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Delta Corvi (δ Crv, δ Corvi) is a star in the southern constellation of Corvus. It has the traditional name Algorab (from Arabic الغراب ''al-ghuraab'', meaning "the crow"). This is a third magnitude star at a distance of from Earth. In 1823, it was found to be a wide double star by British astronomers James South and John Herschel. Since that time, the position of the two stars with respect to each other has not changed.〔 This star has more than 2.7 times the mass of the Sun, which is causing it to radiate a much higher energy output—roughly 69 times the Sun's luminosity. The effective temperature of the outer atmosphere is ,〔 giving it the white hue of an A-type star.〔 The spectrum matches a stellar classification of .〔 However it is more luminous—65-70 times that of the Sun—than it would be if it were on the main sequence. Hence it is either a subgiant star around 260 million years old that has nearly exhausted the supply of hydrogen at its core and is in the process of evolving away from the main sequence of stars like the Sun, or a pre main sequence star around 3.2 million years old that has not completely condensed and settled on the main sequence.〔 A 2006 study found that Algorab displayed no excess infrared emission that would otherwise suggest the presence of circumstellar matter,〔 however warm interstellar dust was detected in a 2014 study.〔 It has a magnitude 9.3 companion, HR 4757 B, with a classification of K2Ve at an angular separation of 24.2 arcseconds along a position angle of 214°.〔〔 Although the two stars share a common proper motion,〔 the significant differences in their estimated ages suggests that they may not be physically connected.〔 In Chinese, (), meaning ''Chariot (asterism)'', refers to an asterism consisting of δ Corvi, γ Corvi, ε Corvi and β Corvi.〔 ''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 Corvi itself is known as (, (英語:the Third Star of Chariot).).〔 (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.〕 USS Algorab (AKA-8) is a United States navy ship. ==References== 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 Corvi」の詳細全文を読む スポンサード リンク
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