Newly Discovered Stars Reveal The Fascinating Evolution Of The Milky Way

Hubble's infrared view of the dusty heart of our Milky Way. NASA, ESA, and Hubble Heritage Team (STScI/AURA, Acknowledgment: T. Do, A.Ghez (UCLA), V. Bajaj (STScI)

An international team of astronomers has discovered a large population of special stars in the center of the Milky Way, which provides very interesting clues about how our galaxy evolved during its infancy.

The scientists used a sophisticated infrared survey, called the Apache Point Observatory Galactic Evolution Experiment (APOGEE), of hundreds of thousands of stars in the Milky Way and discovered some chemical tags on certain stars orbiting the core of our galaxy. These newly discovered stars look like they belong to globular clusters, tightly bound collections of stars.

These globular clusters are usually found outside the galactic disk, at over 100,000 light-years from the core, so how did these stars end up at the center of the Milky Way?

The astronomers believe that there were 10 times more globular clusters when the Milky Way was forming and these clusters came crashing down on the galaxies, with their stars dispersing around the galactic nucleus. The discovery is reported in the Monthly Notices of the Royal Astronomical Society.  

“This is a very exciting finding that helps us address fascinating questions such as what is the nature of the stars in the inner regions of the Milky Way, how globular clusters formed and what role they played in the formation of the early Milky Way – and by extension the formation of other galaxies,” lead author Ricardo Schiavon, from Liverpool John Moores University, said in a statement.

There are several unsolved problems related to the formation of globular clusters and galaxies, but this research provides some interesting clues. The core of the Milky Way has been difficult to study due to the intervening dust between here and there, but improvements in our infrared telescopes are allowing a deeper look towards the region.

These observations expand on previous research indicating the presence of globular cluster stars in the core.

“From our observations, we could determine the chemical compositions of thousands of stars, among which we spotted a considerable number of stars that differed from the bulk of the stars in the inner regions of the galaxy, due to their very high abundance of nitrogen,” Schiavon added in the statement.

“While not certain, we suspect that these stars resulted from globular cluster destruction. They could also be the byproducts of the first episodes of star formation taking place at the beginning of the galaxy’s history. We are conducting further observations to test these hypotheses.”

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