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Delta Arietis (δ Ari, δ Arietis) is the Bayer designation for a star in the northern constellation of Aries. It has the traditional name Botein which is derived from the Arabic word for "belly". The apparent visual magnitude of this star is 4.35,〔 which is bright enough to be viewed with the naked eye. It has an annual parallax shift of 19.22 mas;〔 corresponding to a physical distance of approximately from Earth. This is an evolved giant star with a stellar classification of K2 III.〔 It belongs to a population known as red clump giants, which means it is generating energy through the fusion of helium at its core.〔 With close to twice the mass of the Sun,〔 the outer envelope has expanded until it is around ten〔 times the Sun's radius. It shines with 45〔 times the Sun's luminosity at an effective temperature of 4,810 K,〔 giving it the orange-hued glow of a K-type star.〔 It is a suspected variable star that ranges in magnitude from 4.33 to 4.37.〔 ==Etymology== The term ''Botein'' is derived from Al Bīrūnī's Al Buṭayn (ألبطين), the dual of ''Al Baṭn'', the Belly. This is the name of star association consisting this star, along with ε Ari, ζ Ari, π Ari, and ρ3 Ari〔 According to the catalogue of stars in the ''Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars'', ''Al Buṭain'' were the title for five stars :δ Ari as ''Botein'', π Ari as ''Al Buṭain I'', ρ3 Ari as ''Al Buṭain II'', ε Ari as ''Al Buṭain III'' dan ζ Ari as ''Al Buṭain IV''〔(Jack W. Rhoads - ''Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars'', Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971 )〕 In the catalogue of stars in the ''Calendarium of Al Achsasi Al Mouakket'', this star was designated Nir al Botain, which was translated into Latin as Lucida Ventris, meaning ''the brightest of the belly''. In Chinese, (), meaning ''Yin Force'', refers to an asterism consisting of δ Arietis, 63 Arietis, ζ Arietis, τ Arietis and 65 Arietis.〔 ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.〕 Consequently, δ Arietis itself is known as (, (英語:the Fourth Star of Yin Force).)〔 (香港太空館 - 研究資源 - 亮星中英對照表 ), Hong Kong Space Museum. Accessed on line November 23, 2010.〕 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 Arietis」の詳細全文を読む スポンサード リンク
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