ESA/GAIA/DPAC, S. Payne-Wardenaar, E. Poggio et al (2025)
Our galaxy, the Milky Way, is never stopped: spins and oscillates. And now, data from ESA’s Gaia Space Telescope reveal that our galaxy also has a giant wave that waves from its center out.
About a hundred years ago we know that the galaxy stars have revolved around their center and Gaia measured their speeds and movements. Since the 1950s we have known that the Milky Way album has been deformed. Then, in 2020, Gaia found that this album oscillates over time, similarly to the movement of a top.
And now it has become clear that a large wave shakes the movement of the stars of our galaxy over tens of thousands of light years of the sun. Like a stone thrown to a lake, ripping out, this galactic wave of stars encompasses a large part of the outer album of the Milky Way.
Even if no spaceship can travel beyond our galaxy, The exceptionally accurate view of Gaia – in the three space directions (3D) And at the three speeds (moving toward us and away from us, and through the sky)-they are allowing scientists to make these maps from top to bottom and sideways.
From them, we can see that the wave extends through a huge portion of the galactic album, affecting stars at least 30-65 thousand light years away from the center of the galaxy (for comparison purposes, the Milky Way is about 100,000 light years in diameter).
“What makes this even more convincing is the our ability, thanks to Gaia, to also measure the movements of the stars within the galactic album“Says Eloisa Poggio, inaf (Istituto Nazionale di Astrophysic) astronoma in Italy, who led the team of scientists who discovered the wave.
“The intriguing part is not only the visual aspect of the wave structure in the 3D space, but also its behavior wave when we analyze the movements of the stars inside. ”
“This observed behavior is consistent with what would be expected from a wave,” explains Eloisa.
Think of a “Wave” performed by a crowd at a stadium. Given that the galactic time scales are much longer than ours, imagine seeing this wave at the stadium stopped in time, as we observed the Milky Way. Some individuals would stand, others would have just sat down (when the wave passed) and others would be preparing to get up (when the wave approached them).
In this analogy, people who are standing correspond to the colorful regions red in the maps seen from face and side. And if we consider the movements, individuals with the highest positive vertical movements (represented by the largest white arrows to point up) are those who are starting to get up in front of the approaching wave.
Eloisa and her colleagues managed to discover this surprising movement studying the POSITIONS AND DISCLUDED POSITIONS AND MOVEMENTS OF YOUNG GIVE STARS and stars cefeid. The latter are stars that vary from brightness in a predictable way and can be observed by telescopes like Gaia at great distances.
Given that the young giant and cefeid stars move with the wave, the Scientists think that the gas on the disc may also be participating in this large scale ripple. It is possible for young stars to retain the memory of the wave from the gas in which they were born.
Scientists do not know the origin of these Galactic Abanions. A collision passed with a dwarf galaxy could be a possible explanation, but scientists need more investigations.
The large wave may also be related to a smaller-scale wave movement observed at 500 light years from the sun and extends to 9000 light years, the so-called Radcliffe wave.
“However, the Radcliffe wave is a much smaller filament And it is located in a different part of the galaxy album, compared to the wave studied in our work (much closer to the sun than the big wave). Both waves may or may not be related. That’s why we would like to do more research, ”adds Eloisa.
“Gaia’s fourth data release will include even better positions and movements from the Milky Way stars, including variable stars such as cefeidas. This will help scientists make even better maps, thus advancing in our understanding of these characteristics of our Christmas galaxy,” says Johannes Sahlmann, ESA Gaia Scientist.
