Glossary term: 紅巨星
Description: 紅巨星是指表面溫度相對較低，但直徑比太陽等主序星大幾十倍甚至上百倍的恆星。相對較低的溫度使恆星表面呈現紅色，而較大的直徑則使恆星的亮度遠超太陽。紅巨星最初是主序星，即類似太陽的恆星，在其內核中通過核聚變將氫燃燒成氦。當這樣一顆恆星的氫燃料耗盡時，它就會開始燃燒氦並合成更重的元素。這時，恆星會膨脹，其表面會在此過程中冷卻下來，隨著體積的增大，恆星會變得更加明亮。太陽將在數十億年後進入紅巨星階段，屆時地球上的生命很可能無法存活。紅巨星的例子有，位於牧夫座的大角星和位於鯨魚座的米拉星。紅巨星的脈動（即恆星反復變大和變小的振盪）並不穩定，在脈動過程中，亮度會發生變化。米拉星就是一個極端的例子，它的亮度可以變化 1000 倍。在天文學家使用的光譜分類中，紅巨星的光譜型大多屬於M型，也有一些屬於K型。紅巨星和所謂的紅超巨星類似，但質量更低。
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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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