Chi Aquarii

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


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]
Characteristics
Spectral type M3 III[3]
U−B color index +1.60[2]
B−V color index +1.60[2]
Variable type Semi-regular[4]
Astrometry
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
Distance610 ± 40 ly
(190 ± 10 pc)
Details
Radius137[6] R☉
Other designations
92 Aquarii, BD−08 6076, HD 219576, HIP 114939, HR 8850, SAO 146612.[7]
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

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.[4]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 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. ↑ 2.0 2.1 2.2 2.3 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. ↑ 3.0 3.1 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.
  4. ↑ 4.0 4.1 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, arXiv:0908.3228, Bibcode:2009MNRAS.400.1945T, doi:10.1111/j.1365-2966.2009.15588.x.
  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, arXiv:0901.0934, Bibcode:2009A&A...498..627F, doi:10.1051/0004-6361/200810698.
  6. ↑ 6.0 6.1 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:
    \begin{align} 2\cdot R_* & = \frac{((190\cdot 6.70\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\ & \approx 274\cdot R_{\bigodot} \end{align}
  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, arXiv:astro-ph/0112194, Bibcode:2002MNRAS.331...45K, doi:10.1046/j.1365-8711.2002.05150.x.

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