Kappa Aquarii

κ Aquarii
	Location of κ Aquarii (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Aquarius
Right ascension	22h 37m 45.38049s
Declination	−04° 13′ 40.9939″
Apparent magnitude (V)	5.03
Characteristics
Spectral type	K2 III
U−B color index	+1.16
B−V color index	+1.142
Astrometry
Radial velocity (Rv)	+7.31 ± 0.16 km/s
Proper motion (μ)	RA: −69.23 mas/yr ; Dec.: −119.67 mas/yr
Parallax (π)	15.25 ± 0.21 mas
Distance	214 ± 3 ly ; (65.6 ± 0.9 pc)
Absolute magnitude (MV)	+0.96
Details
Radius	13 R☉
Luminosity	60 L☉
Surface gravity (log g)	2.5 cgs
Temperature	4,581 K
Metallicity [Fe/H]	+0.14 dex
Rotational velocity (v sin i)	3.8 km/s
Other designations
	Situla, 63 Aquarii, BD-04 5716, FK5 1595, HD 214376, HIP 111710, HR 8610, SAO 146210
Database references
SIMBAD	data

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]

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

^ ^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, S2CID 18759600.
^ ^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.
^ ^a ^b Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B.
^ ^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, S2CID 121883397.
^ 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.
^ "kap Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-01.
^ ^a ^b "Naming Stars". IAU.org. Retrieved 16 December 2017.
^ 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].
^ ^a ^b Allen, Richard Hinckley, Star Names — Their Lore and Meaning: Aquarius (Dover ed.), retrieved 2012-07-01.
^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
^ (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.
^ (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.
^ 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.
^ ^a ^b "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.
^ LacusCurtius • Allen's Star Names — Aquarius

External links

Image κ Aquarii

[aaa474_2_653-1] 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.

[aass34_1-2] 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.

[msom1962-3] Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B.

[aj135_1_209-4] ^ ^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, S2CID 121883397.

[Anderson2012-5] 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.

[SIMBAD-6] "kap Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-01.

[IAU-LSN-7] "Naming Stars". IAU.org. Retrieved 16 December 2017.

[planetnaming-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].

[allen1963-9] Allen, Richard Hinckley, Star Names — Their Lore and Meaning: Aquarius (Dover ed.), retrieved 2012-07-01.

[WGSN-10] IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.

[TriRpt18-11] "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.

[mnras389_2_869-14] 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.

[csiro-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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