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继承前人之ZZ每日一图081215

2008/12/15镜像同步4 回复

Abell 2218: A Galaxy Cluster Lens Credit: Andrew Fruchter (STScI) et al., WFPC2, HST, NASA Explanation: Gravity can bend light, allowing huge clusters of galaxies to act as telescopes. Almost all of the bright objects in this Hubble Space Telescope image are galaxies in the cluster known as Abell 2218. The cluster is so massive and so compact that its gravity bends and focuses the light from galaxies that lie behind it. As a result, multiple images of these background galaxies are distorted into long faint arcs -- a simple lensing effect analogous to viewing distant street lamps through a glass of wine. The cluster of galaxies Abell 2218 is itself about three billion light-years away in the northern constellation of the Dragon (Draco). The power of this massive cluster telescope has allowed astronomers to detect a galaxy at redshift 5.58, the most distant galaxy yet measured. This young, still-maturing galaxy is faintly visible to the lower right of the cluster core. Abell 2218: 一个形成引力透镜的星系团说明: 引力可将光线弯曲，使得一个巨大的星系团产生透镜般的效果。在这一张由哈勃太空望远镜所公布的照片中，几乎所有明亮的天体都星系团Abell 2218的成员星系。这个星系团是如此的紧密，而且质量如此巨大，以致于它的引力可以使位于它后面的星系所发出的光线弯曲并聚焦成像，因而星系团后方星系就被变形成长弧状的多重影像。这种透镜效应有点像透过一瓶酒来看远方的街灯。星系团Abell 2218位于天龙座，距离地球30亿光年。由于这个星系团的引力透镜效应，使得天文学家得以测出一个红移量高达5.58的星系，也是目前所测得最遥远的星系。影像中位在星系团核心右下方隐约可见的天体就是这个仍处于婴儿时期的年轻星系。原文：http://antwrp.gsfc.nasa.gov/apod/ap080210.html 译文：http://www.astron.sh.cn/picbase/daily/2008/0805/080527/daily.htm

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