Our Milky Method galaxy and Andromeda are destined to collide with one another in roughly 5 billion years, however the galaxies could already be exchanging stars.A brand new examine means that hypervelocity stars—people who journey in extra of 1,000 kilometers per second—may generate sufficient velocity to flee their house galaxy and journey to a different.These intergalactic travels are merely a stellar prelude to the huge smash-up in our galaxy’s future.Lots goes to be occurring in our neck of the universe in about 5 billion years.For one, our star will formally enter its purple large section—a climactic second that has the unlucky aspect impact of destroying Earth. However that received’t be the one massive change. In about that very same timeframe (give or take half a billion years), the Milky Method galaxy may also collide with Andromeda, which is able to type not a spiral, however a brand new elliptical galaxy some astronomers name “Milkdromeda.”Don’t fear, we now have a number of billion years to workshop the title.Whereas this slow-motion galactic collision continues to be a great distance off off, some scientists counsel that the Milky Method and Andromeda could already be exchanging stars. In a brand new paper, uploaded final week to the arXiv preprint server, Lukas Güzlow from the Karlsruhe Institute of Expertise in Germany argues that sure stellar objects often called “hypervelocity stars,” or HVSs, perhaps have already traveled the huge distances between our two galaxies.“Hypervelocity stars are among the quickest objects within the Galaxy,” the paper reads. “A few of them exceed escape velocity and are unbound to the Milky Method gravity. Primarily based on latest Gaia observations, a lot of them may have extragalactic origins.”First predicted by stellar dynamicist Jack Gilbert Hills in 1988, HVSs are stars with velocities exceeding 1,000 kilometers per second, or roughly 621 miles per second. Our solar, for instance, travels a measly (comparatively talking) 200 kilometers per second. Quick ahead 17 years after Hills’ preliminary predictions, and the primary HVS was found escaping the Milky Method. Since then, we’ve solely discovered extra. In 2021, for instance, the Nationwide Astronomical Observatories of China introduced the invention of 591 high-velocity stars—43 of which shifting into the hypervelocity realm able to escaping the galaxy.The trajectories of those stars counsel that they originate close to the galactic heart, had been they’re probably fashioned from interactions between binary stars and supermassive black holes. One other doable origin story is that one star in a binary star system goes supernova, which sends its orbital companion on a high-speed trek throughout the universe. Whereas many of those stars’ trajectories point out that they’ve punched a one-way ticket out of the Milky Method, the trajectories of another HVSs counsel extragalactic origins.To research this chance, Güzlow used Gaia area observatory information to calculate the trajectories of 18 million HVSs underneath two totally different eventualities—one wherein two galaxies had been of equal mass, and one other wherein one galaxy was simply half as huge as its counterpart. The beginning positions of the HVSs had been randomly generated close to the middle of Andromeda, and a small, non-zero share made their solution to our galactic neighborhood—outlined as roughly 50 kiloparsec radius from the Milky Method’s heart.Whereas most of the stars retain their preliminary velocity, the journey between galaxies takes so lengthy that some stars transition out of their most important sequence (a.okay.a. stars that fuse hydrogen like our Solar) state. A few of these stars will lose sufficient velocity to be captured by the Milky Method.“To seek out out whether or not hypervelocity stars from Andromeda can attain the Milky Method, we now have developed a simulation mannequin of the gravitational system of the 2 galaxies,” the paper reads. “Solely a small fraction of HVSs ejected from Andromeda are anticipated emigrate to the Milky Method. Nonetheless, it is likely to be doable to detect them primarily based on their velocity and trajectory orientation.”For now, Andromeda and the Milky Method are exchanging HVSs as a type of pleasant reward amongst galactic neighbors, however this stellar back-and-forth is barely a prelude to the galaxy-altering smash-up some 5 billion years from now.You May Additionally Like