Chi Aquarii

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

Location of χ Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 23h 16m 50.93916s[1]
Declination −07° 43′ 35.4023″[1]
Apparent magnitude (V) +5.06[2]
Spectral type M3 III[3]
U−B color index +1.60[2]
B−V color index +1.60[2]
Variable type SRb?[4]
Radial velocity (Rv) –13.72 ± 0.86[5] km/s
Proper motion (μ) RA: −19.18[1] mas/yr
Dec.: −14.10[1] mas/yr
Parallax (π) 5.32 ± 0.37[1] mas
Distance 610 ± 40 ly
(190 ± 10 pc)
Radius 137[6] R
Other designations
92 Aquarii, BD−08 6076, HD 219576, HIP 114939, HR 8850, SAO 146612.[7]
Database references

Chi Aquarii (χ Aqr, χ Aquarii) is the Bayer designation of a star in the equatorial constellation of Aquarius. The distance to this star, based upon parallax measurements with a 7% margin of error, is roughly 610 light-years (190 parsecs).[1] It is visible to the naked eye with an apparent visual magnitude of +5.06.[2]

This is a red giant star with a spectral classification of M3 III.[3] The interferometry-measured angular diameter of this star is 6.70 ± 0.15 mas,[8] which, at its estimated distance, equates to a physical radius of about 137 times the radius of the Sun.[6] It is classified as a semi-regular variable star and its brightness varies by an amplitude of 0.0636 in magnitude.[9] The identified pulsation periods are 32.3, 38.5, and 44.9 days.[10]


  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, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series, 34: 1–49, Bibcode:1978A&AS...34....1N. 
  3. ^ a b Crampton, D.; Lloyd Evans, T. (1973), "Spectroscopic observations of M giant stars at the South Galactic Pole", Monthly Notices of the Royal Astronomical Society, 162: 11–15, Bibcode:1973MNRAS.162...11C, doi:10.1093/mnras/162.1.11. 
  4. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S. 
  5. ^ Famaey, B.; et al. (May 2009), "Spectroscopic binaries among Hipparcos M giants. I. Data, orbits, and intrinsic variations", Astronomy and Astrophysics, 498 (2): 627–640, Bibcode:2009A&A...498..627F, arXiv:0901.0934Freely accessible, doi:10.1051/0004-6361/200810698. 
  6. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1 . The radius (R*) is given by:
  7. ^ "chi Aqr -- Semi-regular pulsating Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-05. 
  8. ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039. 
  9. ^ Koen, Chris; Eyer, Laurent (March 2002), "New periodic variables from the Hipparcos epoch photometry", Monthly Notices of the Royal Astronomical Society, 331 (1): 45–59, Bibcode:2002MNRAS.331...45K, arXiv:astro-ph/0112194Freely accessible, doi:10.1046/j.1365-8711.2002.05150.x. 
  10. ^ Tabur, V.; et al. (December 2009), "Long-term photometry and periods for 261 nearby pulsating M giants", Monthly Notices of the Royal Astronomical Society, 400 (4): 1945–1961, Bibcode:2009MNRAS.400.1945T, arXiv:0908.3228Freely accessible, doi:10.1111/j.1365-2966.2009.15588.x. 

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