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Nu Ursae Majoris
Nu Ursae Majoris (Nu UMa, ν Ursae Majoris, ν UMa) is a double star in the northern circumpolar constellation of Ursa Major. The traditional name of this star is Alula Borealis.〔Piazzi, G., ''The Palermo Catalogue'', Palermo, 1814.〕 At an apparent visual magnitude of +3.490,〔 it is bright enough to be seen with the naked eye. Based upon parallax measurements, the distance to ν Ursae Majoris is about .〔
This is a giant star with a stellar classification of K3 III.〔 It has expanded to about 57 times the radius of the Sun and is radiating 775 times the Sun's luminosity.〔 The effective temperature of the outer envelope is 4,070 K;〔 cool enough to give it an orange hue typical of a K-type star.〔 It has a 10th-magnitude optical companion at an angular separation of 7.1 arcseconds.
==Name and etymology==
*The traditional name ''Alula'' (shared with ξ UMa) comes from the Arabic phrase "the First Spring".〔(Richard Hinckley Allen :Star Names — Their Lore and Meaning - Ursa Major, the Greater Bear )〕 The term ''Borealis'' meaning "the north side" in Latin.
*In Chinese, (), meaning ''Three Steps'', refers to an asterism consisting of ν Ursae Majoris, ι Ursae Majoris, κ Ursae Majoris, λ Ursae Majoris, μ Ursae Majoris, and ξ Ursae Majoris. Consequently, ν Ursae Majoris itself is known as (, (英語:the Fifth Star of Three Steps)) and (, (英語:Star of First Lower Step)).〔 ((Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 21 日 )〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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