Beta Sagittarii

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
• β² Sagittarii

β¹ Sagittarii's two components are designated β¹ Sagittarii A, also named Arkab Prior, 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).

The system's traditional name Arkab derives from the Arabic عرقوب ^carqÅ«b meaning Achilles Tendon. The two constituents bore the traditional names Arkab Prior and Arkab Posterior since β¹ leads β² (or β² follows β¹) across the sky. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) 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. 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 á¹¢uradain (الصردين), the two Surad, "desert birds".

In Chinese, (), 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 (, .) and (, .)

Namesakes

USS Arkab (AK-130) was a United States Navy named after the system.

References