M31:仙女星系
(原标题: M31: The Andromeda Galaxy)
2023-03-22
浏览次数: 22
你能看多远?肉眼可以轻易看到的最遥远的天体是M31,即巨大的仙女座星系,距离我们超过200万光年。如果没有望远镜,即使是这个巨大的螺旋星系也只是仙女座中一团不起眼、暗淡的星云。但是明亮的白色核心,黑暗的缠绕的尘埃带,明亮的蓝色旋臂和明亮的红色发射星云被记录在我们最近的主要星系邻居的这张令人惊叹的15小时望远镜数字马赛克中。但是我们怎么知道这个螺旋状星云真的离我们这么远呢?这个问题是1920年著名的沙普利-柯蒂斯辩论的核心问题。M31的遥远距离是在20世纪20年代通过对单个恒星的观测确定的,这些恒星改变了它们的亮度,从而放弃了它们的真实距离。结果证明仙女座星系就像我们的银河系一样——这一结论使得宇宙的其余部分比以前想象的要大得多。
查看原文解释
How far can you see? The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy, over two million light-years away. Without a telescope, even this immense spiral galaxy appears as an unremarkable, faint, nebulous cloud in the constellation Andromeda. But a bright white nucleus, dark winding dust lanes, luminous blue spiral arms, and bright red emission nebulas are recorded in this stunning fifteen-hour telescopic digital mosaic of our closest major galactic neighbor. But how do we know this spiral nebula is really so far away? This question was central to the famous Shapley-Curtis debate of 1920. M31's great distance was determined in the 1920s by observations that resolved individual stars that changed their brightness in a way that gave up their true distance. The result proved that Andromeda is just like our Milky Way Galaxy -- a conclusion making the rest of the universe much more vast than had ever been previously imagined.
© Abdullah Al-Harbi