Cosmic collision with the galaxy "Sausage" remodeled Milky Way

The stars' paths of galactic fusion have earned them the nickname "Gaia Sausage," according to Wyn Evans of Cambridge. (Reuters)

Astronomers have discovered an ancient cosmic collision with an object, dubbed the galaxy "Sausage", which reshaped the structure of the Milky Way. The accident was a milestone in the history of the Milky Way and helped shape its interior bulge and its exterior halo, according to a series of studies published in the monthly records of the Royal Astronomical Society and The Astrophysical Journal Letters. Scientists suggest that about 8 billion to 10 billion years ago, an unknown dwarf galaxy shattered in our own Milky Way. The dwarf did not survive the impact: it quickly collapsed and the wreckage is now all around us.

"The collision shredded the dwarf, letting his stars move in very radial orbits" that are long and narrow like needles, said Vasily Belokurov of the University of Cambridge in the United Kingdom. The paths of the stars take them "very close to the center of our galaxy." It is a telltale sign that the dwarf galaxy has entered a truly eccentric orbit and that its fate has been sealed. "

Researchers University of Cambridge in the United Kingdom used data from the Gaia satellite of the European Space Agency. This spacecraft has been mapping the stellar contents of our galaxy, recording the journeys of stars as they travel across the Milky Way. Thanks to Gaia, astronomers now know the positions and trajectories of our celestial neighbors with unprecedented accuracy.

The stars' paths of galactic fusion earned them the nickname "Gaia Sausage," said Wyn Evans of Cambridge. "We have traced the velocities of the stars, and the shape of the sausage just jumped in. As the smaller galaxy separated, its stars were thrown into very radial orbits. that remains of the last major merger of the Milky Way, "said Evans.The Milky Way continues to collide with other galaxies, such as the dwarf galaxy's dwarf Sagittarius.

However, the galaxy's sausages were much more mbadive.Its total mbad of gas, stars and dark matter was more than 10 billion times the mbad of our Sun.When the sausage squeezed into the young Milky Way, its piercing trajectory caused The Milky Way disk was probably puffed or even fractured after the impact and should have been repelled.

Sausage debris was scattered all around the inner parts of the Vo ie Milky, creating the & quot; bulge & quot; in the center of the galaxy. "Stellar Halos." Numerical simulations of galactic mashup can replicate these characteristics, says Denis Erkal of the University of Surrey in the United Kingdom

. In simulations conducted by researchers, stars of the Sausage galaxy enter into stretched orbits. The orbits are further elongated by the growing disc of the Milky Way, which swells and becomes thicker as a result of the collision. The evidence of this galactic remodeling is seen in the paths of stars inherited from the dwarf galaxy, said Alis Deason of the University of Durham in the UK. The sausage stars spin around at the same distance from the center of the galaxy, "Deason said.These U-turns make the density in the Milky Way stellar halo drop dramatically where the stars are turning. particularly pleasing to Deason, who predicted this orbital stack almost five years ago.

The new work explains how the stars fell into such narrow orbits in the first place.The new research also identified at least eight large clusters Spherical stars called globular clusters that have been introduced into the milky way by the galaxy of sausage.Small galaxies do not usually have their own globular clusters, so the galaxy of sausages must have been pretty large to accommodate a collection of clusters.

"Although there have been many dwarf satellites falling on the Milky Way the largest of all", said Sergey Koposov of Carnegie Mellon University in the United States, who has studied in detail the kinematics of sausage stars and globular clusters.