Virgo cluster

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The nearest large cluster of galaxies, and the centre of the local supercluster. It is an irregular, roughly elliptical cluster of over 2000 galaxies, the brightest of which are within the reach of amateur telescopes. Its distance is approximately 55 million l.y., and its diameter 9 million l.y. The cluster spans 12 ° of sky, spilling northwards over the border of Virgo into Coma Berenices; hence it is sometimes also known as the Coma–Virgo Cluster, but should not be confused with the separate Coma Cluster, which is considerably more distant. The Virgo Cluster has a comparatively high proportion of spirals, many dwarf galaxies, and a mass of 2 to 5 × 1014 solar masses. The four brightest members, all ellipticals, are M49 (NGC 4472), M87 (NGC 4486, a giant elliptical galaxy with an unusual jet emanating from its nucleus), M60 (NGC 4649), and M86 (NGC 4406). There is evidence of a slight asymmetry in redshifts between the spirals and the ellipticals, suggesting that the cluster is in fact two clusters superimposed along the line of sight.

Subjects: Astronomy and Astrophysics.

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