True age of the Milky Way

(ORDO NEWS) — Astronomers from the Max Planck Institute for Astronomy in Heidelberg (Germany) have come close to unraveling the true age of the Milky Way.

As part of the Gaia ESA mission, they examined the thick disk of the galaxy and concluded that it began to form two billion years earlier than previously thought. The results of the study are described in the journal Nature.

In the course of the analysis, scientists found that the thick disk of the Milky Way began to form about 13 billion years ago, although they previously called the age about 11 billion years.

Thus, the galaxy in which the solar system is located appeared only 0.8 billion years after the Big Bang.

Experts came to such conclusions by examining the brightness and positions of stars from the Gaia Early Data Release 3 (EDR3) database and combining this information with the data on the chemical composition of 250 thousand stars, which were obtained from the Chinese Large Multi-purpose Spectroscope for Observing Vast Sky Regions (LAMOST), to determine their age.

The collected information revealed that the formation of the Milky Way was divided into two phases. In the first, which began less than a billion years after the Big Bang, the first stars began to appear in a thick disk.

The inner part of the halo, astronomers suggest, also began to form at this stage, but a significant part was formed about two billion years later, after merging with the dwarf galaxy Gaia-Sausage-Enceladus.

It was this process that filled most of the halo with stars. The thin disk containing the Sun was already formed during the second phase.

The researchers believe that their observations will be useful for studying other galaxies like the Milky Way.

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