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2 Globular Clusters

Globular clusters comprising 104 to 107 stars were formed early in the history of the Milky Way, and are scattered throughout the halo. The age of the clusters is about 13 Gyr, with an age spread of less than 5 Gyr [23]. According to a frequently updated catalog of globular cluster properties maintained on the web by Harris [68Jump To The Next Citation Point], the globular cluster system numbers roughly 150 clusters. Although the list is fairly complete, two new globular clusters were recently discovered at very low galactic latitudes [81], and there is the prospect for a few more clusters to be hidden behind the bulge or out in the far reaches of the galaxy. The distribution of globular clusters in galacto-centric coordinates is shown in Figure  1View Image.
View Image

Figure 1: Globular cluster distribution about the galaxy. Positions are from Harris [68] and are plotted as black circles on top of the COBE FIRAS 2.2 micron map of the Galaxy using a Mollweide projection. Figure taken from Brian Chaboyer’s website [24].

 2.1 Globular cluster stars
 2.2 Globular cluster structure
 2.3 Globular cluster evolution


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