The Tumultuous Milky Way and Its Satellite Galaxies

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Current theories favor the idea that large galaxies such as the Milky Way grow by swallowing neighboring dwarf galaxies. During this process, the dwarf galaxies become severely distorted, producing streams of stars and gas. The Magellanic Stream of gas and the stellar stream associated with the Sagittarius dwarf galaxy consist of debris torn from satellites have been interacting with other dwarfs or with the Milky Way in our local group of galaxies.

Using state-of-the-art simulations, Elena D’Onghia of the Harvard-Smithsonian Center for Astrophysics demonstrates how spiral galaxies and their dwarf satellites form: how dwarf galaxies distort larger spiral galaxies when they pass in the proximity of galactic disks, yielding the magnificent spiral arms that we commonly observe in many disk galaxies like the Milky Way.

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