View source for Astronomy:Mu Draconis

{{Short description|Star in the constellation Draco}}
{{Starbox begin
| name=μ Draconis
}}
{{Starbox image
 | image=
{{Location mark
|image=Draco constellation map.svg|alt=|float=center|width=240
|label=|position=right
|mark=Red circle.svg|mark_width=10|mark_link=μ Dra
|x=383|y=935
}}
|caption=Location of μ Draconis (circled)
}}
{{Starbox observe
| epoch=J2000
| ra={{RA|17|05|20.12403}}<ref name=HIP>{{cite journal|title=Validation of the new Hipparcos reduction|url=http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL|author=van Leeuwen, F.|display-authors=0|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|date=2007|arxiv=0708.1752|bibcode=2007A&A...474..653V|doi=10.1051/0004-6361:20078357|s2cid = 18759600}}</ref>
| dec={{DEC|+54|28|12.0994}}<ref name=HIP/>
| appmag_v=4.92<ref name=Simbad>{{cite simbad|title=* mu Dra|access-date=16 May 2017}}</ref><br/>(5.66 / 5.69)<ref name=ORB6/>
| constell=[[Astronomy:Draco (constellation)|Draco]]
}}
{{Starbox character
| class=F7V
| b-v=+0.47<ref name=EgUBV>{{cite journal|author1=Mermilliod, J.-C.|title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)|journal=Catalogue of Eggen's UBV Data|pages=0|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1986EgUBV........0M&db_key=AST&nosetcookie=1|date=1986|bibcode= 1986EgUBV........0M}}</ref>
| u-b=−0.01<ref name=EgUBV/>
| variable=
}}
{{Starbox astrometry
| radial_v=&minus;17.30 ± 0.5<ref>{{cite journal|bibcode=2007A&A...475..519H|doi=10.1051/0004-6361:20077221|arxiv=0707.1891|title=The Geneva-Copenhagen survey of the Solar neighbourhood II|journal=Astronomy and Astrophysics|volume=475|issue=2|pages=519|year=2007|last1=Holmberg|first1=J.|last2=Nordström|first2=B.|last3=Andersen|first3=J.|s2cid=119054949}}</ref>
| prop_mo_ra=&minus;58.16<ref name=HIP/>
| prop_mo_dec=67.87<ref name=HIP/>
| parallax=36.45
| p_error=0.46
| parallax_footnote=<ref name=HIP/>
| absmag_v = +2.73<ref name=holmberg>{{cite journal|bibcode=2009A&A...501..941H|title=The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics|journal=Astronomy and Astrophysics|volume=501|issue=3|pages=941|last1=Holmberg|first1=J.|last2=Nordström|first2=B.|last3=Andersen|first3=J.|year=2009|doi=10.1051/0004-6361/200811191|arxiv = 0811.3982 |s2cid=118577511}}</ref>
}}
{{Starbox orbit
| reference=<ref name=ORB6>{{cite web|url=http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6|title=Sixth Catalog of Orbits of Visual Binary Stars|work=United States Naval Observatory|access-date=16 May 2017|archive-date=1 August 2017|archive-url=https://web.archive.org/web/20170801102553/http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6|url-status=dead}}</ref>
| primary=μ Dra A
| name=μ Dra B
| period=812.0 ± 70.5
| axis=4.48 ± 0.03
| eccentricity=0.5139 ± 0.029
| inclination=142.2 ± 1.3
| node=282.85 ± 0.80
| periastron=1946.19 ± 0.72
| periarg=193.31 ± 0.083
}}
{{Starbox detail
| component1 = μ Dra A
| mass = 1.35<ref name=tokovinin>{{cite journal|bibcode=2014AJ....147...87T|title=From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs|journal=The Astronomical Journal|volume=147|issue=4|pages=87|last1=Tokovinin|first1=Andrei|year=2014|doi=10.1088/0004-6256/147/4/87|arxiv = 1401.6827 |s2cid=56066740}}</ref>
| metal_fe = &minus;0.01<ref name=holmberg/>
| component2 = μ Dra B
| mass2 = 1.30<ref name=tokovinin/>
| age_gyr2 = 2.2<ref name=holmberg/>
}}
{{Starbox catalog
| names=[[Astronomy:Flamsteed designation|21]]&nbsp;Draconis, GJ&nbsp;9584, BD+54°&nbsp;1857, [[Astronomy:Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;30239, HIP&nbsp;83608
| component1=A
| names1=Alrakis, [[Astronomy:Bright Star Catalogue|HR]]&nbsp;6370, HD&nbsp;154906
| component2=B
| names2=[[Astronomy:Bright Star Catalogue|HR]]&nbsp;6369, HD&nbsp;154905
}}
{{Starbox reference
| Simbad = mu+Draconis|sn=μ Dra
| Simbad2 = HD+154906|sn2=μ Dra A
| Simbad3 = HD+154905|sn3=μ Dra B
}}
{{Starbox end}}

'''Mu Draconis''' ('''μ&nbsp;Draconis''', abbreviated '''Mu Dra''', '''μ&nbsp;Dra''') is a multiple star system near the head of the [[Astronomy:Constellation|constellation]] of [[Astronomy:Draco (constellation)|Draco]]. With a combined [[Astronomy:Magnitude|magnitude]] of 4.92,<ref name=Simbad/> it is visible to the naked eye. Based on [[Astronomy:Stellar parallax|parallax]] estimates by the [[Astronomy:Hipparcos|Hipparcos]] spacecraft, it is located approximately 89&nbsp;[[Astronomy:Light-year|light-year]]s from the [[Astronomy:Sun|Sun]].<ref name=HIP/>

The system consists of a single primary star (designated Mu Draconis A, officially named '''Alrakis''' {{IPAc-en|æ|l|'|r|ei|k|I|s}} from the traditional name of the system),<ref name=Kunitzsch>{{cite book
  |last1=Kunitzsch |first1=Paul
  |last2=Smart |first2=Tim
  |date = 2006  |edition = 2nd rev.
  |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations
  |publisher = Sky Pub |location = Cambridge, Massachusetts
  |isbn = 978-1-931559-44-7
}}</ref><ref name="IAU-LSN">{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |access-date=16 December 2017}}</ref> a secondary [[Astronomy:Binary star|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 [[Astronomy:F-type main-sequence star|F-type main-sequence star]]s, with masses of {{solar mass|1.35}} and {{solar mass|1.30}}, respectively.<ref name=tokovinin/> Both have the [[Astronomy:Stellar classification|spectral class]] of F5V, and have similar [[Astronomy:Apparent magnitude|apparent magnitude]], at 5.66 and 5.69, respectively.<ref name=ORB6/> The secondary, Mu Draconis B, has a drifting [[Astronomy:Radial velocity|radial velocity]], and is itself a [[Astronomy:Spectroscopic binary|spectroscopic binary]] with an [[Astronomy:Orbital period|orbital period]] of 2,270 days.<ref name=SB9>{{cite journal|title=S<sub>B<sup>9</sup></sub>: The ninth catalogue of spectroscopic binary orbits|display-authors=1|author1=Pourbaix, D.|author2=Tokovinin, A. A.|author3=Batten, A. H.|author4=Fekel, F. C.|author5=Hartkopf, W. I.|author6=Levato, H.|author7=Morrell, N. I.|author8=Torres, G.|author9=Udry, S.|journal=Astronomy and Astrophysics|volume=424|issue=2|pages=727–732|year=2004|doi=10.1051/0004-6361:20041213|arxiv=astro-ph/0406573|bibcode=2004A&A...424..727P|s2cid=119387088}} ([http://sb9.astro.ulb.ac.be/ProcessMainform.cgi?Catalog=HD&Id=154905&Coord=&Epoch=2000&radius=10&unit=arc+min SB9 catalog entry])</ref> 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 {{solar mass|0.2}}. Mu Draconis C is a 14th magnitude common-proper-motion companion 13.2" away from the bright pair, with a mass of {{solar mass|0.29}}.<ref name=tokovinin/>

== Nomenclature ==

[[Image:Mu Draconis.jpg|left|thumb|μ Draconis in optical light]]

μ&nbsp;Draconis ([[Social:Latinisation of names|Latinised]] to ''Mu Draconis'') is the star's [[Astronomy:Bayer designation|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 [[Astronomy:Star system|multiple star system]]s, and adopted by the [[Organization:International Astronomical Union|International Astronomical Union]] (IAU).<ref name="planetnaming">{{cite arXiv |title=On the naming convention used for multiple star systems and extrasolar planets |date=2010 |eprint=1012.0707 |class=astro-ph.SR |last1= Hessman |first1=F. V. |last2= Dhillon |first2=V. S. |last3= Winget |first3=D. E. |last4= Schreiber |first4=M. R. |last5= Horne |first5=K. |last6= Marsh |first6=T. R. |last7= Guenther |first7=E. |last8= Schwope |first8=A. |last9= Heber |first9=U. }}</ref>

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").<ref name="k&s">{{cite book
  |author= Kunitzsch, P. |author2=Smart, T. |date = 2006
  |title = A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations
  |edition = 2nd rev.
  |publisher = Sky Pub
  |location = Cambridge, {{wipe|Massachusetts}}
  |isbn = 978-1-931559-44-7

In 2016, the [[Organization:International Astronomical Union|International Astronomical Union]] organized a [[Astronomy:IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref>{{Cite web|url=https://www.iau.org/science/scientific_bodies/working_groups/280/|title=International Astronomical Union {{!}} IAU|website=www.iau.org|access-date=2017-03-31}}</ref> to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.<ref name="TriRpt18">{{cite web | url=https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf | page=5 | title=WG Triennial Report (2015-2018) - Star Names |access-date=2018-07-14}}</ref> 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.<ref name="IAU-LSN"/>

This star, along with [[Astronomy:Beta Draconis|Beta Draconis]] (Rastaban), [[Astronomy:Gamma Draconis|Gamma Draconis]] (Eltanin), [[Astronomy:Nu Draconis|Nu Draconis]] ('Kuma') and [[Astronomy:Xi Draconis|Xi Draconis]] (Grumium) were ''Al ʽAwāïd'', the [[Astronomy:Mother Camels|Mother Camels]], which were known in Latin as the Quinque Dromedarii.<ref>{{cite book
 | last=Allen
 | first=R. H.
 | date=1963
 | title=Star Names: Their Lore and Meaning
 | url=https://archive.org/details/starnamestheirlo00alle/page/207
 | access-date=2010-12-12
 | edition=Reprint
 | publisher=Dover Publications Inc
 | location=New York, NY
 | isbn=978-0-486-21079-7
 | page=[https://archive.org/details/starnamestheirlo00alle/page/207 207]
 | url-access=registration
 }}</ref>

== Cultural references ==
Science fiction writer Frank Herbert chose Arrakis as the name of the primary planet of [[Astronomy:Canopus|Canopus (α&nbsp;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).<ref name="Palumbo2018">{{cite book|author=Donald E. Palumbo|title=A Dune Companion: Characters, Places and Terms in Frank Herbert's Original Six Novels|url=https://books.google.com/books?id=CE1nDwAAQBAJ&pg=PA75|date=1 August 2018|publisher=McFarland|isbn=978-1-4766-6960-1|pages=75–}}</ref>

== References ==
{{Reflist}}

{{Stars of Draco}}


{{DEFAULTSORT:Mu Draconis}}
[[Category:Binary stars]]
[[Category:Draco (constellation)]]
[[Category:Bayer objects|Draconis, Mu]]
[[Category:Flamsteed objects|Draconis, 21]]
[[Category:F-type main-sequence stars]]
[[Category:Stars with proper names|Alrakis]]
[[Category:Hipparcos objects|083608]]
[[Category:Bright Star Catalogue objects|6369 70]]
[[Category:Durchmusterung objects]]
[[Category:Henry Draper Catalogue objects|154905 6]]
[[Category:Gliese and GJ objects|9584]]

{{Sourceattribution|Mu Draconis}}