The Milky Way changed orientation
- Collision with the dwarf galaxy
- Change in the orientation of the Milky Way
- The event occurred 10 billion years ago
The disk of the Milky Way was likely not always in its current plane. The collision with the massive dwarf galaxy Gaia—Sausage may have gradually tilted it by more than 90°.
This event occurred about 10 billion years ago and was not an instantaneous 'overturning' of the entire galaxy, but a slow change in the orientation of the disk under the influence of gravitational torque over several hundred million years.
Scientists from the University of Durham in the UK, led by Kirill Batrakov, tested a hypothesis that explained the unusually slow movement of stars in the halo by the change in the spatial position of the Milky Way.
To do this, they used a set of cosmological models called Auriga — magnetohydrodynamic simulations of the formation of galaxies like the Milky Way with the highest level of detail available today.
In the studied models, the slowest rotating stellar halos occurred in galaxies that formed early, experienced head-on or close major mergers, followed by a change in the direction of the angular momentum of the disk.
Source: 3DNews
