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Gamma Ursae Minoris (γ UMi, γ Ursae Minoris; also 13 UMi) is a star in the northern circumpolar constellation of Ursa Minor. It has the traditional name Pherkad, which derives from the Arabic فرقد ''farqad'' "calf", short for ''aḫfa al farkadayn'' "the dim one of the two calves", Pherkad and Kochab. (The full name Ahfa al Farkadain is now applied to Zeta Ursae Minoris.) Gamma Ursae Minoris is sometimes called ''Pherkad Major'' to distinguish it from 11 Ursae Minoris ''Pherkad Minor.'' Together with Beta Ursae Minoris, or Kochab, Gamma forms the end of the dipper pan of the "Little Dipper", which is a colloquial name for the constellation. Pherkad and Kochab are sometimes called the "Guardians of the Pole" or the "Indestructibles", as they appear to circle around the north star Polaris as the Earth rotates.〔 In Chinese, (), meaning ''North Pole'', refers to an asterism consisting of γ Ursae Minoris, β Ursae Minoris, 5 Ursae Minoris, 4 Ursae Minoris and Σ 1694.〔 ''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, γ Ursae Minoris itself is known as (, (英語:the First Star of North Pole).),〔http://zh.wikipedia.org/wiki/%E5%8C%97%E6%A5%B5_%28%E6%98%9F%E5%AE%98%29〕 representing (), meaning ''Crown Prince''〔 (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.〕 Gamma Ursae Minoris has apparent magnitude +3.05〔 and can be readily observed with the naked eye even in a city-lit night sky. Based upon parallax measurements, it is approximately from Earth,〔 giving it an absolute magnitude of –2.84.〔 Measurement of the star's spectrum resulted in a stellar classification of A3 Iab, with the luminosity class of 'Iab' indicating this is an intermediate luminosity supergiant star. The effective temperature of the star's outer envelope is 8,280 K,〔 giving it the typical white hue of an A-type star.〔 It is rotating rapidly, with the projected rotational velocity of 〔 providing a lower limit on the azimuthal velocity along the star's equator. This is classified as a shell star that has a circumstellar disk of gas around the star's equator, which may be causing it to vary in magnitude.〔 It is 1100 times more luminous than the Sun, and possesses a radius 15 times that of the Sun.〔 ==Pherkad in fiction== Star Pherkad (spelled as ''Pherkard'') also features in Cthulhu Mythos, in the short story "The Thing in the Library", by Crispin Burnham and E.P. Berglund. This star is mentioned as the stellar abode of the flaming Outer God Yomagn'tho.〔 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 Ursae Minoris」の詳細全文を読む スポンサード リンク
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