| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22h37m 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 | |
Situla, 63 Aquarii, BD-04 5716, FK5 1595, HD 214376, HIP 111710, HR 8610, SAO 146210[6] | |
| Database references | |
| SIMBAD | data |
Kappa Aquarii (κ Aquarii, abbreviated Kappa Aqr, κ Aqr) is a probable binary star in the equatorial constellationofAquarius. 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 (66parsecs) 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.
κ Aquarii (LatinisedtoKappa 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]
InChinese, 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]
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 temperatureof4,581 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]
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