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The long lost brother of the Milky Way was shredded and devoured by our closest closest galactic neighbor – the Andromeda galaxy – about two billion years ago, discovered scientists. The massive galaxy, though mostly jagged, left behind a rich trace of evidence – an almost invisible halo of stars larger than the Andromeda galaxy itself, and a separate compact galaxy M32. This disturbed galaxy was the third largest member of the local group of galaxies, after the galaxies of the Milky Way and Andromeda.
Richard D & Souza and Eric Bell, of the University of Michigan in the United States, used computer models. together this evidence, revealing this long-lost brother of the Milky Way. Scientists have long known that this large almost invisible star halo surrounding galaxies contains the remains of smaller cannibalized galaxies. A galaxy like Andromeda would have consumed hundreds of its smallest companions. The researchers thought that it would make it difficult to learn from one of them.
Scientists have found that although many associated galaxies were consumed by Andromeda, most of the low halo stars of Andromeda were mainly composed of only one large fragment. galaxy. "We realized that we could use this information from Andromeda's outer stellar halo to infer the properties of the largest of these jagged galaxies," said Dr. Souza, lead author of the published study. in the journal Nature Astronomy. .
"Astronomers have been studying the local group for so long – the Milky Way, Andromeda and their companions – and it is shocking to realize that the Milky Way has a big brother, and we never knew it," said Bell. This galaxy, called M32p, which was shredded by the Andromeda galaxy, was at least 20 times larger than any galaxy that merged with the Milky Way during its lifetime.M32p would have been massive, which in turn made the third largest local group galaxy after the Andromeda and Milky Way galaxies
This work could also solve a long-standing mystery: the formation of Andromeda's enigmatic satellite galaxy M32, say the scientists. They suggest that the compact and dense M32 is the surviving center of the lost brother of the Milky Way, as the indestructible pit of a plum. "While it (M32) looks like a compact example of an old elliptical galaxy, it really has a lot of young stars, it's one of the most compact galaxies in the world." 39, universe, there is not another galaxy like that ".
The study could alter the traditional understanding of the evolution of galaxies, according to the researchers. They realized that the Andromeda disk survived an impact with a massive galaxy, which challenged the common wisdom that such interactions would destroy the disks and form an elliptical galaxy.
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