Local Group

  • in 1936, the term Local Group was coined by Edwin Hubble to describe the cluster of nearby galaxies to which the Milky Way galaxy belongs.
  • there are 43 galaxies now identified as belonging to the Local Group, more than half of which have only been discovered during the last 30 years.
  • all of the galaxies in the Local Group interact gravitationally.
  • in addition to the Milky Way, there are two other spiral galaxies in the Local Group, the Andromeda Galaxy (M31) and the smaller M33.
  • our galaxy and M31 together contain over 99 percent of the mass of the Local Group.
  • all of the other member of the Local Group are dwarf galaxies, of which the best known are the Large Magellanic Cloud and the Small Magellanic Cloud.
  • some of the dwarf galaxies are so dim that their brightness is less than that of the night sky, making them difficult to detect.
  • the Milky Way had 13 dwarf galaxies that orbit around it in the small way moons orbit around a planet.
  • the Sagittarius dwarf galaxy is so close that it is in the process of being absorbed into the Milky Way.

Sagittarius Dwarf Irregular Galaxy
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  • the Local Group is also interacting with nearby groups of galaxies – it had stretched the Sculptor Group so much that there is no gap of intergalactic space between them. (see belwo for infographic.)

Local Group – Sculptor
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  • on an even larger scale, the Local Group is slowing falling towards the nearby Virgo Cluster of galaxies.

 

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