Streams of stars being swallowed by the Milky Way help to better understand dark matter

(ORDO NEWS) — Astronomers are one step closer to understanding the properties of the dark matter surrounding our Milky Way galaxy with a new map of 12 stellar streams circling within our galaxy’s halo.

Understanding these stellar streams is of great importance to astronomers. In addition to providing information about the dark matter that holds stars in their orbits, they can also tell the story of the formation of the Milky Way, showing that the Milky Way slowly grew over billions of years, tearing apart and swallowing smaller star systems.

“We are looking at how these streams are torn apart under the influence of the gravitational influence from the Milky Way and eventually become part of the Milky Way.

This study gives us an understanding of the “eating habits” of the Milky Way, that is, the nature of the star systems consumed by the Galaxy. As our galaxy ages, it “gets fatter,” said University of Toronto professor Ting Li, who is the lead author of the new study.

Professor Li and her international team launched a special program, the Southern Stellar Stream Spectroscopic Survey (S5), to study the properties of stellar streams, fragments of nearby small galaxies, and clusters of stars that have been torn apart by the Milky Way’s gravity.

The properties of stellar streams reveal the presence of invisible dark matter within the Milky Way. “Imagine a Christmas tree,” said co-author Geraint F. Lewis of the University of Sydney, Australia. – On a dark night, we see burning garlands, but not the tree itself on which they are hung.

But by the shape of the garlands, we can get an idea of ​​the silhouette of the tree itself. It’s the same with stellar streams – their orbits allow us to detect dark matter.”

In addition to measuring the speeds of stellar streams, astronomers can also use these observations to calculate the chemical composition of stars in order to determine the origin of the stars from this data.

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