The Milky Way is ‘rippling’ like a pond, and scientists may finally know why
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Imagine the 100 billion stars of the Milky Way as flat, still puddles. Now imagine someone dropping a stone the size of his 400 million suns into that water. The stillness is shattered. Wave after wave of energy ripples across the surface of the galaxy, pushing and bouncing the stars in a chaotic dance that takes many years to subside.
Astronomers think something like this may have actually happened not just once, but several times over the past billion years.
In a new paper published on September 15th Monthly Notices of the Royal Astronomical Societyresearchers found a nearby small galaxy – the Sagittarius dwarf galaxy — seems to have collided milky way Caused a star here and there on at least two separate occasions galaxy It mysteriously vibrates at different speeds.
Related: Largest galaxy ever discovered baffles scientists
Using data from the European Space Agency’s Gaia Space Observatory, researchers compared the movements of more than 20 million stars across the Milky Way, specifically in the outer region of the Galactic disk. The data revealed mysterious ripples, or oscillations, that appear to crush stars across the galaxy.
Study author Paul McMillan, an astronomer at Lund University in Sweden, said: said in a translated statement.
Through a process the researchers have identified as “galactic seismology,” the team modeled waveform patterns that could explain the strange ripple effects that destabilize the stars of the Milky Way. They concluded that the ripples were likely emitted hundreds of millions of years ago when the Sagittarius dwarf galaxy last passed through our galaxy. A second, even earlier collision between the two galaxies likely also occurred, the researchers added.
Previous research (opens in new tab) Suggesting that an ancient collision with Sagittarius may have caused ripples at the center of the Milky Way, this new study suggests that those ripples extend to the edge of the galactic disk, smashing stars at every step. This new study should help piece together the long and violent history of our galaxy and its smaller neighbors.
Today, the Sagittarius dwarf galaxy is estimated to be about 400 times more massive than Earth’s Sun. This is a mere shrimp compared to the Milky Way Galaxy’s estimated mass of 1.5 trillion suns. Scientists believe that Sagittarius was once much bigger, but has lost up to 20% of its mass to the galaxy after repeated collisions over the past billion years.
These collisions may have also changed the shape and size of galaxies. A 2011 study suggested that the Milky Way’s spiral arms were the result of her two collisions with the Sagittarius dwarf galaxy. Another study of Gaia data published in 2020 found that a cosmic collision between our galaxy and the constellation Sagittarius caused a baby boom of new stars in the Milky Way every time the two galaxies met. was suggested.
Originally published in Live Science.
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