The Milky Way, like many spiral galaxies, is made up of a dense central bulge and a large thin disk of stars. Recently we learned that this thin disc is not flat, but wrapped. Recent observations suggest that the strap revolves around the galaxy every 440 million years, somewhat like a stadium wave. The new findings were presented at the 237th meeting of the American Astronomical Society this week. It is feared that this was due to a collision between the Milky Way and a small galaxy. As the Sun moves around the Milky Way in 225-250 million years, stars larger than the Sun move up and down the thin disk plane every 440 million years.
Xinlun Cheng of the University of Virginia, the lead author of the study, said in a statement, “The normal image of our spiral galaxy is like a flat disk, thinner than a pancake and revolving peacefully around its center.” “But the reality is more complicated. Imagine you’re standing in a football game and the crowd starts to wave. All you have to do is sit up, but the effect is that the wave goes around the stadium: it’s the same as the galactic warp – the stars. Not only does it go up and down, but the wave travels all over the galaxy.”
As part of the Sloan Digital Sky Survey (SDSS), the Apache Point Observatory has collected data on thousands of stars from the Galactic Evolution Experiment (APOGEE). The team uses the spectrum of light from each star to recognize where that star came from. When it was combined with data from the European Space Agency’s Gaia observations, the team had a clearer idea of how the warp would move through the galaxy.
Dr. Borja Anguiano of the University of Virginia added, “Apogee Spectra provides information about the chemical makeup and motion of individual stars.” “This allows us to divide them into separate groups, which in turn allows them to follow the warp separately in each group of stars.”
This study estimated the speed and amplitude of the wave more accurately than before. Over the decades, it has been known that more than half of all spiral galaxies (probably up to seven out of 10) have rapped. Studying the Milky Way galaxies isn’t as easy as we’re at, but it’s important to understand us and other galaxies.