. doi:10.1088/0004-6256/135/1/209. 
  4. ^ a b c Pace, G.; Pasquini, L.; Ortolani, S. (2003). "The Wilson-Bappu effect: A tool to determine stellar distances". Astronomy and Astrophysics. 401 (3): 997. arXiv:astro-ph/0301637free to read. Bibcode:2003A&A...401..997P. doi:10.1051/0004-6361:20030163.