Astronomers Found an Ancient Galaxy With a Halo of Dark Matter
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Astronomers Found an Ancient Galaxy with a Halo of Dark Matter:
Some 163,000 light-years from the Milky Way is a much smaller, much more ancient galaxy: Tucana II, so named for the tropical bird-resembling constellation in which it sits. Sitting at the periphery of our galaxy's gravitational pull, Tucana II provides researchers with the opportunity to understand the composition of the earliest galactic structures in the universe.
Now, a team of astronomers has found evidence of an extended dark matter halo around the galaxy. Their research was published today in the journal Nature Astronomy.
"We know [dark matter] is there because in order for galaxies to remain bound, there must be more matter than what we see visibly, from starlight," said Anirudh Chiti, an astronomer at the Massachusetts Institute of Technology, in a phone call. "That led to the hypothesis of dark matter existing as an ingredient that holds galaxies together; without it, galaxies that we know, or at least of the stuff at their outskirts, would just fly apart."
Journal Reference:
Anirudh Chiti, Anna Frebel, Joshua D. Simon, et al. An extended halo around an ancient dwarf galaxy, Nature Astronomy (DOI: 10.1038/s41550-020-01285-w)
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