Kappa Aquarii

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

Location of ι 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]
Spectral type K2 III[3]
U−B color index +1.16[2]
B−V color index +1.142[4]
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[1] mas
Distance 214 ± 3 ly
(65.6 ± 0.9 pc)
Radius 13[4] R
Luminosity 60[4] L
Surface gravity (log g) 2.5[4] cgs
Temperature 4,581[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.[5]

Kappa Aquarii (κ Aqr, κ Aquarii) is the Bayer designation for a double star in the equatorial constellation of Aquarius. It has the traditional name Situla, a Latin word meaning "bucket" or "water jar".[6] 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, the distance to Kappa Aquarii is around 214 light-years (66 parsecs).[2]

This is most probably a wide binary star system.[7] 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. Kappa Aquarii 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.[8]

The fainter companion star is located at an angular separation of 98.3 arcseconds and has an apparent magnitude of 8.8.[8]

In culture[edit]

In Chinese, 虛梁 (Xū Liáng), meaning Temple, refers to an asterism consisting of κ Aquarii, 44 Aquarii, 51 Aquarii and HD 216718.[9] Consequently, κ Aquarii itself is known as 虛梁三 (Xū Liáng sān, English: the Third Star of Temple.).[10] From this Chinese name, the name Heu Leang was appeared, meaning "the empty bridge".[6]

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

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.[11]

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


  1. ^ a b c d e 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. ^ 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 Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram 4, Bibcode:1962MtSOM...4....1B. 
  4. ^ a b c d e f g h i j k 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. 
  5. ^ "kap Aqr -- Star in double system", SIMBAD Astronomical Object Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-07-01. 
  6. ^ a b Allen, Richard Hinckley, Star Names — Their Lore and Meaning: Aquarius (Dover ed.), retrieved 2012-07-01. 
  7. ^ 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. 
  8. ^ a b "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16. 
  9. ^ (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.
  10. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  11. ^ LacusCurtius • Allen's Star Names — Aquarius

External links[edit]