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Theta Serpentis (θ Ser, θ Serpentis) is a star system in the constellation Serpens. It is approximately 132 light years from Earth. Theta Serpentis also has the traditional name Alya, or Alga, from the Arabic الية ''’alyah'' "fat tail (of a sheep)". In the catalogue of stars in the ''Calendarium'' of Al Achsasi al Mouakket, this star was designated Dzaneb al Haiyet, which was translated into Latin as Cauda Serpentis, meaning ''the serpent's tail''. In Chinese, (), meaning ''Left Wall of Heavenly Market Enclosure'', refers to an asterism which is represent eleven old states in China, consisting of θ Serpentis, δ Herculis, λ Herculis, μ Herculis, ο Herculis, 112 Herculis, ζ Aquilae, η Serpentis, ν Ophiuchi, ξ Serpentis and η Ophiuchi.〔 ''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 Serpentis itself is known as (, (英語:the Seventh Star of Left Wall of Heavenly Market Enclosure)), represent the state Xu (徐).〔 (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.〕〔 (English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name ), Hong Kong Space Museum. Accessed on line November 23, 2010.〕 Both Theta-1 Serpentis and Theta-2 Serpentis are white A-type main sequence dwarfs. θ¹ has an apparent magnitude of +4.62 while the slightly dimmer θ² has a magnitude of +4.98. These two stars are 22 arcseconds apart on the sky, putting them at least 900 astronomical units apart with an orbital period of at least 14,000 years. Both stars are similar to each other in all respects, having luminosities of 18 and 13 times solar respectively, radii of about twice solar and also masses of roughly 2 times that of our Sun. Both star have a surface temperature of 8,000 kelvins. The third star in the system, Theta Serpentis C, is a yellow G-type star with an apparent magnitude of +6.71. It is separated by 7 arcminutes from θ². ==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「Theta Serpentis」の詳細全文を読む スポンサード リンク
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