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Gamma Lyrae (γ Lyr, γ Lyrae) is the second brightest star in the northern constellation of Lyra. It has the traditional names Sulafat (Sulaphat), from the Arabic ''al-sulḥafāt'' "turtle", and Jugum,〔 from the Latin "yoke". The connection with turtles is that fine harps were traditionally made of tortoiseshell. The apparent visual magnitude of Sulafat is 3.3,〔 which is readily visible to the naked eye. Parallax measurements yield an estimated distance of from the Earth. This is a giant star with a stellar classification of B9 III,〔 indicating it has exhausted the supply of hydrogen at its core and evolved away from the main sequence. The effective temperature of the outer envelope of this star is 10,080 K,〔 giving it the blue-white hue typical of a B-type star.〔 The interferometry-measured angular diameter of this star is ,〔 which, at its estimated distance, equates to a physical radius of roughly 15 times the radius of the Sun.〔 In 1909, Canadian astronomer Samuel A. Mitchell identified this star as a spectroscopic binary, although he was unable to split the absorption lines of the components. He found that a period of 25.6 days matched his measurements.〔 It was reported as a spectroscopic binary as recently as 2001,〔 but is now believed to be a single star〔〔 with a high rate of rotation for stars of this type.〔 In China, (), meaning ''Clepsydra Terrace'', refers to an asterism consisting of this star, δ2 Lyrae, β Lyrae and ι Lyrae.〔 (AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日 )〕 Consequently, γ Lyrae itself is known as (, (英語:the Third Star of Clepsydra Terrace).) ==References== } \\ & \approx 30\cdot R_ \end〕 }} 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 Lyrae」の詳細全文を読む スポンサード リンク
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