共照耀星云与星系群NGC 7771

共照耀星云与星系群NGC 7771

IFN and the NGC 7771 Group
Image Credit & Copyright: Steve Mandel and Bob Fera

Explanation: Galaxies of the NGC 7771 Group are featured in this intriguing skyscape. Some 200 million light-years distant toward the constellation Pegasus, NGC 7771 is the large, edge-on spiral near center, about 75,000 light-years across, with two smaller galaxies below it. Large spiral NGC 7769 is seen face-on to the right. Galaxies of the NGC 7771 group are interacting, making repeated close passages that will ultimately result in galaxy-galaxy mergers on a cosmic timescale. The interactions can be traced by distortions in the shape of the galaxies themselves and faint streams of stars created by their mutual gravitational tides. But a clear view of this galaxy group is difficult to come by as the deep image also reveals extensive clouds of foreground dust sweeping across the field of view. The dim, dusty galactic cirrus clouds are known as Integrated Flux Nebulae. The faint IFN reflect starlight from our own Milky Way Galaxy and lie only a few hundred light-years above the galactic plane.

Tomorrow’s picture: moon dressing

共照耀星云与星系群NGC 7771
影像提供与版权: Steve Mandel and Bob Fera

说明: 这片很有趣星野的主题是星系群NGC 7771。离我们约有2亿光年远，位于飞马座方向的星系NGC 7771，是影像中央附近的那个侧向大星系。它的大小约为75,000光年，其下方还可见到2个较小的星系，而右方的正向星系则是大螺旋星系NGC 7769。星系群NGC 7771的成员透过重力进行互扰，并重覆发生近距离接近，预期在经过相当长久的宇宙年代后，最后它们会发生星系合并。它们之间的交互作用，可见诸于星系扭曲的外观，以及重力潮汐所产生的众多暗淡恒星流。不过受到分布在视野前景的这大片尘埃的遮掩，很难取得这个星系群的清晰深空影像。这些不停反射银河系星光、名为共照耀星云（IFN）的暗淡尘埃云气，分布在银河星系盘上方约数百光年之处。

明日的图片: moon dressing