Astronomers have long predicted that our galaxy, the Milky Way, will collide with its nearest large neighbour, Andromeda, in about 5 billion years. However, a new study published in Nature Astronomy suggests that this collision may not be as certain as previously thought.
The researchers behind the study, led by Till Sawala from the University of Helsinki, re-examined existing measurements and included the gravitational influence of other nearby galaxies. Their findings indicate that there is only about a 50% chance that the Milky Way and Andromeda will merge in the next 10 billion years.
The uncertainty arose from previous studies’ assumption that Andromeda’s transverse motion was small, making a head-on collision seem almost certain. However, the new study took into account the uncertainties in existing measurements and simulated thousands of possible trajectories for both galaxies. The researchers also included the gravitational influence of two additional nearby galaxies: M33 and the Large Magellanic Cloud.
According to the study’s results, in about half of the simulated scenarios, the Milky Way and Andromeda do not merge at all within the next 10 billion years. The outcome depends on various factors, including the transverse velocity of Andromeda, which is still uncertain.
The researchers note that even if a merger does happen, it will likely be a gentle outcome, with the galaxies coalescing into a single, larger elliptical galaxy rather than experiencing catastrophic collisions. If the galaxies do not merge, they may settle into a long, slow orbit around each other.
While the study’s findings reduce the certainty of the collision prediction, they also highlight the importance of continued research and exploration of the universe’s mysteries. The researchers acknowledge that future measurements will be necessary to refine our understanding of Andromeda’s transverse velocity and bring us closer to a clearer answer about the Milky Way’s distant future.
Source: https://theconversation.com/astronomers-thought-the-milky-way-was-doomed-to-crash-into-andromeda-now-theyre-not-so-sure-257825