New data from the European Space Agency's Gaia space telescope shows that the galaxy is not only spinning but also wobbling, with a giant wave extending from its center, spanning tens of thousands of light-years.
A wave passing through the galactic disk causes millions of stars to move up and down, like ripples on water. Astronomers suggest that even interstellar gas participates in this movement.
Researchers have known for nearly a century that the stars of the Milky Way revolve around a center. And since the 1950s, it has become clear that the galactic disk is not flat but slightly curved. In 2020, Gaia discovered that this curved disk also oscillates slowly like a flat surface. Now, telescopes have helped distinguish a real “galactic wave.”
This wave affects stars located at a distance of 30 to 65 thousand light years from the center of the Milky Way. For comparison, the diameter of our entire galaxy is about 100,000 light-years.
“We were surprised by its wave-like behavior, which is visible when you analyze the motion of stars,” said Eloisa Poggio, an astronomer at the National Institute of Astrophysics in Italy who led the study.
The scientist compared this phenomenon to the “wave” that fans create at the stadium. At one point, some people are standing, others are just sitting down, and still others are preparing to stand up. In the galaxy, everything happens much slower, but the principle remains the same.
Eloise and her team discovered this motion by studying young giant stars and Cepheids, a special type of star whose brightness changes predictably. This allows them to be accurately tracked even over vast distances. Because these stars move in waves, researchers believe that the gas from which they are born also participates in this movement.
Why the galaxy “wobbles” like this is not exactly known. One version is an ancient collision of the Milky Way with another, smaller galaxy. But more research is needed to confirm this. The new “big wave” may be linked to another structure – Radcliffe waves, much closer to the Sun.
“However, the Radcliffe waves are smaller and located in a different part of the galactic disk,” said Eloisa Poggio. – These two waves may or may not be connected. We plan to find out.”
Scientists plan to create more detailed maps using the Gaia telescope to better understand the unique features of our stellar home.
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