The Milky Way is twisted and deformed by the gravity of a satellite galaxy, rather than static, as previously thought.

Scientists from the University of Edinburgh have discovered that the Milky Way is twisted and deformed under the influence of gravity of the satellite galaxy, the Large Magellanic Cloud. The results of the study were published in the journal Nature Astronomy.

It is noted that for a long time the galaxy in which the solar system is located was considered relatively static. However, about 700 million years ago, its gravitational interaction with the Large Magellanic Cloud galaxy took place.

Study authors Dr Michael Petersen and Professor Jorge Penarrubia, using a sophisticated statistical model that calculated the speed of the Milky Way’s farthest stars, proved that the impact of the collision with this small galaxy, which became a satellite of the Milky Way, is still felt today. 

The Large Magellanic Cloud galaxy is surrounded by an extended halo of dark matter, the elusive particles of which have a serious gravitational effect on the movement of stars and gas in the Universe. 

The researchers found that the enormous gravitational force of the galaxy’s dark matter halo attracts and twists the spiralling disk of the Milky Way toward the constellation Pegasus at a speed of 32 kilometers per second, or 115,200 kilometers per hour. 

As astrophysicists emphasized, now, in order to describe the evolution of our Galaxy, it is necessary to create a new generation of models of the Milky Way. 

The fact that the Milky Way is not moving to the current location of the Large Magellanic Cloud, but to its point on the previous trajectory, was also unexpected. 

“This discovery definitely breaks the spell that our galaxy is in some sort of equilibrium state. Actually, the recent infall of the LMC is causing violent perturbations onto the Milky Way. Understanding these may give us an unparalleled view on the distribution of dark matter in both galaxies”

said Jorge Penarrubia.