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Delta Arae (δ Arae, δ Ara) is the Bayer designation for a double star in the southern constellation Ara. It has an apparent visual magnitude of 3.62〔 and is visible to the naked eye. Based upon an annual parallax of 16.48 mas, it is about distant from the Earth.〔 Delta Arae is massive B-type main sequence star with a stellar classification of B8 Vn.〔 The 'n' suffix indicates the absorption lines are spread out broadly because the star is spinning rapidly. It has a projected rotational velocity of 255 km/s, resulting in an equatorial bulge with a radius 13% larger than the polar radius.〔 It has a magnitude 9.5 companion G-type main sequence star that may form a binary star system with Delta Arae.〔 There is a 12th magnitude optical companion located 47.4 arcseconds away along a position angle of 313°.〔 ==Etymology== Delta Arae was known as (meaning: "the 3rd (star) of '") in traditional Chinese astronomy.〔Chevalier, S., and Tsuchihashi, P., (1911): "Catalogue d'Étoiles fixes, observés a Pekin sous l'Empereur Kien Long (Qianlong (Chien-Lung)), XVIIIe siecle", ''Annales de l'Observatoire Astronomique de Zô-Sé''.〕〔 (Yi Shi Tong) (1981): .〕 Allen erroneously called it with ζ Arae as ''Tseen Yin'' ().〔 He probably confused constellation "Ara" with "Ari". ''Tseen Yin'' was lain in Aries.〔〔 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「Delta Arae」の詳細全文を読む スポンサード リンク
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