Devouring a Smaller Galaxy Gave Milky Way Its Size & Shape

Gaia’s all-sky view of our Milky Way Galaxy and neighboring galaxies, based on measurements of nearly 1.7 billion stars. The map shows the total brightness and color of stars observed by the ESA satellite in each portion of the sky between July 2014 and May 2016. (ESA via AP)

(CN) – The structure and size of the Milky Way is a direct result of our galaxy consuming a far smaller galaxy nearly 10 billion years ago, a study revealed Monday.

The study, published in the scientific journal Nature Astronomy, offered the discovery after researchers examined data from highly advanced stellar models and diagram fitting techniques. These kinds of models and techniques help to provide crucial info on the age and chemical history of nearby galaxies.

Carme Gallart, researcher at the Institute of Astrophysics of the Canary Islands and co-author of the study, used this data to make some significant observations on the history of the Milky Way and how it has expanded throughout its lifetime.

Most startling, Gallart’s team found that billions of years ago the Milky Way absorbed a nearby galaxy known as Gaia–Enceladus, a galaxy roughly one-quarter its size.

Gallart hopes this new research will help people to better understand how our galaxy came into being by providing new and clear information.

“This study has put in a clear temporal order the early sequence of events that shaped the Milky Way in its early years, providing a crystal-clear picture of what happened,” Gallart said.

Gallart’s team found that by absorbing its galactic neighbor, the Milky Way came into possession of a massive amount of gaseous and metal compounds that not only helped to give our galaxy its current shape, but as well gave it the ingredients to continue to grow.

“A ready supply of infalling gas during the merger ensured the maintenance of a disk-like configuration, with the thick disk continuing to form stars at a substantial rate,” the study states.

Scientists say that as they studied this galactic data, they discovered that stars formed prior to the Milky Way consuming Gaia–Enceladus have a redder color to them due to their metal content. Stars that were formed after this galactic event possess profiles that suggest they were made far more recently and under much different chemical conditions.

The study suggests, however, that while the different chemical makeup between stars helps to paint a better picture on how the Milky Way absorbed another galaxy, pinpointing a more specific timetable for when this event took place remains challenging. Having a more exact timeline would further help to illuminate the Milky Way’s intergalactic role in our cosmic history.

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