Kappa Aquarii

Kappa Aquarii (κ Aquarii, abbreviated Kappa Aqr, κ Aqr) is a probable binary star in the equatorial constellation of Aquarius. This system is visible to the naked eye, but it is faint at an apparent magnitude of 5.03.[2] Based upon parallax measurements made during the Hipparcos mission, it is around 214 light-years (66 parsecs) from the Sun.[2]

κ Aquarii
Location of κ Aquarii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 22h 37m 45.38049s[1]
Declination −04° 13′ 40.9939″[1]
Apparent magnitude (V) 5.03[2]
Characteristics
Spectral type K2 III[3]
U−B color index +1.16[2]
B−V color index +1.142[4]
Astrometry
Radial velocity (Rv)+7.31 ± 0.16[4] km/s
Proper motion (μ) RA: −69.23[1] mas/yr
Dec.: −119.67[1] mas/yr
Parallax (π)15.25 ± 0.21 mas[1]
Distance214 ± 3 ly
(65.6 ± 0.9 pc)
Absolute magnitude (MV)+0.96[5]
Details
Radius13[4] R☉
Luminosity60[4] L☉
Surface gravity (log g)2.5[4] cgs
Temperature4,581[4] K
Metallicity [Fe/H]+0.14[4] dex
Rotational velocity (v sin i)3.8[4] km/s
Other designations
Situla, 63 Aquarii, BD-04 5716, FK5 1595, HD 214376, HIP 111710, HR 8610, SAO 146210[6]
Database references
SIMBADdata

The two components are designated Kappa Aquarii A (formally named Situla /ˈsɪtjuːlə/, the traditional name for the system)[7] and B.

Nomenclature

κ Aquarii (Latinised to Kappa Aquarii) is the system's Bayer designation. The designations of the two components as Kappa Aquarii A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[8]

It bore the traditional name Situla, a Latin word meaning "bucket" or "water jar".[9] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[10] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[11] It approved the name Situla for the component Kappa Aquarii A on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.[7]

In Chinese, 虛梁 (Xū Liáng), meaning Temple, refers to an asterism consisting of Kappa Aquarii, 44 Aquarii, 51 Aquarii and HD 216718.[12] Consequently, the Chinese name for Kappa Aquarii itself is 虛梁三 (Xū Liáng sān, English: the Third Star of Temple).[13] From this Chinese name, the name Heu Leang has appeared, meaning "the empty bridge".[9]

Namesake

USS Situla (AK-140) was a United States Navy Crater-class cargo ship named after the star.

Properties

Kappa Aquarii is most probably a wide binary star system.[14] The brighter component is a giant star with a stellar classification of K2 III.[3] It has exhausted the supply of hydrogen at its core and has expanded to 13[4] times the radius of the Sun. It is radiating 60[4] times the Sun's luminosity from its outer envelope at an effective temperature of 4,581 K,[4] giving it the orange-hued glow of a K-type star.[15]

The fainter companion star is located at an angular separation of 98.3 arcseconds and has an apparent magnitude of 8.8.[15]

In culture

Endymion, an 1818 poem by John Keats, describes the star in its form as a water urn thus:

Crystalline brother of the belt of heaven,
Aquarius! to whom King Jove has given
Two liquid pulse streams 'stead of feather'd wings,
Two fan-like fountains, — thine illuminings.[16]

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. 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. Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B.
  4. Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209, S2CID 121883397.
  5. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  6. "kap Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-01.
  7. "Naming Stars". IAU.org. Retrieved 16 December 2017.
  8. Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  9. Allen, Richard Hinckley, Star Names — Their Lore and Meaning: Aquarius (Dover ed.), retrieved 2012-07-01.
  10. IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
  11. "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  12. (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  13. (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2010-08-18 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  14. 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. S2CID 14878976.
  15. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on February 22, 2012, retrieved 2012-01-16.
  16. LacusCurtius • Allen's Star Names — Aquarius
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