Galaxies

Big dwarfs have little dwarfs

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Science  16 Nov 2018:
Vol. 362, Issue 6416, pp. 789
DOI: 10.1126/science.362.6416.789-a

An infrared image of the Large Magellanic Cloud

CREDIT: ESA/NASA/JPL-CALTECH/STSCI

Galaxies grow hierarchically: Small galaxies merge into bigger ones. Large galaxies like our Milky Way are surrounded by dozens of satellite dwarf galaxies, which are still in the process of merging. Those satellite galaxies should themselves be accompanied by even smaller dwarfs, but there is little observational evidence for this. Kallivayalil et al. examined 32 recently discovered dwarf galaxies by comparing astrometric data from the Gaia mission to simulations. They show that at least four of the dwarfs are associated with the Large Magellanic Cloud, the largest satellite galaxy of the Milky Way. This is consistent with standard cosmology.

Astrophys. J. 867, 19 (2018).

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