Dwarf Galaxies

An unusual satellite of the Milky Way

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Science  11 Mar 2016:
Vol. 351, Issue 6278, pp. 1163-1164
DOI: 10.1126/science.351.6278.1163-f

Cosmological simulations indicate that large galaxies such as our Milky Way should be surrounded by numerous “dwarf” galaxies. Only in recent years have large surveys enabled systematic searches for these faint objects. Martin et al. have investigated one recently identified candidate, Triangulum II. They find that it is indeed a dwarf galaxy, but one with odd properties. Its fraction of elements heavier than helium (its metallicity) is among the lowest known, and its stars move about more in the outskirts than in the center of the dwarf galaxy. This implies a dynamically recent interaction with a passing body—perhaps another dwarf galaxy.

Astrophys. J. 10.3847/0004-637X/818/1/40 (2016).

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