104 Aquarii

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104 Aquarii
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension  23h 41m 45.80579s[1]
Declination –17° 48′ 59.5175″[1]
Apparent magnitude (V) 4.83[2]
Right ascension  23h 41m 46.37788s[1]
Declination –17° 47′ 00.7237″[1]
Apparent magnitude (V) 8.54[2]
Spectral type G2 Ib/II[3]
U−B color index +0.49[2]
B−V color index +0.82[2]
Spectral type A5/7 (V)[3]
B−V color index +0.15[2]
Radial velocity (Rv)+6.52±0.15[4] km/s
Proper motion (μ) RA: +14.872[1] mas/yr
Dec.: +0.862[1] mas/yr
Parallax (π)4.5774 ± 0.1882[1] mas
Distance710 ± 30 ly
(218 ± 9 pc)
Absolute magnitude (MV)–2.49[4]
Proper motion (μ) RA: –27.214[1] mas/yr
Dec.: –28.539[1] mas/yr
Parallax (π)3.2221 ± 0.0487[1] mas
Distance1,010 ± 20 ly
(310 ± 5 pc)
104 Aqr A
Mass4.23[5] M
Radius31.9±2.3[4] R
Luminosity447[5] L
Surface gravity (log g)2.20[4] cgs
Temperature5,444±14[4] K
Metallicity [Fe/H]+0.05[6] dex
Rotational velocity (v sin i)15[7] km/s
Age135[5] Myr
Other designations
HR 8982, SAO 165836.[8]
A: BD −18 6358, HD 222574, HIP 116901
B: BD −18 6359, HD 222561, HIP 116904
Database references

104 Aquarii (abbreviated 104 Aqr) is a star in the equatorial constellation of Aquarius. 104 Aquarii is the Flamsteed designation, although it also bears the Bayer designation A2 Aquarii. Based on an annual parallax shift of only 3.89 ± 0.25 milliarcseconds, the distance to this star is about 840 light-years (260 parsecs).[9] At that range, the brightness of the star in the V-band is reduced by 0.10 magnitudes as a result of extinction caused by intervening gas and dust.[5]

This is a double star and possible binary system;[10] the primary component has a stellar classification of G2 Ib/II,[3] which places it on the borderline between the bright giant and lower luminosity supergiant stars. It has passed the first dredge-up and may be undergoind Cepheid-like pulsations.[4] With more than four times the mass of the Sun,[5] this is an evolved star that has reached its current stage after only 135 million years,[5] it has expanded to around 51–88[11] times the Sun's radius and is radiating 447–fold[5] the luminosity of the Sun. This energy is being emitted from its outer atmosphere at an effective temperature of 5,478 K,[6] giving it the golden-hued glow of a G-type star,[12] it is a suspected variable star.[13]

The companion is a magnitude 7.9 star with an angular separation of 120.1 arcseconds from the primary.[10]


  1. ^ a b c d e f g h i j Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
  2. ^ a b c d e Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. ^ a b c Houk, N.; Smith-Moore, M. (1988). "Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0". Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4. Bibcode:1988mcts.book.....H.
  4. ^ a b c d e f Usenko, I. A.; et al. (November 2015), "Spectroscopic studies of four southern-hemisphere G-K supergiants: HD 192876 (α1 Cap), HD 194215 (HR 7801), HD 206834 (c Cap), and HD 222574 (104 Aqr)", Astronomy Letters, 41 (11): 660–676, Bibcode:2015AstL...41..660U, doi:10.1134/S1063773715110067.
  5. ^ a b c d e f g Takeda, Yoichi; Sato, Bun'ei; Murata, Daisuke (2008), "Stellar Parameters and Elemental Abundances of Late-G Giants", Publications of the Astronomical Society of Japan, 60 (4): 781–802, arXiv:0805.2434, Bibcode:2008PASJ...60..781T, doi:10.1093/pasj/60.4.781.
  6. ^ a b Luck, R. E.; Bond, H. E. (October 1980), "The chemical compositions of 26 distant late-type supergiants and the metallicity gradient in the galactic disk", Astrophysical Journal, Part 1, 241: 218–228, Bibcode:1980ApJ...241..218L, doi:10.1086/158334.
  7. ^ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1), Bibcode:1970CoAsi.239....1B.
  8. ^ "104 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-16.
  9. ^ 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.
  10. ^ a b Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  11. ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  12. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16.
  13. ^ Demartino, Robert; et al. (April 1996), "Accurate Positions Of Suspected Variable Stars Near The South Galactic Pole", Information Bulletin on Variable Stars, 4322: 1, Bibcode:1996IBVS.4322....1D.

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