In its early days, the milky Way, absorbed small galaxy, and star of his unfortunate victims still wander the sky telling their story, scientists have reported. “This is a great event for the history of the galaxy,” says astronomer Amina Helmi of the University of the Diamond in the Netherlands. “We are just starting to explore the ancestors of the milky Way.” Helmi and her colleagues analyzed the speed and position of tens of thousands of stars in the milky Way in the range of 33 000 light years from the sun, using data from the Gaia space telescope belonging to the European space Agency. A group of 30 000 stars appears to be moving back that scholars wrote on October 31 in the journal Nature. Instead revolve around the galactic center with the sun and the other stars on the bright disk of the milky Way, these stars are moving in the opposite direction.
“It was the first hint,” says Helmi. “When the stars are moving in the opposite direction, it suggests that they were formed there and not in a way that most stars in our galaxy.”
The second hint came from the search of these stars in the catalog of the experiment APOGEE, which takes the basis of spectrum of light of stars, to understand their chemical composition and age. The moving back was less heavy elements than stars like the Sun. This suggests that they formed early in the history of the universe, before the time of massive stars and supernovae distribute heavy elements through the galaxy.
The milky Way — the galaxy eater
This chemical composition strengthened the confidence of scholars. Once 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 to five times smaller than the milky Way at the time, containing 600 million stars with the mass of the Sun.
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