Five billion years ago small, short-lived galaxies played games of galactic bumper cars with each other, leaving debris in their aftermath. As the Milky Way began to form, it gathered some of the wayward fragments, which are now the ancient stars that roam its stellar halo, a new study by Durham University claims.
By running computer simulations to reenact the beginning and evolution of the universe, the researchers revealed that the ancient stars in our galaxy’s halo, or the sphere of matter and gas at the periphery of a galaxy, are relics of galaxies past.
Their simulations — the most realistic to date — produced images like the one shown, which is of a Milky Way-like galaxy it its infancy, a time when most galaxy collisions were occurring.
“Like ancient rock strata that reveal the history of Earth, the stellar halo preserves a record of a dramatic primeval period in the life of the Milky Way which ended long before the Sun was born,” said Andrew Cooper from Durham University’s Institute for Computational Cosmology and lead author of the study.
This research is part of the Aquarius Project, an endeavor by an international team of scientists to use large supercomputer simulations to study the formation of galaxies.