Beta Sagittarii
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Beta Sagittarii (β Sagittarii, abbreviated Beta Sgr, β Sgr) is the common designation shared by two star systems in the constellation of Sagittarius, themselves designated β1 Sagittarii (itself a probable binary star) and β2 Sagittarii. The two systems are separated by 0.36° in the sky.
β1 Sagittarii's two components are designated β1 Sagittarii A, also named Arkab Prior,{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |accessdate=13 October 2016}} and β1 Sagittarii B (sometimes designated Arkab Prior A and B). β2 Sagittarii is named Arkab Posterior. Beta Sagittarii is also referred to by the traditional name Arkab.
Nomenclature
β Sagittarii (Latinised to Beta Sagittariii) is the groups's Bayer designation; β1 and β2 Sagittarii, those of its two constituents. The designations of β1's components – β1 Sagittarii 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).{{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. }}
The system's traditional name Arkab derives from the Arabic عرقوب carqūb meaning Achilles Tendon.[http://www.almaany.com/ar/dict/ar-ar/%D8%B9%D8%B1%D9%82%D9%88%D8%A8/ http://www.almaany.com/ar/dict/ar-ar/%D8%B9%D8%B1%D9%82%D9%88%D8%A8/ – تعريف و معنى عرقوب في معجم المعاني الجامع – معجم عربي عربي تعريف و معنى عرقوب في معجم المعاني الجامع – معجم عربي عربي] The two constituents bore the traditional names Arkab Prior and Arkab Posterior since β1 leads β2 (or β2 follows β1) across the sky.{{citation needed|date=October 2016}} In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN){{citation
| url=https://www.iau.org/science/scientific_bodies/working_groups/280/
| title=IAU Working Group on Star Names (WGSN)
| publisher=International Astronomical Union
| accessdate=22 May 2016 | postscript=. }} to catalogue and standardize proper names for stars. The WGSN states that in the case of multiple stars the name should be understood to be attributed to the brightest component by visual brightness.{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin2.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 2 |accessdate=12 October 2016}} The WGSN approved the names Arkab Prior and Arkab Posterior for β1 Sagittarii A and β2 Sagittarii on 5 October 2016 and they are now so entered in the IAU Catalog of Star Names.
β1 and β2 Sagittarii, together with Alpha Sagittarii, were Al Ṣuradain (الصردين), the two Surad, "desert birds".{{cite book
| last=Allen
| first=R. H.
| year=1963
| authorlink=Richard Hinckley Allen
| title=Star Names: Their Lore and Meaning
| url=https://archive.org/details/starnamestheirlo00alle/page/357
| accessdate=4 September 2012
| edition=Reprint
| publisher=Dover Publications Inc
| location=New York
| isbn=0-486-21079-0
| page=[https://archive.org/details/starnamestheirlo00alle/page/357 357]
| url-access=registration
}}
In Chinese, {{lang|zh|天淵}} ({{lang|zh-Latn|Tiān Yuān}}), meaning Celestial Spring, refers to an asterism consisting of β1 Sagittarii, β2 Sagittarii, and Alpha Sagittarii, Consequently, β1 and β2 Sagittarii themselves are known as {{lang|zh|天淵一}} ({{lang|zh-Latn|Tiān Yuān yī}}, {{langx|en|the First Star of Celestial Spring}}.) and {{lang|zh|天淵二}} ({{lang|zh-Latn|Tiān Yuān èr}}, {{langx|en|the Second Star of Celestial Spring}}.){{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0607/ap060702.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 2 日]
=Namesakes=
USS Arkab (AK-130) was a United States Navy {{sclass|Crater|cargo ship|2}} named after the system.
References
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