Galaxy Mergers

This image illustrates a press release from the January 1994 meeting of the American Astronomical Society. The upper nine images show nearby examples of merging galaxies in an approximate time order, in data from telescopes at Lowell, Kitt Peak, and the Eurpoean Southern Observatory (upper left to lower right: NGC 3690, NGC 520, NGC 6240, Arp 220, NGC 2623, IC 883, NGC 4194, NGC 7252, and NGC 7727). The lower panel shows faint galaxy pairs from HST images in the Hercules.2 survey field. The comparison between nearby and distant samples (at cosmologically interesting look-back times) indicates that the galaxy merger rate has declined dramatically with cosmic time, pointing to an important role for merging in galaxy evolution.

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