Mu Draconis

Mu Draconis (μ Draconis, abbreviated Mu Dra, μ Dra) is a multiple star system near the head of the constellation of Draco. With a combined magnitude of 4.92, it is visible to the naked eye. Based on parallax estimates by the Hipparcos spacecraft, it is located approximately 89 light-years from the Sun.
The system consists of a single primary star (designated Mu Draconis A, officially named Alrakis from the traditional name of the system), a secondary binary pair (Mu Draconis B) and a further single star (C). B's two components are designated Mu Draconis Ba and Bb.
Mu Draconis A and Ba are nearly identical F-type main-sequence stars, with masses of and , respectively. Both have the spectral class of F5V, and have similar apparent magnitude, at 5.66 and 5.69, respectively. The secondary, Mu Draconis B, has a drifting radial velocity, and is itself a spectroscopic binary with an orbital period of 2,270 days. The smaller component, Mu Draconis Bb, has a mass of . Mu Draconis C is a 14th magnitude common-proper-motion companion 13.2" away from the bright pair, with a mass of .
Nomenclature.
μ Draconis (Latinised to "Mu Draconis") is the star's Bayer designation. The designations of the three constituents as "Mu Draconis A", "B" and "C", and those of "B's" components - "Mu Draconis Ba" and "Bb" - 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 name "Arrakis" (or "Errakis"), which derives from name given to it by Arabian stargazers, الراقص "al-rāqiṣ" "the trotting (camel)" (lit. "the dancing one".
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 "Alrakis" for the component Mu Draconis A on February 1, 2017 and it is now so included in the List of IAU-approved Star Names.
This star, along with Beta Draconis (Rastaban), Gamma Draconis (Eltanin), Nu Draconis ('Kuma') and Xi Draconis (Grumium) were "Al ʽAwāïd", the Mother Camels, which were known in Latin as the Quinque Dromedarii.
Cultural references.
Science fiction writer Frank Herbert chose Arrakis as the name of the primary planet of Canopus (α Carinae) in his "Dune" series of novels, aware that the word "Arrakis" is the transliteration into English of the Arabic words for "the Dancer" (al-Raqis).