Sigma Aquarii

Sigma Aquarii
Diagram showing star positions and boundaries of the Aquarius constellation and its surroundings


Location of σ Aquarii (circled)

Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 22h 30m 38.81546s[1]
Declination –10° 40′ 40.6238″[1]
Apparent magnitude (V) 4.81[2]
Characteristics
Spectral type A0 IVs[3]
U−B color index –0.14[2]
B−V color index –0.08[2]
Astrometry
Radial velocity (Rv)+11[4] km/s
Proper motion (μ) RA: +0.30[1] mas/yr
Dec.: –26.87[1] mas/yr
Parallax (π)11.26 ± 1.26[1] mas
Distanceapprox. 290 ly
(approx. 89 pc)
Absolute magnitude (MV)0.29±0.23[5]
Details
Mass2.72±0.12[5] M☉
Radius2.87[5] R☉
Luminosity79[5] L☉
Surface gravity (log g)3.75[6] cgs
Temperature10,125[6] K
Rotational velocity (v sin i)22[6] km/s
Age30[5] Myr
Other designations
57 Aquarii, BD–11 5850, FK5 1591, HD 213320, HIP 111123, HR 8573, SAO 165134.[7]
Database references
SIMBADdata

Sigma Aquarii (σ Aqr, σ Aquarii) is the Bayer designation for a double star in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent visual magnitude of 4.81.[2] Based upon parallax measurements, the distance to this star is roughly 290 light-years (89 parsecs).[1]

Sigma Aquarii is an astrometric binary with an orbital period of 654 days. The primary component has a stellar classification of A0 IVs,[3] indicating that it is a subgiant star. This is categorized as an Am star, meaning that it is a chemically peculiar. The spectrum displays at least double the normal abundances of elements like magnesium, aluminum and silicon, while helium and scandium are under-abundant.

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752 Freely accessible, doi:10.1051/0004-6361:20078357.
  2. 1 2 3 4 Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
  3. 1 2 Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
  4. ↑ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington D.C., Bibcode:1953GCRV..C......0W.
  5. 1 2 3 4 5 Gerbaldi, M.; et al. (June 1999), "Search for reference A0 dwarf stars: Masses and luminosities revisited with HIPPARCOS parallaxes", Astronomy and Astrophysics Supplement, 137 (2): 273–292, Bibcode:1999A&AS..137..273G, doi:10.1051/aas:1999248.
  6. 1 2 3 Adelman, S. J.; Young, J. M.; Baldwin, H. E. (February 1984), "Optical region elemental abundance analyses of B and A stars. II - The hot AM stars Omicron Pegasi and Sigma Aquarii and the marginal peculiar A star Nu CANCRI", Monthly Notices of the Royal Astronomical Society, 206: 649–660, Bibcode:1984MNRAS.206..649A, doi:10.1093/mnras/206.3.649.
  7. ↑ "sig Aqr -- Star", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-04.
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