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+--- Thread: A protogalaxy in the Milky Way may be our galaxy’s original nucleus (/thread-12913.html)
A protogalaxy in the Milky Way may be our galaxy’s original nucleus - C C - Sep 23, 2022
https://www.sciencenews.org/article/milky-way-galaxy-nucleus-oldest-stars-protogalaxy
INTRO: The Milky Way left its “poor old heart” in and around the constellation Sagittarius, astronomers report. New data from the Gaia spacecraft reveal the full extent of what seems to be the galaxy’s original nucleus — the ancient stellar population that the rest of the Milky Way grew around — which came together more than 12.5 billion years ago.
“People have long speculated that such a vast population [of old stars] should exist in the center of our Milky Way, and Gaia now shows that there they are,” says astronomer Hans-Walter Rix of the Max Planck Institute for Astronomy in Heidelberg, Germany.
The Milky Way’s ancient heart is a round protogalaxy that spans nearly 18,000 light-years and possesses roughly 100 million times the mass of the sun in stars, or about 0.2 percent of the Milky Way’s current stellar mass, Rix and colleagues report in a study posted September 7 at arXiv.org... (MORE - details)