About 250 million light-years away in a neighborhood of our universe that astronomers had considered quiet and unremarkable, scientists have uncovered an enormous, bizarre galaxy possibly formed from the parts of other galaxies. In optical light (left), UGC 1382 appears to be a simple elliptical galaxy, but spiral arms appeared when astronomers incorporated ultraviolet and deep optical data (middle). Combining that with a view of low-density hydrogen gas (shown in green at right), revealeded that UGC 1382 is gigantic.
It turns out that UGC 1382, a galaxy that had originally been thought to be old, small and typical is 10 times bigger than previously thought and, unlike most galaxies, its insides are younger than its outsides, almost as if it had been built using spare parts. It’s a rotating disk of low-density gas where stars don’t form quickly because the gas is so spread out. UGC 1382 is about 718,000 light-years across, more than seven times wider than the Milky Way, making it one of the three largest isolated disk galaxies ever discovered.
Image Credit: NASA / SDSS / NRAO