There’s a giant ripple in our Milky Way galaxy that astronomers believe is the result of a collision with another galaxy.
The Milky Way, our galaxy, may be hiding a fascinating and mysterious structure: A giant ripple stretches across at least a quarter of its disk. The discovery, if confirmed, could be a remnant of an ancient collision with another galaxy. However, the astronomical community is divided over whether such a structure actually exists.
The theory was put forward by Eloïse Poggio, a researcher at the French National Center for Scientific Research (CNRS) in Nice, in a study recently published on the pre-print server arXiv. Our galaxy is usually represented as a flat disk with a bulge in the center, but its actual structure is much more complex. Astronomers have mapped clouds of stars and gas moving in waves through different sections of the Milky Way, revealing that the galaxy’s disk is not flat, but slightly twisted, resembling the letter “S” when viewed from the side.
What does the new study say?
In the new study, Poggio and his team discovered a faint ripple spreading far from the galaxy’s center by analyzing the motions of tens of thousands of stars captured by the Gaia space telescope. “It’s not huge, it’s just little ripples,” Poggio says. But unlike previously detected waves, this one extends over a large portion of the galaxy.
one giant wave
The researchers studied the movements of two groups of young, newly formed stars that were still moving in tune with their surroundings. By comparing their positions and vertical and horizontal motions with a model of the Milky Way that reflects our current understanding of its shape, the researchers identified two patterns of motion: one along the radial axis of the galaxy and one up and down, as viewed from the side. These patterns were statistically correlated, suggesting that they may be part of a single, larger wave.
Collision with another galaxy?
The origin of this ripple remains a mysteryHowever, Poggio speculates that the cause could be a close encounter with the gravity of a smaller galaxy in the past. This hypothesis could open new avenues in studying the history of the Milky Way and past interactions with other galaxies.
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