Kappa_Aquarii
Kappa Aquarii
Star in the constellation Aquarius
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]
| 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] |
| Distance | 214 ± 3 ly (65.6 ± 0.9 pc) |
| Absolute magnitude (MV) | +0.96[5] |
| Details | |
| 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 | |
| Database references | |
| SIMBAD | data |
The two components are designated Kappa Aquarii A (formally named Situla /ˈsɪtjuːlə/, the traditional name for the system)[7] and B.
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.
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]
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]
- 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.
- 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.
- Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B.
- 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.
- "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].
- 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.
- "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.