双鱼座的壳状星系

双鱼座的壳状星系

Shell Galaxies in Pisces
Image Credit & Copyright: George Williams

Explanation: This spectacular intergalactic skyscape features Arp 227, a curious system of galaxies from the 1966 Atlas of Peculiar Galaxies. Some 100 million light-years distant within the boundaries of the constellation Pisces, Arp 227 consists of the two galaxies prominent above and left of center, the shell galaxy NGC 474 and its blue, spiral-armed neighbor NGC 470. The readily apparent shells and star streams of NGC 474 are likely tidal features originating from the accretion of another smaller galaxy during close gravitational encounters that began over a billion years ago. The large galaxy on the bottom righthand side of the deep image, NGC 467, appears to be surrounded by faint shells and streams too, evidence of another merging galaxy system. Intriguing background galaxies are scattered around the field that also includes spiky foreground stars. Of course, those stars lie well within our own Milky Way Galaxy. The telescopic field of view spans 25 arc minutes or just under 1/2 degree on the sky.

Tomorrow’s picture: pixels in space

双鱼座的壳状星系
影像提供与版权: George Williams

说明: 这片壮观星系际景观的主角是Arp 227，一个由1966年《奇特星系图集》所收录的特殊星系系统。Arp 227位于双鱼座的边界内，是由2个距离我们约1亿光年远的大星系所组成，它们分别为影像中左上方的壳状星系NGC 474及其邻近的泛蓝螺旋星系NGC 470。NGC 474显而易见的壳层和恒星流，很可能是10多亿年前与另一个较小星系接近时，吸积了这个小星系后所产生的。这幅深空影像右下方的大星系NGC 467，周围看似也环拱着壳层和恒星流，显示它亦是一个星系合并系统。视野里，还可见到散布在各处的吸晴背景星系，以及近在银河系内的前景带芒恒星。这片望远镜视野宽约25角分，等同于涵盖了略小于1/2度的天空。

明日的图片: pixels in space