《两个星云的故事
(原标题: A Tale of Two Nebulae)
2025-08-22
浏览次数: 1459
这张对天琴座北部音乐星座的彩色望远镜照片显示了M57暗淡的外部光环和更明亮的中央环状区域，俗称环状星云。对现代天文学家来说，M57是一个著名的行星状星云。M57的中心环直径约为一光年，但它绝对不是一颗行星，而是银河系中一颗垂死的类太阳恒星的气体覆盖物。与M57的视大小大致相同，左边较暗且更容易被忽视的棒旋星系是IC 1296。事实上，在100多年前，IC 1296就被认为是一个螺旋星云。这两颗恒星偶然出现在同一个视野中，虽然它们看起来大小相似，但实际上相距很远。距离我们仅2000光年的M57正好在我们的银河系内。银河系外的IC 1296（又名PGC62532）距离我们大约2亿光年。这大约是M57的10万倍远，但由于它们的大小大致相似，前螺旋星云IC 1296也一定比行星状星云M57大10万倍左右。仔细观察21世纪清晰的天体图像，你会发现更多遥远的背景星系散布在画面中。
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This colorful telescopic view towards the musical northern constellation Lyra reveals the faint outer halos and brighter central ring-shaped region of M57, popularly known as the Ring Nebula. To modern astronomers M57 is a well-known planetary nebula. With a central ring about one light-year across, M57 is definitely not a planet though, but the gaseous shroud of one of the Milky Way's dying sun-like stars. Roughly the same apparent size as M57, the fainter and more often overlooked barred spiral galaxy at the left is IC 1296. In fact, over 100 years ago IC 1296 would have been known as a spiral nebula. By chance the pair are in the same field of view, and while they appear to have similar sizes they are actually very far apart. At a distance of a mere 2,000 light-years M57 is well within our own Milky Way galaxy. Extragalactic IC 1296 (aka PGC62532) is more like 200,000,000 light-years distant. That's about 100,000 times farther away than M57 but since they appear roughly similar in size, former spiral nebula IC 1296 must also be about 100,000 times larger than planetary nebula M57. Look closely at the sharp 21st century astroimage to spot even more distant background galaxies scattered through the frame.
© Kent Biggs