Astronomers Discover Milky Way Galaxy Grew from the Inside Out

Astronomers have made a breakthrough by using data from the Gaia-ESO project. They've found evidence backing up theoretically predicted divisions in the chemical composition of the stars that make up the Milky Way's disc, which suggests that stars in the inner regions of the Galactic dis were the first to form. This means that our galaxy grew from the inside-out.

In order to make this new discovery, the researchers used data from the 8-m Very Large Telescope (VLT) in Chile. They took detailed observations of stars with a wide range of ages and locations in the Galactic disc to accurately determine their "metallicity," which is the amount of chemical elements most stars are made from.

"The different chemical elements of which stars-and we-are made are created at different rates-some in massive stars which live fast and die young, and others in sun-like stars with more sedate multi-billion-year lifetimes," said Gerry Gilmore, one of the researchers, in a news release.

So what did they find? The scientists discovered that older, metal poor stars inside the solar circle are far more likely to have high levels of magnesium. The higher level of the element inside the solar circle suggests that the area contained more stars that lived fast and died young in the past.

The researchers also noted that the stars that lie in the outer regions of the Galactic disc are predominantly younger, both metal rich and metal poor and have surprisingly low magnesium levels. This, in particular, shows astronomers how our galaxy evolved.

"We have been able to shed new light on the timescale of chemical enrichment across the Milky Way disc, showing that outer regions of the disc take a much longer time to form," said Maria Bergemann, one of the researchers, in a news release. "This supports theoretical models for the formation of disc galaxies in the context of Cold Dark Matter cosmology, which predict that galaxy discs grow inside out."

The findings reveal a bit more about our galaxy. In addition, they may pave the way for future discoveries about other galaxies.

The findings are published in the journal Astronomy and Astrophysics.