The Milky Way appears to have a giant ripple that extends across at least a quarter of its disk. However, scientists have never confirmed this and some claim it doesn’t exist at all. However, if it does exist, it could have been created in a collision with another galaxy.
Eloisa Poggio of France’s National Center for Scientific Research in Nice and her team say they have noticed a faint ripple in the galaxy spreading away from its center. “It’s not huge, it’s just a small ripple,” Poggio said. New scientist.
The team made the observation after studying the motion of tens of thousands of stars using the Gaia space telescope. Several other waves have been discovered before, but the latest wave spreads across a huge part of the galaxy, she says.
In images, the Milky Way appears as a flat disk with a bulge in the middle. However, scientists have found small ripples in small parts of the galaxy, apparently caused by clouds of stars and gas. The disk is warped into a static S-shape.
Poggio and her colleagues studied two groups of stars to learn more about ripples in the galaxy. They observed how two different groups of young stars, which had only recently formed, moved with their surroundings. They compared the vertical and horizontal positions of these two groups of stars and their motion with a model of the galaxy. The shape of the model used showed a static S-shaped deformation.
What did the study reveal?
They noticed two different patterns of motion of the group of stars – back and forth along the galaxy’s radial axis and up and down. However, the two motion patterns were statistically related. The researchers concluded that the two motions are likely part of a single large wave. What caused the wave is not clear, although Poggio suspects it may have occurred after an earlier close encounter with the gravity of a smaller galaxy.
Other experts, however, say they see no connection between the two movements. Ralph Schoenrich of University College London said New scientist that instead of one big wave there could be two waves.
The star groups move horizontally and vertically, meaning the two waves could also be moving in the same direction. One or more past events likely caused the waves, although it’s impossible to say for sure that they’re part of a single wave, he says.
Further research is needed to better understand the observations.
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