Monday, June 21, 2021 05:00 PM
The Milky Way is a narrow spiral galaxy with a thick band of stars in the center and large axial arms that stretch across the universe.
Scientists believe that a halo of dark matter surrounds the Milky Way, extending far beyond its visible edge, as it does in other galaxies.
The researchers used data from Gaia, a European Space Agency mission that maps the locations of billions of stars, to study the Hercules Stream, a thick group of stars that orbit the Milky Way at the same rate as the galactic bar.
Also, because the stars in the Hercules stream are gravitationally trapped by the axial ribbon, slowing the ribbon’s rotation will cause the stars to creep outward to keep their orbits in sync with the ribbon’s rotation.
The researchers found evidence of such cosmic motion when they investigated the chemical composition of stars, and the stars of the Hercules Stream are rich in heavier elements, indicating that these stars formed near the center of the galaxy, where stars are about 10 times richer in minerals than stars in the outskirts of galaxy.