'Dark and Luminous:' The Milky Way Galaxy Is Kidnapping Smaller Galaxies as We Merge With the Large Magellanic Cloud

Friday, 11 October 2019 - 3:08PM
Friday, 11 October 2019 - 3:08PM
'Dark and Luminous:' The Milky Way Galaxy Is Kidnapping Smaller Galaxies as We Merge With the Large Magellanic Cloud
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NASA Goddard

The Milky Way has been "stealing" satellite galaxies as we merge with the Large Magellanic Cloud, amassing a collection of over fifty satellite galaxies orbiting around it according to breaking research coming from the University of California, Riverside. The research was published in the November 2019 issue of the Monthly Notices of the Royal Astronomical Society, and it has the most amazing title: "Dark and luminous satellites of LMC-mass galaxies in the FIRE simulations."

According to reports from SciTech, a team of scientists at UCR analyzed data from the European Space Agency's Gaia telescope and compared it to simulations, then calculated for variables like dark matter.

The data revealed something strange: six of the galaxies that orbit the Milky Way – including two that are fairly distinct – were actually pulled from the Large Magellanic Cloud. As we edge closer and closer to a galactic collision, the Milky Way's stronger gravitational force has been yanking smaller galaxies into its orbit, much like how planets orbit the Sun in our solar system.

That's not all. "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," added Ethan Jahn, a graduate student at UCR and first author on the paper.

Dwarf galaxies are the most common type of galaxy in the universe. They are, as you might expect, very small ­– containing no more than a few billion stars. (The Milky Way, by contrast, has anywhere between 200-400 billion stars.)

The Large Magellanic Cloud (LMC) is a large dwarf galaxy and one of the Milky Way's closest neighbors; you can see it on a clear night in the Southern Hemisphere. Astronomers love it for the highly active star-forming regions that make it light up with color.

And, according to computer simulations, it's on a collision course with the Milky Way. There's no need to fill out a change of address form just yet, however: scientists estimate it will be another 2.4 billion years before we have new neighbors.