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The long-held belief that the Milky Way, home to Earth and our solar system, is relatively static has been dispelled. In a violent and dynamic dance between two galaxies, the dark matter halo of the Large Magellanic Cloud (LMC) – a hundredth satellite galaxy as massive as the Milky Way, visible as a light cloud in the night sky of the southern hemisphere – as observed by its namesake, 16th century Portuguese explorer Ferdinand Magellan – pulls and twists the Milky Way’s spiral-shaped disc of stars and planets at 115,200 kilometers per hour towards the constellation Pegasus.
“This discovery definitely breaks the spell that our galaxy is in some kind of state of equilibrium. In fact, the recent infiltration of the LMC is causing violent disturbances on the Milky Way, ”said Jorge Peñarrubia, personal chair of gravitational dynamics, School of Physics and Astronomy at the University of Edinburgh. “Understanding these elements can give us an unprecedented view of the distribution of dark matter in the two galaxies.”
Scientists believe that the LMC (image below) crossed the border into the Milky Way around 700 million years ago – recent by cosmological standards – and that due to its high dark matter content, it strongly disrupted the fabric and movement of our galaxy. The effects are still being seen today and should force a review of how our galaxy evolved, according to astronomers at the University of the University of Edinburgh, who found to their surprise that the Milky Way was not moving. not to the current location of the LMC, as previously thought. , but towards a point in its past trajectory.
Using a sophisticated statistical model, the Edinburgh team calculated the velocity of the stars farthest in the Milky Way, the University of Edinburgh team discovered how the LMC distorted the motion of our galaxy. They discovered that the LMC, powered by its massive gravitational force, is moving away from the Milky Way at an even faster speed of 370 km / s, or about 1.3 million km / hour.
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An earlier study done in 2007 by the Harvard-Smithsonian Center for Astrophysics suggested that there are two possible explanations for these high speeds. First, the Milky Way’s mass expanse is greater than previously thought. If the CML is gravitationally related to the Milky Way, then the Milky Way must be much more massive than previous data suggested. The excess mass would pull on the LMC, keeping it “at hand”. Second, CML is linked by gravity to the Milky Way. If the previous calculations of the Milky Way’s mass are correct, then the Milky Way is not massive enough to hold onto its companions. In a few billion years, it will escape the Milky Way.
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The LMC and its companion, Small Magellanic Cloud (SMC), may not be true Milky Way companions, but may be travelers passing through the neighborhood, astronomer Nitya Kallivayalil suggested to the Harvard-Smithsonian. Center for Astrophysics.
Astronomers now intend to find out the direction from which the LMC first fell in the Milky Way and the exact time it happened, which will reveal the amount and distribution of the dark matter in the Milky Way and the LMC with unprecedented detail.
“Our findings involve a new generation of Milky Way models to describe the evolution of our galaxy,” said lead author Michael Petersen. “We were able to show that stars at incredibly large distances, up to 300,000 light years away, retain a memory of the structure of the Milky Way before the LMC fell and form a backdrop against which we measured the stellar disk flying in space, pulled by the gravitational force of the LMC. “
The first accurate 3D map of the Milky Way shown at the top of the page reveals its true form: warped and twisted. Astronomers from Macquarie University and the Chinese Academy of Sciences have used 1339 “standard” stars to map the actual shape of our home galaxy. Artist’s impression above of the warped and twisted disk of the Milky Way. (Chen Xiaodian)
The Daily Galaxy, Sam Cabot, via University of Edinburgh
Image credits: LMC via Harvard CfA
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