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Theta Boötis (θ Boo, θ Boötis) is a star in the constellation Boötes. It has the traditional name Asellus Primus (Latin for "first donkey colt")〔(Star Name - R.H.Allen p.105 )〕 and the Flamsteed designation 23 Boötis. This star, along with the other ''Aselli'' (ι Boo and κ Boo) and λ Boo, were Al Aulād al Dhiʼbah (أولاد الضّباع - ''al aulād al dhiʼb''), "the Whelps of the Hyenas".〔 In Chinese, (), meaning ''Celestial Spear'', refers to an asterism consisting of θ Boötis, κ2 Boötis and ι Boötis.〔 ''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 Boötis itself is known as (, (英語:the Third Star of Celestial Spear).)〔 (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.〕 ==Properties== Theta Boötis has apparent magnitude +4.04 and belongs to the spectral class F7V. It is approximately 47 light years from Earth. From about 4300 BC until 3942 BC, it was the closest star to the celestial north pole visible to the naked eye, although it was still too far away and too dim to be regarded as a pole star. There is a nearby 11th magnitude optical companion star about 70 arcseconds away. This is a class M2.5 dwarf that is separated by approximately 1,000 AUs. It is uncertain whether they are gravitationally bound, but they do have a common motion through space and so the two stars probably share a common origin. 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 Boötis」の詳細全文を読む スポンサード リンク
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