Globular Clusters and Satellite Galaxies: Companions to the Milky Way

Mercury Spring 2009 Table of Contents

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Image courtesy of Robert Gendler.

by Duncan A. Forbes, Pavel Kroupa, Manuel Metz, and Lee Spitler

Our Milky Way galaxy is host to a number of companions. These companions are gravitationally bound to the Milky Way and are stellar systems in their own right. They include a population of about 150 globular clusters (GCs) and some 30 dwarf satellite galaxies (DSGs).

Globular clusters -- dense, spherical collections from about 10,000 to as many as one million stars -- are well known to amateur astronomers. Satellite galaxies include the Large and Small Magellanic Clouds, visible to the naked eye in the Southern Hemisphere, and a host of smaller, fainter galaxies. These DSGs are more extended and diffuse compared to GCs. In fact the larger satellites of the Milky Way (and other galaxies, for that matter) host their own small systems of GCs.

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