Epoch J2000 Equinox J2000
|Right ascension||17h 53m 31.72962s|
|Declination||+56° 52′ 21.5143″|
|Apparent magnitude (V)||3.75|
|Spectral type||K2 III|
|U−B color index||+1.21|
|B−V color index||+1.18|
|Radial velocity (Rv)||-26.38 ± 0.20 km/s|
|Proper motion (μ)|| RA: 93.82 ± 0.14 mas/yr |
Dec.: 78.50 ± 0.12 mas/yr
|Parallax (π)||28.98 ± 0.12 mas|
|Distance||112.5 ± 0.5 ly |
(34.5 ± 0.1 pc)
|Absolute magnitude (MV)||+1.06|
|Mass||1.45 ± 0.17 M☉|
|Luminosity||49 ± 4 L☉|
|Surface gravity (log g)||2.3 cgs|
|Metallicity [Fe/H]||–0.09 dex|
|Rotational velocity (v sin i)||2.3 km/s|
Xi Draconis (ξ Draconis, abbreviated Xi Dra, ξ Dra) is a double or binary star in the northern circumpolar constellation of Draco. It has an apparent visual magnitude of 3.75. Based upon parallax measurements, it is located at a distance of 112.5 light-years (34.5 parsecs) from the Sun. At this distance, the apparent magnitude is diminished by 0.03 from extinction caused by intervening gas and dust.
ξ Draconis (Latinised to Xi Draconis) is the system's Bayer designation. The designations of the two components as Xi Draconis 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).
It bore the traditional names Grumium. This is a graphic corruption of the Latin Grunnum 'snout', as Ptolemy had described this star as being on the jawbone of the dragon. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Grumium for the component Xi Draconis A on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
This star was also known as Nodus I or Nodus Primus. Along with Beta Draconis (Rastaban), Gamma Draconis (Eltanin), Mu Draconis (Erakis) and Nu Draconis (Kuma), it was one of Al ʽAwāyd "the Mother Camels", which were later known as the Quinque Dromedarii.
In Chinese, 天棓 (Tiān Bàng), meaning Celestial Flail, refers to an asterism consisting of Xi Draconis, Nu Draconis, Beta Draconis, Gamma Draconis and Iota Herculis. Consequently, the Chinese name for Xi Draconis itself is 天棓一 (Tiān Bàng yī, English: the First Star of Celestial Flail).
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- ‹See Tfd›(in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived January 30, 2011, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
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