This hot “stream” of star gas will collide with our galaxy sooner than we thought.


The Milky Way plays a violent game of tug of war with its two toughest neighbors – the rowdy dwarf sister galaxies known as the Large and Small Magellanic Clouds. It is not a fair competition. With a combined weight of around 17 billion solar masses (nearly 100 times leaner than the Milky Way), the two dwarf galaxies are slowly being torn apart by the gravity of our galaxy, and by each other.

Over 3 billion years of this cosmic push and pull left a huge battle scar stretched across the southern sky – a long arc of gas known as the Magellanic Stream, trailing behind the Magellanic Clouds like a drop of water. stellar blood. One day, this stream will collide with our galaxy, flooding the Milky Way with star gas and constantly changing the landscape of the night sky.

That day might be sooner than we thought.

According to a new study published on November 8 in Letters from the astrophysical journal, the Magellanic Stream is much closer to our galaxy than previous estimates suggested. Based on recent observations of the stream’s structure, a team of researchers simulated the history of the interactions of large and small Magellanic clouds with each other and with our galaxy. They discovered that the stream contained only 65,000 Light years Earth – or about five times closer than previously thought.

The implications for the Magellanic Stream and its future are enormous; not only do these findings suggest that the flux is about a fifth more massive than previously thought, but also that it will collide with our galaxy much sooner – likely in around 50 million years, the researchers wrote. .

“What is surprising is that the models brought the flow much closer to [our galaxy]”, lead author of the study Scott Lucchini, graduate student in physics at the University of Wisconsin-Madison, said in a press release. “We now see that the flow is basically at the outer part of the Milky Way’s disk.”

A view from the Hubble Space Telescope of the Large Magellanic Cloud (blue clouds on the left). (Image credit: NASA Goddard)

These new estimates of the location of the flow are based on research published last year in the journal Nature. (Lucchini was also the main author of this article). In this study, researchers found that the Large Magellanic Cloud is surrounded by a “halo” of hot ionized gas reaching temperatures of around 900,000 degrees Fahrenheit (500,000 degrees Celsius) – or about half to one sixth from the heat of the outermost layer of our sun. The team named this hot sheath the Magellanic Crown.

The existence of the crown changes the history of the formation of the Magellanic clouds and the stream. The hot, gaseous sheath around the larger cloud adds to the total mass of the dwarf galaxies, and it is expected to dramatically increase the friction and pressure on both galaxies as they move around the corona, the researchers wrote.

With these forces in mind, the team developed a new computer simulation to model the history of the Magellanic Clouds and the Magellanic Current. The team worked backwards, starting with the current cloud locations and moving back in time through multiple simulations to show how dwarf galaxies could have interacted over eons in order to end up where they are. now.

The team found that the two dwarf galaxies had been orbiting each other for only about 3 billion years. By the time both galaxies were captured by the Milky Way, the Small Magellanic Cloud was spinning counterclockwise around the Large one, spewing gas behind it and forming the Magellanic Current. Unlike previous studies, the team’s simulations also showed that the current was heading toward, rather than away from, the Milky Way, with the two celestial bodies only 65,000 light-years away at their closest point. . (The clouds themselves live much further away, about 180,000 and 200,000 light years from Earth, respectively).

“The revised distance changes our understanding of flow,” study co-author Andrew Fox, a researcher at the Space Telescope Science Institute in Maryland, said in the statement.

This means everything scientists thought they knew about the flux needs to be reassessed, including when our galaxy devours it completely, giving the Milky Way another injection of star gas. Any form of life on Earth tens of millions of years from now may look up to see a sky completely different from ours – but for now we’ll just have to enjoy the gentle slow-motion tug of war that takes place over our heads.

Originally posted on Live Science.

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