Iota Aquarii

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

Location of ι Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 22h 06m 26.22742s[1]
Declination –13° 52′ 10.8615″[1]
Apparent magnitude (V) 4.279[2]
Spectral type B8 V[3]
U−B color index –0.288[2]
B−V color index –0.062[2]
Radial velocity (Rv) –10.0[4] km/s
Proper motion (μ) RA: +36.89[1] mas/yr
Dec.: –58.99[1] mas/yr
Parallax (π) 18.62 ± 0.22[1] mas
Distance 175 ± 2 ly
(53.7 ± 0.6 pc)
Radius 2.7[5] R
Surface gravity (log g) 4.09 ± 0.08[6] cgs
Temperature 11,284 ± 284[5] K
Metallicity [Fe/H] –0.08 ± 0.12[6] dex
Rotational velocity (v sin i) 135[7] km/s
Age 30–60[8] Myr
Other designations
33 Aquarii, BD–14 6209, FK5 828, HD 209819, HIP 109139, HR 8418, SAO 164861.[9]
Database references

Iota Aquarii (ι Aqr, ι Aquarii) is the Bayer designation for a star in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent magnitude of +4.279.[2] Based upon parallax measurements made during the Hipparcos mission, the distance to this star is around 175 light-years (54 parsecs).[2]

The spectrum of this star fits a stellar classification of B8 V,[3] showing that this is a B-type main sequence star. It has 2.7[5] times the radius of the Sun and is spinning rapidly with a projected rotational velocity of 135 km/s.[7] A 2010 infrared search for companions around this star was unsuccessful.[8]


  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d e Kozok, J. R. (September 1985), "Photometric observations of emission B-stars in the southern Milky Way", Astronomy and Astrophysics Supplement Series, 61: 387–405, Bibcode:1985A&AS...61..387K. 
  3. ^ a b Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, 
  4. ^ Wielen, R.; et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W. 
  5. ^ a b c Underhill, A. B.; et al. (November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars", Monthly Notices of the Royal Astronomical Society, 189: 601–605, Bibcode:1979MNRAS.189..601U, doi:10.1093/mnras/189.3.601. 
  6. ^ a b Wu, Yue; et al. (January 2011), "Coudé-feed stellar spectral library - atmospheric parameters", Astronomy and Astrophysics, 525: A71, arXiv:1009.1491Freely accessible, Bibcode:2011A&A...525A..71W, doi:10.1051/0004-6361/201015014. 
  7. ^ a b 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. 
  8. ^ a b Ehrenreich, D.; et al. (November 2010), "Deep infrared imaging of close companions to austral A- and F-type stars", Astronomy and Astrophysics, 523: A73, arXiv:1007.0002Freely accessible, Bibcode:2010A&A...523A..73E, doi:10.1051/0004-6361/201014763. 
  9. ^ "iot Aqr -- Star", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-06-30. 

External links[edit]