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In a computer simulation of the formation of spiral galaxies, a halo structure is formed partially from a stack of many small galaxies. Even after the disintegration of fused galaxies, individual stars retain chemical traces of their original galaxies.
Credit: Takayuki Saito / Takaaki Takeda / Project Sorahiko Nukatani / 4D2U, NAOJ
A star of the Big Dipper is an intergalactic extraterrestrial, based on clues from his chemical fingerprints.
The new chemistry reveals that the unusual chemistry of the star differs from that of all known stars of the Milky Way. It has more in common with the stars of neighboring dwarf galaxies.
The researchers suspected that the strange oddball, named J1124 + 4535, came from a dwarf galaxy that collided with the Milky Way a long time ago. According to this theory, when the dwarf galaxy collapsed, it blocked that star in our cosmic neighborhood. [11 Fascinating Facts About Our Milky Way Galaxy]
The star was discovered for the first time in the Ursa Major constellation in 2015 by China's LAMOST multi-object fiber spectroscopic telescope. High-resolution images were captured in 2017 by Japan's Subaru telescope, scientists said on April 29 in the journal Nature Astronomy.
Spectral readings from the star revealed that he was poor in metals such as magnesium, but that he had unexpected levels of europium, a heavy element; The researchers wrote a unique report of elements compared to the other stars of the Milky Way.
The elements in the stars reflect the composition of the clouds of dust and gas where the star is formed. Nearby stars are usually shaped by the same materials and therefore bear similar chemical signatures. When a star stands out from a group, scientists look elsewhere to see where she might have been born.
Previous studies have shown that the Milky Way is formed by clashing with small galaxies and absorbing them. Stars have reported that metal-poor stars such as J1124 + 4535 are common in dwarf galaxies orbiting the Milky Way, scientists said.
Their analysis of J1124 + 4535 provides "the clearest chemical signature" to date among the old galaxy fusions that shaped the Milky Way billions of years ago, according to the study.
And this is not the only cosmic evidence that suggests the tumultuous past of the Milky Way.
A distinctive bulge in the center of the Milky Way would be the result of a collision with a dwarf galaxy shaped like a sausage about 10 billion years ago. This event swelled the core of the Milky Way with an influx of billions of stars, some of the oldest of the universe.
It may be that the smashup is even more important in the future of the Milky Way: our galaxy is currently on a collision course with another spiral galaxy, the Great Magellanic Cloud. Fortunately, this will not happen for at least 2 billion years – and this collision takes place about 2 to 3 billion years before we plan to break into the Andromeda galaxy.
Originally published on Science live.
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