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The adjacent false-color National Optical Astronomy Observatory (NOAO) image shows a pair of interacting spiral galaxies called Arp 273. These galaxies lie in the constellation Andromeda at a distance of about 200 million light years. The larger galaxy at the upper left is strongly tidally distorted. The companion (seen edge-on in the lower right) exhibits a relatively undisturbed spiral disk, but has a luminous, starburst nucleus (one in which there is a burst of new star formation). The nucleus of the large spiral has properties indicating much less activity than the bright nucleus of its companion. Thus, the large galaxy has a modified disk but little evidence of damage to its nucleus, while the small galaxy has an undisturbed disk but a very active nucleus.