Milky Way's Deformation: Collision with Dwarf Galaxy

 Based on data gathered by the European Space Agency's (ESA) Gaia satellite, a study suggests that the disk of the Milky Way, comprising hundreds of billions of stars, is undergoing deformation due to a slow collision with a smaller neighboring galaxy. The study was conducted by a team of physicists at Turin's National Institute of Astrophysics, who examined the movement of 12 million giant stars in our galaxy using Gaia's data.

According to a paper in Nature Astronomy, the study suggests that our galaxy's edge can only deform due to a recent or ongoing collision with a satellite galaxy. This latest research aims to refine the possible reasons for the Milky Way's warping, with theories ranging from tidal forces from satellite galaxies causing gravitational disruptions, to technological advancements that have allowed scientists to model our galaxy's outer deformation in greater detail.

In 2019, for example, a team developed a detailed 3-D map of the galactic warp using measurements from 2,300 Cepheid variables, ultra-luminous stars. Lead author Eloisa Poggio, from the Turin Astrophysical Observatory, explained that they compared their models with the data to measure the warp's velocity, estimating that the warp completes a rotation around the Milky Way's center every 600 to 700 million years.

The team theorizes that the colliding galaxy could be Sagittarius, a dwarf galaxy currently orbiting the Milky Way. Evidence suggests that Sagittarius has already passed through the Milky Way's galactic disk and will eventually be absorbed. Further observations and research will be needed to confirm whether the changes in the warp are indeed caused by satellite galaxies. However, the team concludes that these interacting satellite galaxies seem to play a significant role in shaping the Milky Way's outer disk.