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Pi Aquarii (π Aqr, π Aquarii) is the Bayer designation for a binary star in the equatorial constellation of Aquarius. It shares the traditional name Seat with Delta Aquarii, where it has long been misspelled ''Skat.'' It may be from the Arabic word ''ši'at'' "a wish". This system has an apparent visual magnitude of a mean apparent magnitude of +4.57.〔 Based upon parallax measurements, it is located at a distance of roughly from Earth.〔 This is a binary star system with an orbital period of 84.1 days.〔(STARS )〕〔 The primary component is a B-type main sequence star with a stellar classification of B1 Ve.〔 This is a large star with nearly eleven〔 times the mass and over six times the radius of the Sun.〔 Pi Aquarii shines about 7,300〔 times as brightly as the Sun. This energy is being radiated from its outer atmosphere at an effective temperature of 27,094,〔 giving it the blue-hued glow of a B-type star.〔 It is spinning rapidly with a projected rotational velocity of 215 km/s.〔 Pi Aquarii is notable for having undergone a transition from a Be star (showing hydrogen emission lines) into an ordinary B-type star.〔 It is classified as a Gamma Cassiopeiae type〔 variable star and its brightness varies from magnitude +4.45 to +4.71; a range of 0.28. The dominant variability period, , is nearly the same as the orbital period.〔 Pi Aquarii has a reasonable chance of becoming a supernova some day.〔 ==In culture== In Chinese, (), meaning ''Tomb'', refers to an asterism consisting of π Aquarii, γ Aquarii, ζ Aquarii, η Aquarii.〔 ''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, π Aquarii itself is known as (, (英語:the Fourth Star of Tomb).)〔 (AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 16 日 )〕 In the catalogue of stars in the ''Calendarium'' of Al Achsasi al Mouakket, this star was designated Wasat al Achbiya (وسط الأخبية - ''wasath al ahbiyah''), which was translated into Latin as Media Tabernaculorum, meaning ''the middle of luck of the homes (tents)''.〔 This star, along with γ Aqr (Sadachbia), ζ Aqr (Sadaltager / Achr al Achbiya) and η Aqr (Hydria), were al Aḣbiyah (الأخبية), the Tent.〔〔〔 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「Pi Aquarii」の詳細全文を読む スポンサード リンク
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