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The giant spiral galaxy UGC 2885 may be the largest known in the local universe. It is 2.5 times wider than our Milky Way and contains 10 times as many stars. A number of foreground stars in our Milky Way can be seen in the image, identified by their diffraction spikes. The brightest appears to sit on top of the galaxy’s disc, though UGC 2885 is really 232 million light-years farther away. The giant galaxy is located in the northern constellation Perseus.
The galaxy has also been nicknamed "Rubin's galaxy", after astronomer Vera Rubin (1928–2016), by Benne Holwerda of the University of Louisville, Kentucky, who observed the galaxy with the Hubble Space Telescope. Researchers are still seeking to understand what led to the galaxy's monstrous size. One clue is that the galaxy is fairly isolated in space and doesn't have any nearby galaxies to crash into and disrupt the shape of its disc. Did the monster galaxy gobble up much smaller satellite galaxies over time? Or did it just slowly accrete gas to make new stars?
Using Hubble's exceptional resolution, Holwerda's team is counting the number of globular star clusters in the galaxy's halo – a vast shell of faint stars surrounding the galaxy. An excess of clusters would yield evidence that they were captured from smaller infalling galaxies over many billions of years.
Image Credit: NASA, ESA, and B. Holwerda (University of Louisville)
Image enhancement: Jean-Baptiste Faure
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