遥远星系的光芒

The brilliant cascade of stars through the middle of this image is the galaxy ESO 318-13 as seen by the Hubble Space Telescope in this image from 2012. Despite being located millions of light-years from Earth, the stars captured in this image are so bright and clear one could almost attempt to count them.

ESO 318-13 is sandwiched between a vast collection of bright celestial objects. Several stars near and far dazzle in comparison to the neat dusting contained within the galaxy. One that particularly stands out is located near the center of the image, and looks like an extremely bright star located within the galaxy. This is, however, a trick of perspective. The star is located in the Milky Way, our own galaxy, and it shines so brightly because it is so much closer to us than ESO 318-13.

There are also a number of tiny glowing disks scattered throughout the frame that are more distant galaxies. In the top right corner, an elliptical galaxy can be clearly seen, a galaxy which is much larger but more distant than ESO 318-13. Peeking through ESO 318-13, near the right-hand edge of the image, is a distant spiral galaxy.

Galaxies are largely made up of empty space; the stars within them only take up a small volume, and providing a galaxy is not too dusty, it can be largely transparent to light coming from the background. This makes overlapping galaxies like these quite common.

Image Credit: NASA/ESA/Hubble

这张2012年哈勃太空望远镜拍摄的照片中，穿过这张照片中间大量明亮恒星的是ESO 318-13星系。尽管该星系位于距离地球数百万光年的地方，但这张照片中拍摄到的恒星非常明亮清晰，几乎可以数得清它们的数量。

ESO 318-13被夹在大量明亮天体之间。与星系中整齐的尘埃相比，远近的几颗恒星都显得耀眼夺目。有一颗特别突出的恒星位于图像的中心附近，看起来像星系中一颗非常明亮的恒星。然而，这是一种透视技巧。这颗恒星位于银河系，我们自己的星系，它之所以如此明亮，是因为它比ESO 318-13离我们更近。

还有一些微小的发光盘散布在整个框架中，它们是更遥远的星系。在右上角，可以清楚地看到一个椭圆星系，这个星系比ESO 318-13大得多，但也远得多。透过ESO 318-13，靠近图像右侧边缘，是一个遥远的螺旋星系。

星系主要由空旷的空间组成。它们内部的恒星只占很小的体积，如果一个星系没有太多尘埃，它对来自背景的光线基本上是透明的。这使得像这样的重叠星系很常见。

影像来源：NASA/ESA/Hubble