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C30

NGC 7331

Proper NameNone
Caldwell NumberC30
NGC/IC NumberNGC 7331
ConstellationPegasus
Right Ascension22h 37m 4s
Declination+34° 24' 57"
Distancec.47,400,000 light years
c.14,500,000 parsecs
MagnitudeApparent: +9.25
Absolute: -21.56
DiameterApparent: 9.3'
Actual: 127,900 light years
Hubble TypeSbc spiral
Optimum VisibilitySeptember

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).

The active galaxy C30 occupies the centre of this image, while the four much more distant galaxies known as the 'fleas' can be seen to its east (or left). This entire collection of galaxies, though not formally forming a galaxy group, are sometimes referred to as the NGC 7331 Group or the 'Deer Lick Group'. Imagery provided by Aladin sky atlas

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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