88 Aquarii

88 Aquarii (abbreviated 88 Aqr) is a star in the equatorial constellation of Aquarius. 88 Aquarii is the Flamsteed designation, though it also bears the Bayer designation c2 Aquarii. In dark conditions it is visible to the naked eye with an apparent visual magnitude of +3.68.[2] Based upon parallax measurements, this star is at a distance of around 271 light-years (83 parsecs) from Earth.[1]

This article is about c2 Aquarii. For other star systems with this Bayer designation, see c Aquarii.
88 Aquarii
Diagram showing star positions and boundaries of the Aquarius constellation and its surroundings
Location of 88 Aquarii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Aquarius
Right ascension 23h 09m 26.79681s[1]
Declination –21° 10′ 20.6812″[1]
Apparent magnitude (V) +3.679[2]
Characteristics
Spectral type K1 III[3]
U−B color index +1.239[2]
B−V color index +1.215[2]
Astrometry
Radial velocity (Rv)+21.1[4] km/s
Proper motion (μ) RA: +55.40[1] mas/yr
Dec.: +30.49[1] mas/yr
Parallax (π)12.05 ± 0.22 mas[1]
Distance271 ± 5 ly
(83 ± 2 pc)
Details
Radius29[5] R☉
Surface gravity (log g)2.34[6] cgs
Temperature4,430[6] K
Metallicity [Fe/H]–0.24[6] dex
Other designations
BD-21°6368, FK5 873, HD 218594, HIP 114341, HR 8812, SAO 191683.[7]
Database references
SIMBADdata

The spectrum of 88 Aquarii matches an evolved giant star with a classification of K1 III.[3] Its measured angular diameter is 3.24 ± 0.20 mas,[8] which, at the estimated distance of Delta Ophiuchi,[1] yields a physical size of about 29 times the radius of the Sun.[5] The cool, orange hued glow of this star comes from the outer atmosphere's effective temperature of 4,430 K.[6]

References
  1. 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, S2CID 18759600.
  2. Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publications of the Department of Astronomy University of Chile, Publicaciones Universidad de Chile, Department de Astronomy, 1: 1–17, Bibcode:1966PDAUC...1....1G.
  3. Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1988mcts.book.....H.
  4. Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg, Astronomisches Rechen-Institut Heidelberg, 35 (35): 1, Bibcode:1999VeARI..35....1W.
  5. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
  6. McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527.
  7. "* 88 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-13.
  8. Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039
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