A Heavy Metal Cosmic Whodunit

(Slate::Bad Astronomy) – Phil Plait:

Our Milky Way galaxy has at least 150 globular clusters orbiting it, and in general they can be divided into two groups: Halo clusters and disk clusters. As you might expect from the names, halo globulars tend to have orbits that are way far removed from the galaxy itself, staying out in its halo. Disk clusters stick closer in to the flat plane of the galaxy.

Compared to the Sun, both kinds of globulars have stars that are deficient in heavy elements (for astronomers, that means any element heavier than hydrogen and helium, which, for historical and mainly traditional reasons nowadays, astronomers confusingly call “metals”). …

bad_astronomy 2016/06/12 globular_cluster

Globular cluster NGC 6496

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