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TheMilky Waycontains more than 100 billion whizz , but it did n’t come by them all candidly . At least a twelve times over the last 12 billion twelvemonth , theMilky Waycollided with a neighboring beetleweed and down it , swallowing up that neighbor ’s stars and mixing them into an ever - growing swither of pilfered suns .
With each galactic unification , the shape , size and motion of our galaxy changed forever , ultimately becoming the iconicspiralwe recognize today . Now , in a recent written report published in the October 2020 issue of the journalMonthly Notices of the Royal Astronomical Society , researchers have attempted to unwind that spiral . Using artificial intelligence ( AI ) to match decided clustering of star by their ages , motions and chemical compositions , the team find evidence of five large - scale galactic mergers ( each involving 100 million stars or more ) dating back more than 10 billion years — including one ancient hit that has never been described before .
A globular cluster (yellow) glows in the Large Magellanic Cloud, one of the Milky Way’s smaller satellite galaxies. Astronomers studied clusters like these to recreate the ancient mergers that made the Milky Way what it is.
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This newfound crash with the so - called Kraken beetleweed not only helps fill in the Milky Way ’s mysterious home tree diagram , but could also help astronomers piece together what our galaxy reckon like in its earliest days , the work author said .
" The collision with Kraken must have been the most meaning merger the Milky Way ever experient , " lead study author Diederik Kruijssen , an astronomer at the University of Heidelberg in Germany , sound out in a statement . " The merger with Kraken took lieu 11 billion old age ago , when the Milky Way was four times less massive [ than today ] . As a result , the hit must have sincerely translate what the Milky Way looked like at the metre . "
An image from the new study shows the five major mergers that made the Milky Way what it is today.
In their new study , Kruijssen and his colleagues used computer simulation to analyze all the knownglobular bunch — old , dense spheres of up to 1 million stars that all forge around the same time as each other — within the Milky Way . Our galaxy hosts at least 150 of these clusters , which astronomers consider are " fossils " of the ancient galaxies that the Milky Way gobbled up over its long and athirst chronicle .
The researcher trained an AI algorithm to name globular clusters base on the shared properties of stars , at first start the algorithm on thousands of simulated galaxies . Once the algorithm was capable to accurately predict the formation , organic evolution and wipeout of globular clusters in those imaginary galaxies , the team coiffe their AI at large on the Milky Way .
Using datum obtained by the Gaia space probe ( which has given us themost ended single-valued function of the Milky Way ) , the algorithm analyzed the ages , movement and chemical compositions of known globular clusters in our galaxy for recreate the cosmic amalgamation that land them there . The team ’s analysis accurately predicted four known mergers in the Milky Way ’s yesteryear — include the so - calledGaia sausagemerger , which add up several billion stars to our galaxy ’s bulge about 9 billion years ago — as well as the antecedently unknown Kraken merger .
And that merger was a beast . allot to the team ’s results , the Kraken may have been the largest and oldest galactic collision in the Milky Way ’s chronicle . The merger occurred when the Milky Way was only a fraction of its current sizing , and may have added to our coltsfoot 13 globular clusters that are still identifiable today . While the Gaia sausage merger at last added more solar great deal to the Milky Way ( more than 20 orbicular cluster ' worth ) than did the Kraken one , our wandflower was considerably bigger when the blimp merger happened and was probably less susceptible to major morphological change , the researchers drop a line .
This newfound merger is only one small spell of the puzzle . Because the route to galaxy formation is strewn with collisions like these , it ’s likely that many more low - scale mergers also contributed to the Milky Way we know today . Astronomers surmise that at least 15 other mergers may be loaf in our galaxy ’s past tense that each involve 10 million stars or more , and their remnants are just waiting to be ground in our extragalactic nebula ’s globular guts .
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" The debris of more than five progenitor galaxy has now been describe , " Kruijssen suppose . " With current and coming telescopes , it should be possible to detect [ grounds of ] them all . "
Originally published on Live Science .
