Glossary term: 北極星
Description: 北極星是距離北天極最近的亮星(1度以內)。它的正式名稱是小熊座α星,通常被稱為北極星,在中國也叫勾陳一、北辰、宸極。北天球的所有恆星都似乎圍繞著它旋轉,因此它是進行導航和天體測量的絕佳固定點。它的地平高度可以提供觀測地點的大致緯度。不過,由於地球自轉軸的進動,北極星在天球上的位置正在慢慢發生變化,因此再過幾個世紀,北極星就不再能指示北天極的位置了。
北極星是一個由三合星系統。主星是一顆黃超巨星,被命名為北極星Aa;伴星是一顆較小的主序星,被命名為北極星Ab。它們在非常近的軌道上相互繞轉運行。這對恆星還有一顆較大的伴星——北極星B,它是一顆主序星,在2400個天文單位的距離上運行,軌道週期約為29.3年。北極星B可以用普通望遠鏡分辨出來。哈勃太空望遠鏡能夠分辨出北極星三合星系統的所有三個成員。北極星的視星等會有波動,這是因為北極星Aa是一個仙王座變星。北極星系統距離地球約447光年。
Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
This is an automated transliteration of the simplified Chinese translation of this term
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