Mu Draconis

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μ Draconis
Location of μ Draconis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Draco
Right ascension 17h 05m 20.12403s[1]
Declination +54° 28′ 12.0994″[1]
Apparent magnitude (V) 4.92[2]
(5.66 / 5.69)[3]
Characteristics
Spectral type F7V
U−B color index −0.01[4]
B−V color index +0.47[4]
Distance
89 ± 1 ly
(27.4 ± 0.3 pc)
Absolute magnitude (MV)+2.73[6]
Argument of periastron
(ω)
(secondary)		193.31 ± 0.083°
Details
μ Dra A
Gyr
HD
 154905
Database references
SIMBADμ Dra
μ Dra A
μ Dra B

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,[2] 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.[1]

The system consists of a single primary star (designated Mu Draconis A, officially named Alrakis /ælˈreɪkɪs/ from the traditional name of the system),[8][9] 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

spectroscopic binary with an orbital period of 2,270 days.[10] The distance between both stars is 2 arcseconds, so a telescope with a diameter of at least 6 centimetres is necessary to see them separate. The smaller component, Mu Draconis Bb, has a mass of 0.2 M☉. Mu Draconis C is a 14th magnitude common-proper-motion companion 13.2" away from the bright pair, with a mass of 0.29 M☉.[7]

Nomenclature

μ Draconis in optical light

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).[11]

It is also known by the name Arrakis (or Errakis), which is derived from the name given to it by

Arabian stargazers, الراقص al-rāqiṣ "the trotting (camel)" (lit. "the dancing one").[12][13]

In 2016, the

multiple systems.[15] 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.[9]

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.[16]

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).[17]

References

  1. ^
    S2CID 18759600
    .
  2. ^ a b "* mu Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 16 May 2017.
  3. ^ a b c "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 1 August 2017. Retrieved 16 May 2017.
  4. ^
    Bibcode:1986EgUBV........0M
    .
  5. S2CID 119054949
    .
  6. ^
    S2CID 118577511
    .
  7. ^
    S2CID 56066740
    .
  8. ISBN 978-1-931559-44-7
    .
  9. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
  10. S2CID 119387088. (SB9 catalog entry
    )
  11. arXiv:1012.0707 [astro-ph.SR
    ].
  12. ISBN 978-1-931559-44-7
    .
  13. ISBN 978-0-486-21079-7
    .
  14. ^ "International Astronomical Union | IAU". www.iau.org. Retrieved 2017-03-31.
  15. ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  16. ISBN 978-0-486-21079-7
    . Retrieved 2010-12-12.
  17. ISBN 978-1-4766-6960-1
    .


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