108 Aquarii

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108 Aquarii
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension  23h 51m 21.33832s[1]
Declination –18° 54′ 32.9937″[1]
Apparent magnitude (V) 5.194[2]
Spectral type A0VpSiSr[3]
U−B color index –0.396[2]
B−V color index –0.135[2]
Variable type α² CVn[4]
Radial velocity (Rv)+12.7[5] km/s
Proper motion (μ) RA: +26.82[1] mas/yr
Dec.: –4.27[1] mas/yr
Parallax (π)10.23 ± 0.31[1] mas
Distance319 ± 10 ly
(98 ± 3 pc)
Absolute magnitude (MV)+0.08[6]
Mass3.21 ± 0.15[6] M
Radius2.5 ± 0.3[6] R
Luminosity132[6] L
Surface gravity (log g)4.27 ± 0.10[6] cgs
Temperature12,274[6] K
Metallicity [Fe/H]+0.90[7] dex
Rotation3.74 days[6]
Rotational velocity (v sin i)30[8] km/s
Other designations
BD−19°6522, HD 223640, HIP 117629, HR 9031, SAO 165918[4]
Database references

108 Aquarii (abbreviated 108 Aqr) is a star in the equatorial constellation of Aquarius. 108 Aquarii is the Flamsteed designation, although it also bears the Bayer designation i3 Aquarii and the variable star designation ET Aquarii. It has an apparent visual magnitude of 5.194[2] and can be seen with the naked eye under suitably dark skies. Based upon an annual parallax shift of 10.23[1] (with a 3% margin of error), the distance to this star is 319 light-years (98 parsecs).

This is an Ap star; meaning it has a peculiar spectrum that shows an overabundance of certain elements. It has more than three times the mass of the Sun and is 2.5 times the Sun's radius.[6] 108 Aquarii is radiating 132[6] times the luminosity of the Sun from its outer atmosphere at an effective temperature of 12,274 K.[6] At this heat, the star has the white hue of an A-type 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:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ^ a b c d Gutierrez-Moreno, Adelina; et al. (1966), A System of photometric standards, 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G.
  3. ^ Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", The Astrophysical Journal Supplement Series, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182
  4. ^ a b "* i03 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-15.
  5. ^ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W.
  6. ^ a b c d e f g h i j North, P. (June 1998), "Do SI stars undergo any rotational braking?", Astronomy and Astrophysics, 334: 181–187, arXiv:astro-ph/9802286, Bibcode:1998A&A...334..181N.
  7. ^ Vilhu, O.; Tuominen, I. V.; Boyarchuk, A. A. (1976), "Abundance Studies of Peculiar B Stars", in Weiss, W. W.; Jenkner, H.; Wood, H. J. (eds.), Physics of Ap Stars, Proceedings of IAU Colloq. 32, held in Vienna, Austria, 8-11 September, 1976, Universitatssternwarte Wien, p. 563, Bibcode:1976paps.coll..563V.
  8. ^ 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.
  9. ^ Przybylski, A.; Kennedy, P. M. (1965), "Radial velocities and three-colour photometry of 166 southern stars", Monthly Notices of the Royal Astronomical Society, 131: 95–104, Bibcode:1965MNRAS.131...95P, doi:10.1093/mnras/131.1.95.

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