Xi Draconis (ξ Draconis, abbreviated Xi Dra, ξ Dra) is a

double Double, The Double or Dubble may refer to: Mathematics and computing * Multiplication by 2 * Double precision, a floating-point representation of numbers that is typically 64 bits in length * A double number of the form x+yj, where j^2=+1 * A ...

binary star A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...

in the northern

circumpolar constellation A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest p ...

of Draco. It has an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light ca ...

of 3.75. Based upon

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements, it is located at a distance of from the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

. At this distance, the apparent magnitude is diminished by 0.03 from

extinction Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

caused by intervening gas and dust. The two components are designated Xi Draconis A (officially named Grumium , a traditional name for the system) and B.

Nomenclature

''ξ Draconis'' ( Latinised to ''Xi Draconis'') is the system's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...

. 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 system A star system or stellar system is a small number of stars that orbit each other, bound by gravity, gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally calle ...

s, and adopted by the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

(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

organized a

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(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 Mu Draconis (μ Draconis, abbreviated Mu Dra, μ Dra) is a multiple star system near the head of the constellation of Draco (constellation), Draco. With a combined magnitude (astronomy), magnitude of 4.92, it is visible to the ...

(Erakis) and Nu Draconis (Kuma), it was one of ''Al ʽAwāyd'' "the Mother Camels", which were later known as the ''Quinque Dromedarii''. In Chinese, (), meaning '' Celestial Flail'', refers to an asterism consisting of Xi Draconis, Nu Draconis, Beta Draconis, Gamma Draconis and Iota Herculis. Consequently, the

Chinese name Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethni ...

for Xi Draconis itself is (, ).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.

Namesake

USS ''Grumium'' (AK-112) was a

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

''Crater''-class cargo ship named after the star.

Properties

Xi Draconis A is of

spectral class In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

K2-III. It is not known for certain if Xi Draconis A is on the

red giant branch The red-giant branch (RGB), sometimes called the first giant branch, is the portion of the giant branch before helium ignition occurs in the course of stellar evolution. It is a stage that follows the main sequence for low- to intermediate-mass st ...

, fusing hydrogen into helium in a shell surrounding an inert helium core, or on the

horizontal branch The horizontal branch (HB) is a stage of stellar evolution that immediately follows the red-giant branch in stars whose masses are similar to the Sun's. Horizontal-branch stars are powered by helium fusion in the core (via the triple-alpha proc ...

fusing helium into carbon. The possible companion, Xi Draconis B, is a 16th-magnitude star 316

arcseconds A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

away but, most likely, the pairing is just a line-of-sight coincidence.

References

{{DEFAULTSORT:Xi Draconis Draco (constellation) Draconis, Xi Grumium K-type giants 087585 Draconis, 32 6688 163588 Durchmusterung objects