Cluster of Galaxies Abell496
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Cluster of Galaxies Abell496

May 19, 2005
Clusters of galaxies are some of the largest cosmic structures that are kept together by the combined gravitational pull of its constituents. They frequently extend over many millions of light-years and are usually again grouped to the hierarchically next-higher level of structure, the so-called superclusters . Superclusters, in turn, often line up in extended filaments, hundreds of millions of light-years long; together, they form the foam- or sponge-like texture of the observable Universe.

PR Photo 46f/99 shows the galaxy cluster Abell 496, as observed with the WFI . It contains many hundreds of individual galaxies. The most prominent is a large and bright galaxy, close to the center. The mass of this galaxy is more than 1012 times that of our Sun.

The recession velocities of the galaxies in Abell 496 have been measured as about 10,000 km/s. According to Hubble's law for the expansion of the Universe, this places the cluster at a distance of about 500 million light-years. At that distance, the field shown in PR Photo 46f/99 measures about 4.5 million light-years on a side.

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