The Large and Small Magellanic Clouds are two of the most rowdy dwarf galaxies and the Milky Way is playing a violent game of tug-of-war with them. It's not a fair contest. The two dwarf galaxies are being torn apart by the gravity of our galaxy, and are nearly 100 times scrawnier than the Milky Way.
An enormous battle scar stretching across the Southern sky is the result of 3 billion years of pushing and pulling. One day, this stream will collide with our galaxy, causing a huge flood of gas and changing the landscape of the night sky.
That day may be sooner than we thought.
The research published in The Astrophysical Journal Letters states that the Magellanic Stream is far closer to our galaxy than had been thought. A team of researchers simulations the history of the Large and Small Magellanic Clouds' interactions with each other and with our galaxy after accounting for recent observations of the stream's structure. The stream is just five times closer to Earth than previously thought.
The findings suggest that the stream is about one-fifth as massive as previously thought, and that it will collide with our galaxy much sooner than previously thought.
Scott Lucchini, the lead study author and a graduate student in physics at the University of Wisconsin-Madison, said in a statement that the models brought the stream closer to our galaxy. The stream is located at the outer part of the disk of the Milky Way.
The Large Magellanic Cloud is seen in a Hubble Space Telescope view. The image is from NASA.
The new estimates for the stream's location are dependent on research published in the journal Nature. The lead author of that paper was Lucchini. The Large Magellanic Cloud is surrounded by a "halo" of hot, ionized gas, which is about one-half to one-sixth the heat of our sun's outermost layer. The team named the hot sheath after it.
The corona's existence changes the story of the Magellanic Clouds. The researchers wrote that the hot, gassy sheath around the larger cloud adds to the total mass of the dwarf galaxies, and it should increase the pressure on the two galaxies as they move through the corona.
The team developed a new simulation to model the history of the Clouds and the Stream. The team worked backwards, starting with the current locations of the clouds and then using multiple simulations to show how the dwarf galaxies could have interacted over the eons in order to end up where they are now.
The two dwarf galaxies have been in close proximity for 3 billion years. The Small Magellanic Cloud was around the Large one in a circle, releasing gas behind it and forming the Magellanic Stream. The team's simulations showed that the stream is moving toward the Milky Way, rather than away from it, with the two bodies just 65,000 light-years away. The clouds are far away, at about 180,000 and 200,000 light-years from Earth.
Andrew Fox, a researcher at the Space Telescope Science Institute in Maryland, said in the statement that the revised distance changed their understanding of the stream.
Everything scientists thought they knew about the stream needs to be reexamined, including when our galaxy will fully devour it, giving the Milky Way a fresh injection of star-forming gas. We'll just have to enjoy the faint, slow-motion tug-of-war playing out above our heads, because any life-forms on Earth tens of millions of years from now may look up to see a sky completely different from our own.
Live Science published the original article.
