Space Research

Collision with a dwarf galaxy billions of years ago reshaped the Milky Way, study claims

If a new research study is to be believed the Milky Way had a massive head-on collision with a dwarf galaxy, dubbed the “Gaia Sausage” galaxy, billions of years ago, leaving behind a mess of stars.

According to the research study conducted by an international team of astronomers, the dwarf galaxy did not survive the collision and fell apart in no time providing extra gases to fuel star formation.

“The collision ripped the dwarf to shreds, leaving its stars moving in very radial orbits that are long and narrow like needles,” said Vasily Belokurov of the University of Cambridge and the Center for Computational Astrophysics at the Flatiron Institute, New York. “The stars’ paths take them very close to the center of our Galaxy. This is a telltale sign that the dwarf galaxy came in on a really eccentric orbit and its fate was sealed.”

For the purpose of the study, the research team studied a sample of around 200,000 main sequence stars using data from the European Space Agency’s Gaia spacecraft and the Sloan Digital Sky Survey. The Gaia spacecraft has been mapping our galaxy as well as recording the journeys of stars as they travel through the Milky Way. The researchers used mathematical models to rewind and unravel the path of the stars.

Cambridge University astronomer Wyn Evans claims that the paths of the stars from the galactic merger earned them the moniker the “Gaia Sausage”.  The Sausage galaxy is believed to be more than ten billion times the mass of the Sun.

As per the findings, when the dwarf galaxy crashed into the young Milky Way, its piercing trajectory caused a lot of mayhem. The collision almost reshaped the Milky Way’s disk. The resulting debris that scattered all around the inner parts of the Milky Way is believed to have created the bulge at the Galaxy’s center and the surrounding ‘stellar halo.’

The study also identified eight large, spherical globular clusters that were brought into the Milky Way by the Sausage galaxy.

The research has been published in the Monthly Notices of the Royal Astronomical Society.

About the author

Megha Kedia

Megha Kedia

Megha is a seasoned reporter with over six years of experience covering news in technology, science and related fields. At The Space News, Megha covers space research & technology news.

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