The Milky Way galaxy ate a smaller 10 billion years ago
In his early days of the Milky Way galaxy swallowed small, and the star of his unfortunate victims are still wandering in the sky, telling their stories, scientists report. "This is a great event for the history of the galaxy," said astronomer Amina Helmi of the University of Groningen in the Netherlands. "We are just beginning to explore the ancestors of the Milky Way." Helmi and her colleagues analyzed the position and velocity of tens of thousands of stars in the Milky Way within 33,000 light-years from the sun, using the Space Telescope data Gaia, a European Space Agency. A group of 30 000 stars, seems to be moving backwards, as scholars have written on October 31 in the journal Nature. Instead of rotating around the galactic center with the sun and the other stars on the bright disk of the Milky Way, the stars are moving in the opposite direction.
"This was the first hint," said Helmi. "When the stars are moving in the opposite direction, it suggests that they were formed and there is not not how the majority of stars in our galaxy." The second hint came from a search of these stars in the APOGEE experiment directory that builds on the spectrum of starlight in order to understand their chemical composition and age. In moving in the opposite direction was less heavy elements than the Sun-like star. This suggests that they were formed early in the history of the universe, even before it's time, massive stars and supernovae, spreading heavy elements around the galaxy.
The Milky Way - devourer of galaxies
This chemical compound added to the confidence of scientists. Immediately it became clear that they were formed somewhere else.
Comparing the observations with computer models, the team Helmi came to the conclusion that 10 billion years ago the Milky Way collided with a smaller galaxy, perhaps four or five times less than the Milky Way at the time, containing 600 million stars with the mass of the sun.
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