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Theta Leonis (θ Leo, θ Leonis) is a star in the constellation Leo. It has the traditional names Chertan, Chort and Coxa.〔 With an apparent visual magnitude of +3.324〔 it is visible to the naked eye and forms one of the brighter stars in the constellation. The distance from Earth can be directly determined from parallax measurements, yielding a value of about .〔 This is a large star with 2.5 times the mass of the Sun.〔 The spectrum matches a stellar classification of A2 V,〔 making this a seemingly typical A-type main sequence star. However, the spectrum shows enhanced absorption lines of metals, marking this as a chemically peculiar Am star.〔 The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, appears around 12% higher than in the Sun.〔 It is radiating 141〔 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 9,350 K,〔 literally giving it a white-hot glow.〔 Theta Leonis is much younger than the Sun, with an estimated age of around 550 million years.〔 It has a moderately high rate of rotation, with a projected rotational velocity of .〔 Measurements in the infrared band show an excess of emission from the star and its surroundings, suggesting the presence of a circumstellar disk of dust. The temperature of this emission indicates the disk has an orbital radius of 36 AU.〔 ==Etymology== This star has the following traditional names: *Chertan (from Arabic ' = "two small ribs", originally referring to δ and θ Leonis) *Chort (from Arabic ' or ' = "small rib") * (Latin for "hip") In Chinese, (), meaning ''Right Wall of Supreme Palace Enclosure'', refers to an asterism consisting of θ Leonis, β Virginis, σ Leonis, ι Leonis and δ Leonis.〔 ''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, θ Leonis itself is known as (, (英語:the Fourth Star of Right Wall of Supreme Palace Enclosure).),〔 (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.〕 representing (), meaning ''The Second Western Minister''.〔 (English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name ), Hong Kong Space Museum. Accessed on line November 23, 2010.〕 西次相 (Xīcìxiāng), spelled Tsze Seang by R.H. Allen, means "the Second Minister of State" 〔()〕 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「Theta Leonis」の詳細全文を読む スポンサード リンク
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