The Milky Way is in constant motion. It rotates, tilts slightly, and, as new observations show, it oscillates. Astronomers have discovered a gigantic wave moving through the outer regions of our galaxy. It appears to move similarly to waves on the surface of water.
Milky Way: A Stadium Wave Through Space
The structure was discovered by the European Space Agency’s (ESA) Gaia space telescope. The observatory has been measuring the positions and movements of billions of stars for years. The latest analyses have now shown that stars in the disk of the Milky Way move in a wave-like pattern, as the ESA explains in a statement.
The wave affects huge areas of the galactic disk. Stars are alternately located above and below the imaginary midplane of the Milky Way. “The intriguing part is not only the visual appearance of the wave structure in 3D space, but also its wave-like behavior when we analyze the motions of the stars within it,” says Eloisa Poggio from the Italian Istituto Nazionale di Astrofisica (INAF), who led the research team. The comparison of a “stadium wave” as earth.com puts it, is a great way to picture it. While some stars are already “standing up,” others “sit down” again as the wave passes by.
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Further Data Should Bring More Clarity
To make this discovery, the researchers primarily studied young giant stars and so-called Cepheids, which are variable stars whose brightness fluctuates regularly. These stars serve as beacons to determine distances in the Milky Way. They appear to move along with the wave. According to the research team, this suggests that the gas in the galactic disk also participates in this movement. Therefore, newly formed stars could carry the “memory” of the wave from which they originated.
Why the Milky Way exhibits this huge oscillation is still unclear. One possible explanation could be an old encounter with a smaller galaxy. Such collisions can trigger strong gravitational waves that cause the disk of the Milky Way to ripple. “One reasonable scenario is that a satellite galaxy generated these ripples and corrugations.,” Poggio told IFLScience. Similar effects can already be observed in computer simulations.
More data from the telescope is expected soon. “The upcoming fourth data release from Gaia will include even better positions and motions for Milky Way stars, including variable stars like Cepheids,” announced Johannes Sahlmann, an ESA project scientist. This could help astronomers better understand what set our galaxy in motion.
Sources: ESA, earth.com, IFLScience
This article was translated with the help of AI and carefully reviewed by our editorial team.