(ORDO NEWS) — Ten billion years ago, the Milky Way swallowed up another galaxy. This was possibly the largest collision in the history of the Milky Way, and it makes our galaxy special. The remains of the “swallowed” system still rest in the center of the Milky Way.
This discovery is described in a scientific article published in the Monthly Notices of the Royal Astronomical Society.
Astronomers have studied many stars in the central region of the Milky Way and found something strange.
“Of the tens of thousands of stars we observed, several hundred were strikingly different from the rest in chemical composition and speed,” says the first author of the article, Daniel Orta-Darrington of John Moores University of Liverpool. “These stars were so different from others that they could be just from another galaxy.”
This galaxy, which once collided with ours, astronomers named Hercules. According to experts, the total mass of its stars was about 500 million suns. This is about twice as much as in the “sausage” galaxy Gaia-Enceladus, the collision with which until recently was considered the largest in the history of the Milky Way.
The merger with Hercules happened 10 billion years ago. The Milky Way was barely born then. Experts believe that a collision with such a large galaxy like Hercules at the very beginning of life is extremely rare. It makes the Milky Way unique among other spiral galaxies.
According to the calculations of scientists, Hercules left a noticeable mark in the history of the Milky Way. About a third of the stars in the rarefied spherical component of the Galaxy we got from this dead star system.
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