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Gamma Sagittarii (Gamma Sgr, γ Sagittarii, γ Sgr) is a 3rd-magnitude star in the zodiac constellation Sagittarius. The location of this star forms the tip of the arrow in the bow of Sagittarius the Centaur. It has the proper names Alnasl (''Nasl'', ''El Nasl''), Nushaba (''Nash'') and Warida.〔 This star is close enough to the Earth that its distance can be determined using parallax, yielding a value of about . It has an apparent visual magnitude of +2.98,〔 making it the seventh brightest star in the constellation. A stellar classification of K1 III reveals that this is a giant star,〔 having expanded to an estimated 12 times the Sun's radius.〔 This means it has exhausted the hydrogen in its core and evolved away from the main sequence. The abundance of elements other than hydrogen and helium in this star, what astronomers term the star's metallicity,〔 is lower than in the Sun. Gamma Sagittarii has an effective temperature of 4,760 K,〔 compared to 5,778 K for the Sun.〔 It is this lower temperature that gives Gamma Sagittarii the orange hue that is a characteristic of K-type stars. There is a fainter optical companion located about 50 arcminutes north of this star. It is magnitude 4.7 Cepheid variable star designated W Sagittarii.〔〔 ==Name and etymology== *Alnasl is derived from the Arabic النصل ''al-naşl'' meaning "arrowhead".,〔 Nushaba is derived from the Arabic ''Zujj al-Nashshaba'' meaning the same as Alnasl.,〔 Warida is derived from النعم الوارد ''Al Naʽām al Wārid'', the Going Ostriches, the asterism consisting this star, δ Sgr, ε Sgr and η Sgr. *This star, together with : * *δ Sgr, ε Sgr, ζ Sgr, λ Sgr, σ Sgr, τ Sgr and φ Sgr, comprising the asterism ''Teapot''.〔 (【引用サイトリンク】 publisher = deepsky.astroinfo.org )〕〔(skywatchers )〕 * *δ Sgr and ε Sgr were Akkadian ''Sin-nun‑tu'', or ''Si-nu-nu‑tum'', the Swallow.〔 *In the catalogue of stars in the ''Calendarium'' of Al Achsasi al Mouakket, this star was designated Aoul al Waridah, which was translated into Latin as Prima τού al Warida, meaning ''first going ostrich''. *In Chinese, (), meaning ''Winnowing Basket'', refers to an asterism consisting of γ Sagittarii, δ Sagittarii, ε Sagittarii and η Sagittarii. Consequently, γ Sagittarii itself is known as (, (英語:the First Star of Winnowing Basket).)〔 (AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日 )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gamma Sagittarii」の詳細全文を読む スポンサード リンク
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