Our Milky Way is known for being a ruthless devourer, with a history of scarfing down smaller galaxies, which helps it maintain its gorgeous spiral shape. However, a few billion years in the future, our galaxy could be consumed by an equally starving neighbor called Andromeda.
Andromeda, the next large galaxy to ours, is on a hot run to fuse with the Milky Way approximately 4.5 billion years from now. How the gigantic collision will alter the form of the participating galaxies is unclear, but considering Andromeda’s size, scientists know the galaxy is no idler when it comes to rivalry.
According to new research, which was published in the journal Nature on October 2nd, Andromeda may have a way more bloody history than astronomers previously believed.
Utilizing data from five separate telescopes, the research authors discovered the extended halo of the stars at the border of Andromeda’s orbit and identified a minimum of two clusters of stars with definite trajectories and velocities that didn’t appear to correspond to each other, or the rest of the galaxy.
Based on the measured ages of the clusters, the scientists settled they were the residues of two ancient dwarf galaxies that Andromeda had eaten long ago. These discoveries, based on just a limited fraction of Andromeda’s element stars, might likely symbolize a small part of the cosmic remnants of other mergers across the galaxy’s 10-billion-year life length
Lead study author Dougal Mackey, an astronomer at Australian National University, and his colleagues concentrated their analysis on 92 clusters of stars that had been discovered in earlier Andromeda observations. Each of these clusters was hosted in the galaxy’s halo, at a distance of over 81,000 light-years from the galactic nucleus, where the regular movements of ripped remnants would be easier to identify.
The research team calculated the velocities and evident orbits of 77 of these clusters, discovering two separate groups: one older cluster, spinning perpendicular to the galaxy’s disk, and one younger cluster swirling at approximately 90-degree angle to the old ones.
The team defined these groups as the remnants of two ancient merger phenomena that happened billions of years apart.