Galaxies of the NGC 7771 group are interacting, making repeated close passages that will ultimately result in galaxy-galaxy mergers on a cosmic timescale.
NGC7771组星系相互作用，反复关闭通道，最终在宇宙时间尺度上形成星系与星系的结合。
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Meanwhile, its place is taken by hotter intergalactic gas from farther out on the edge of the galaxy, which cools as it is compressed and flows into the galaxy.
If many such chains were created in a differentially rotating galaxy, the distribution of stars would resemble the observed distribution in a spiral galaxy.