Milky Way
NASA satellite to study Milky Way's halo. Pictured, an artist's concept illustrating the new view of the Milky Way, along with other findings presented at the 212th American Astronomical Society meeting in St. Louis, Missouri. The galaxy's two major arms (Scutum-Centaurus and Perseus) can be seen attached to the ends of a thick central bar, while the two now-demoted minor arms (Norma and Sagittarius) are less distinct and located between the major arms. NASA/JPL-Caltech

A new study revealed that Milky Way has already devoured a number of galaxies as it’s currently in the process of colliding and merging with another galaxy.

According to the authors of the study, it was previously believed that Milky Way was on a collision course with its neighboring large dwarf galaxy known as the Large Magellanic Cloud (LMC).

Located about 163,000 light-years from Milky Way, the LMC started approaching the galaxy 1.5 billion years ago. Scientists noted that the LMC will collide with Milky Way in about 2 billion years.

However, using the European Space Agency’s Gaia space telescope, a team of researchers discovered that the collision between the LMC and Milky Way may have already started. The researchers came up with the conclusion after discovering traces of small galaxies within Milky Way. According to the researchers, these galaxies once belonged to the LMC.

According to Laura Sales, the lead author of the study, the researchers’ latest discovery suggests that Milky Way may have had a totally different composition before it started devouring the galaxies from the LMC.

“If so many dwarfs came along with the LMC only recently, that means the properties of the Milky Way satellite population just 1 billion years ago were radically different, impacting our understanding of how the faintest galaxies form and evolve,” she said in a press release.

Sales’ co-author Ethan John noted that given the mass of the LMC, the Milky Way could be going through the largest galactic merger in its history.

“The high number of tiny dwarf galaxies seems to suggest the dark matter content of the LMC is quite large, meaning the Milky Way is undergoing the most massive merger in its history, with the LMC, its partner, bringing in as much as one third of the mass in the Milky Way’s dark matter halo — the halo of invisible material that surrounds our galaxy,” Jahn explained.

The findings of the researchers were presented in a new study published in the Monthly Notices of the Royal Astronomical Society. It will be featured in the online journal’s November 2019 issue.

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