The merging galaxy pair Arp-Madore 417-391 generated a huge cosmic ring
An image captured by the Hubble Space Telescope’s ACS instrument shows Arp-Madore 417-391, or simply AM 417-391, a pair of merging galaxies. It’s part of the Arp-Madore catalog, which collects particularly peculiar galaxies in the southern sky. It includes pairs of galaxies interacting at levels that go up to a merger just like AM 417-391.
The Advanced Camera for Surveys (ACS) instrument is optimized for hunting galaxies and galaxy clusters in the ancient universe. The AM 417-391 pair is “only” 670 million light-years away and makes an excellent object of study for astronomers interested in galaxy mergers.




