The Local Supercluster

The Local Group is found on the outskirts of a larger structure dubbed the Local Supercluster which itself is flattened and is roughly centered on the Virgo Cluster.

The locations of the galaxies within the volume of the Local Supercluster are displayed here on an Aitoff equal area grid in celestial coordinates, Right Ascension (R.A.) and Declination (Decl.).

  • All of these objects have measured recessional velocities less than 3,000 km/s.

  • The map is centered on R.A.= 6 hours, Decl. = 0 degrees.

  • The continous lines that rise diagonally through the center of the map show the locus in celestial coordinates of the lines of constant galactic latitude at -20deg, 0 and +20 deg. delineating the Zone of Avoidance, where distant galaxies are obscured at optical wavelengths by the dust and gas within the Milky Way.

  • It is pretty clear on this representation that there are more galaxies on the left side of the map than on the right side. This asymmetry occurs because the Local Group is located on the edge of the Local Supercluster. When we look towards the center, we see lots of galaxies; when we look away from the center, we see many fewer.

  • With a bit more imagination, trace a continuous line through the concentration in Virgo, across the zone of avoidance, through the right side and back again through the north pole. This continuous distribution is the Supergalactic plane. Although less well defined that the galactic plane, its presence indicates that the Local Supercluster, like the Milky Way, is a flattened structure.

    Within the Local Supercluster, galaxies tend to be found in groups and clouds, with other regions being relatively empty.

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