Astronomers Conclude That a Huge Portion of the Milky Way Is Much Older Than Expected

Astronomers Conclude That a Huge Portion of the Milky Way Is Much Older Than Expected

We all live in a pretty big galaxy, considering that its diameter reaches 100,000 light-years across. Therefore, it’s safe to assume that astronomers might have some difficulties when it comes to understanding everything there is to know about the Milky Way.

The European Space Agency launched the Gaia mission almost a decade ago, and it’s expected to continue its operation until 2025. Unsurprisingly, it already contributes to uncovering information that many weren’t expecting. 

Milky Way’s “thick disc” began forming roughly 2 billion years earlier

Maosheng Xiang and Hans-Walter Rix, both from the Max-Planck Institute for Astronomy from Heidelberg (Germany), analyzed data from the Gaia mission. Thus, they concluded, according to, that the part of the “thick disc” of our Milky Way galaxy began its formation about two billion years earlier than scientists expected. That means that the structure began to form 13 billion years ago.

Maosheng explained as quotes:

Since the discovery of the ancient merger with Gaia-Sausage-Enceladus, in 2018, astronomers have suspected that the Milky Way was already there before the halo formed, but we didn’t have a clear picture of what that Milky Way looked like. Our results provide exquisite details about that part of the Milky Way, such as its birthday, its star-formation rate and metal enrichment history. Putting together these discoveries using Gaia data is revolutionizing our picture of when and how our galaxy was formed.

In the case of subgiant stars, the energy that should normally be in their cores has been moved into the exterior. The subgiant phase itself allows its age to be determined due to its short evolutionary phase.

Timo Prusti, a Gaia Project Scientist at ESA, declared as the same source mentioned above quotes:

With each new analysis and data release, Gaia allows us to piece together the history of our galaxy in even more unprecedented detail. With the release of Gaia DR3 in June, astronomers will be able to enrich the story with even more details.

Cristian Antonescu

Even since he was a child, Cristian was staring curiously at the stars, wondering about the Universe and our place in it. Today he's seeing his dream come true by writing about the latest news in astronomy. Cristian is also glad to be covering health and other science topics, having significant experience in writing about such fields.

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