IAU Symposium 256
The Magellanic System: Stars, Gas, and Galaxies
28 July - 1 August 2008            Keele University (UK)

Outreach: Irregular Dwarf Galaxies
Dwarf galaxies only contain several billion stars. Although several billion stars seems like quite a lot, large galaxies such as the Milky Way has two to four hundred billion stars. Most dwarf galaxies orbit other, larger galaxies. The Large and Small Magellanic Clouds orbit the Milky Way. The Large Magellanic Cloud is not always considered to be a dwarf galaxy, as it has 30 billion stars.

Irregular galaxies simply don't fit either of the other two main shapes for galaxies: elliptical or spiral. Most irregular galaxies were originally elliptical or spiral galaxies which have been distorted by the gravity of larger neighbouring galaxies, as the Large and Small Magellanic Clouds were.
An example of an elliptical galaxy An example of a spiral galaxy A typical irregular galaxy
An elliptical galaxy
A spiral galaxy
An irregular galaxy

Irregular dwarf galaxies usually contain small amounts of metal and large amounts of gas compared to other galaxies, as astronomers believe the earliest galaxies had. This means that they are important for studying the history of the Universe.

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