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NGC 7331

A spiral galaxy in the constellation of Pegasus, C30 (or NGC 7331) has similar dimensions to the Milky Way Galaxy, but some structural differences. While the Milky Way is thought to be a barred spiral, C30 shows no evidence of a bar structure, with its spiral arms extending directly from its nucleus. The nuclear bulge is unusual in that it is apparently rotating in the opposite direction to the galaxy's arms (whereas in most galaxies all the components rotate in the same direction).

C30 shares its alignment with a group of four other galaxies, and together these form the NGC 7331 Group, known informally as the Deer Lick Group. This is not a true galactic grouping, as the other four galaxies are approximately ten times as far away as C30, and appear much smaller as seen from Earth (the four more distant galaxies are occasionally known as the 'fleas' for this reason). A little to the south of C30 lies NGC 7320, which does appear to be a companion galaxy to C30, though visually it forms part of another nearby accumulation of galaxies known as Stephan's Quintet.


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