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Hickson Compact Group 90

The three galaxies—NGC 7173 (left), NGC 7174 (middle ), and NGC 7176 (right)—are part of Hickson Compact Group 90, named after astronomer Paul Hickson, who first cataloged these small clusters of galaxies in the 1980s. NGC 7173 and NGC 7176 appear to be smooth, normal elliptical galaxies without much gas and dust.

The smaller galaxy has been caught in a tug-of-war between a Sumo-wrestler pair of elliptical galaxies. The hapless, mangled galaxy NGC 7174 may have once looked more like our Milky Way, a pinwheel-shaped galaxy. But now that it's caught in a cosmic Cuisinart, its dust lanes are being stretched and warped by the tug of gravity. Unlike the elliptical galaxies, the spiral is rich in dust and gas for the formation of new stars. It is the fate of the spiral galaxy to be pulled like taffy and then swallowed by the pair of elliptical galaxies. This will trigger a firestorm of new stellar creation. If there are astronomers on any planets in this galaxy group, they will have a ringside seat to seeing a flurry of starbirth unfolding over many millions of years to come. Eventually the ellipticals should merge too, creating one single super-galaxy many times larger than our Milky Way. This trio is part of a tight cluster of 16 galaxies, many of them being dwarf galaxies.

Hickson Compact Group 90 lies about 100 million light-years away in the direction of the constellation Piscis Austrinus, the Southern Fish.

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