The Milky Way was engaged in a frontal collision with a smaller dwarf galaxy, dubbed as “Sausage galaxy,” at the beginning of its history, an incident that reconfigured the architecture of our Galaxy, a recent study found. Based on information gathered by the ESA’s Gaia mission, the scientists had estimated that the impact took place about 8-10 billion years ago when the dwarf galaxy was torn apart during the collision.
The collision left behind stars that float in space in long and narrow orbits across the Milky Way, leading the team behind the research to dub them as “sausage stars.”
“We plotted the speeds of the stars, and the shape of the sausage jumped on us. When the smallest galaxy broke, its stars were launched into very radial orbits. These ‘sausage stars’ are what’s left of the last great fusion of the Milky Way,” said Wyn Evans from the Cambridge University.
Early Milky Way collision with the “Sausage galaxy,” a dwarf galaxy, caused many changes in our galaxy
The “Sausage galaxy” implicated in the impact with the early Milky Way possessed a mass of over ten billion times the volume of the Sun. Also, upon the crash, the Milky Way disk could have ruptured, and since then it might have replenished.
It is assumed that the debris left behind by the collision created the bump at the center of the Milky Way and the stellar halo that encircles it.
The team also pinpointed eight globular clusters that might have been embedded by our galaxy during its collision with the “Sausage galaxy,” a dwarf galaxy, that was torn apart by the galactic crash.
The path of the stars of the “Sausage Galaxy” was “very close to the center of our galaxy. This is a tell-tale sign that the dwarf galaxy came in on a really eccentric orbit and its fate was sealed,” explained Vasily Belokurov from the University of Cambridge.