The Milky Way contains more than 100 billion stars, but did not come from all honestly. At least a dozen times in the last 12 billion years, the Milky Way collided with a neighboring galaxy and engulfed it, engulfing that neighbor’s stars and blending them into a growing stew of stolen suns.
With each merger of galaxies, the shape, size, and motion of our galaxy changed forever, eventually becoming iconic. spiral we acknowledge today. Now, in a recent study published in the October 2020 issue of the magazine. Monthly notices of the Royal Astronomical Society, researchers have tried to develop this spiral. Using artificial intelligence (AI) to match different clusters of stars in their age, motion, and chemical composition, the team found evidence of five large-scale galactic mergers (each involving 1
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This newly discovered catastrophe with the so-called Kraken Galaxy not only helps fill the mysterious Milky Way family tree, but can also help astronomers figure out what our galaxy looked like in its earliest days, the study’s authors say.
“The collision with the Kraken must have been the most significant fusion the Milky Way has ever experienced,” said study lead author Diederik Kruijssen, an astronomer at the University of Heidelberg in Germany. said in a statement. “The merger with Kraken took place 11 billion years ago, when the Milky Way was four times less massive. [than today]. As a result, the collision really changed what the Milky Way looked like at the time. “
In their new study, Kruijssen and colleagues used computer simulations to analyze all known globular clusters – old, dense spheres with up to 1 million stars, all of which formed at about the same time – in the Milky Way. Our galaxy hosts at least 150 of these clusters, which astronomers believe are “fossils” of the ancient galaxies that the Milky Way has swallowed throughout its long and hungry history.
The researchers trained an AI algorithm to identify globular clusters based on shared star properties, initially running the algorithm on thousands of simulated galaxies. After the algorithm was able to accurately predict the formation, evolution, and destruction of globular clusters in these imaginary galaxies, the team left its AI on the Milky Way.
Using data from the Gaia spacecraft (which gave us the most complete map of the Milky Way), the algorithm analyzes the age, motion, and chemical composition of the known globular clusters in our galaxy to recreate the cosmic fusions that landed them there. The team’s analysis accurately predicts four known mergers in the past of the Milky Way – including the so-called Sausage Gaia a fusion that added several billion stars to the protrusion of our galaxy about 9 billion years ago – as well as the previously unknown Kraken fusion.
And this merger was a beast. According to the team, Kraken may have been the largest and oldest galactic collision in the history of the Milky Way. The merger occurred when the Milky Way was only part of its current size and may have added to our galaxy 13 globular clusters that can still be identified today. While the Gaia sausage fusion eventually added more solar mass to the Milky Way (worth more than 20 spherical clusters) than that of Kraken, our galaxy was significantly larger when the sausage fusion occurred and was probably less susceptible. of major structural changes, the researchers wrote.
This new open fusion is just a small part of the puzzle. As the path to galaxy formation is littered with collisions like these, it is likely that much smaller mergers have also contributed to the Milky Way we know today. Astronomers suspect that at least 15 other mergers may be lurking in the past of our galaxy, each of which included 10 million or more stars, and their remains are just waiting to be found in the globular intestines of our galaxy.
“The wreckage of more than five ancestral galaxies has already been identified,” Kruisen said. “With current and upcoming telescopes, it must be possible to find [evidence of] mole. “
Astronomers have about 3 or 4 billion years to understand it. Then another merger will occur, changing the galaxy when the neighboring one Andromeda Galaxy (currently 2.5 million light-years away) and the Milky Way will inevitably collide. Isn’t that always the case: Just when you think you know a galaxy, it goes and changes on you again.
Originally published in Live Science.