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Cosmic shock molded both the inner core and the outer halo of the Milky Way, according to a series of studies conducted by an international group of scientists published in Monthly Notices of the Royal Astronomical Society , The Astrophysical Journal Letter and arXiv.org
Astronomers believe that between 8,000 and 10,000 million years ago an unknown dwarf galaxy has rushed into the Milky Way and is no longer in existence. has not survived the impact, has broken quickly and its remains are still around us.
"The collision broke the dwarf galaxy, which let its stars move in very radial orbits", which are long and narrow like needles, Vasily Belokurov, of the University of Cambridge (United Kingdom ), explains in a statement. of the New York Flatiron Institute
The trajectory of these stars brought them very close to the center of the Milky Way, which, for Belokurov, is a "telltale sign that the dwarf galaxy has entered an orbit really eccentric and his fate was sealed. "
The team used data from the Gaia satellite of the European Space Agency, which maps the contents of our galaxy and records the positions of the stars." The trajectories of the stars after this shock earned him the nickname "Gaia with sausage," says Wyn Evans, of Cambridge University, because in retracing the velocities and trajectories of stars, the shape that remained was that of This food
Our galaxy continued to collide with other galaxies, such as the "insignificant galaxy of the Dwarf Sagittarius", but the "galaxy of sausages" was much more mbadive.
When this dwarf galaxy hit the young Milky Way "its penetrating trajectory caused a lot of chaos. The Milky Way disk probably swelled or even fractured after the impact and should have grown back. "
The astronomers have indicated that the evidence of the remodeling of our galaxy is seen in the trajectory of the stars inherited from this galaxy." Galactic sausage "
Alis Deason, of the British University of Durham, pointed out that the stars of the "sausage galaxy" all turn the same distance "from the center of the Milky Way"
In the form of U, they significantly reduce the density of the halo of the Milky Way stars where the stars change direction.
They also identified at least eight large spherical clusters, called globular clusters, which were also introduced Milky Way through the "galaxy of sausage"
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