Its abbreviation is UMi. It is a northern constellation that contains the North Star. In Greek mythology, it is named after the transformation of the hunter Arcas, born to the god Zeus and Callisto, and depicts Arcas as a bear together with his mother (Ursa Major). Alpha Acanthus is a supergiant star with a magnitude of +2.0 and a spectral type of F7, and is a spectroscopic binary star with a period of 29.6 years. This star is currently only 51 minutes away from the pole of the celestial sphere's diurnal motion, so it is always visible in the north, hence the name Polaris. However, due to the phenomenon of precession, the north celestial pole is gradually moving away from this star. Source: Heibonsha World Encyclopedia, 2nd Edition Information |
略号はUMi。北極星を含む北天の星座。ギリシア神話では大神ゼウスとカリストとの間に生まれた猟師アルカスの変身譚に由来し,母(おおぐま座)とともに熊になった姿を表している。α星は光度+2.0等,スペクトル型F7の超巨星で,周期29.6年の分光連星である。この星は現在天球の日周運動の極から51分しか離れていないので,つねに北の方角に見え,北極星の名がある。しかし歳差現象により天の北極はしだいにこの星から離れていく。
出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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