Spiral Galaxy NGC 4921 - Unusual Spiral NGC 4921 in the Coma Galaxy Cluster -...

Spiral Galaxy NGC 4921 - Unusual Spiral NGC 4921 in the Coma Galaxy Cluster - Galaxy NGC 4921 photographed by the Hubble Space Telescope (HST). Located in the cluster of Coma galaxies (Abell 1656) is about 320 million light years old, this spiral galaxy presents an unusual structure with poorly marked arms; some young blue stars are visible but the activity of star formation here is much less strong than in other spiral galaxies. In the background, many more distant galaxies appear. This very deep image taken with the NASA/ESA Hubble Space Telescope shows the spiral galaxy NGC 4921 along with a spectacular backdrop of more distant galaxies. It was created from a total of 80 separate pictures through yellow and near - infrared filters. The Coma Galaxy Cluster, in the northern constellation of Coma Berenices, the hair of Queen Berenice, is one of the closest very rich collections of galaxies in the nearby Universe. The cluster, also known as Abell 1656, is about 320 million light - years from Earth and contains more than 1000 members. The brightest galaxies, including NGC 4921 shown here, were discovered back in the late 18th century by William Herschel. The galaxies in rich clusters undergo many interactions and mergers that tend to gradually turn gas - rich spirals into elliptical systems without much active star formation. As a result there are far more ellipticals and fewer spirals in the Coma Cluster than are found in quieter corners of the Universe. NGC 4921 is one of the rare spirals in Coma, and a rather unusual one - - it is an example of an “” anaemic spiral”” where the normal vigorous star formation that creates a spiral galaxy's familiar bright arms is much less intense. As a result there is just a delicate swirl of dust in a ring around the galaxy, accompanied by some bright young blue stars that are clearly separated out by Hubble's sharp vision. Much of the pale spiral structure in the outer