468 stars in the Milky Way in one of the stellar streams were born simultaneously

The Milky Way contains 8,292 newly discovered stellar streams – all named Theia. But there is a special stellar stream – Theia 456. The fact is that 468 stars were born there at the same time! It is reported by Northwestern University.

The stellar stream is a rare linear structure, not a cluster of stars. After combining several datasets captured by the Gaia Space Telescope, the astrophysicist team found that all 468 stars in Theia 456 were born at the same time and move in the same direction across the sky.

“Most star clusters form together. Theia 456 is not a small group of stars put together. It is long and extended.”

Jeff Andrews, astrophysicist at Northwestern University

Although researchers have long known that stars form in groups, the most famous clusters are spherical. It is only recently that astrophysicists have begun to find new patterns in the sky. They believe that long chains of stars were once dense clusters, gradually being torn apart and stretched by tidal forces.

Theia 456, stretching over 500 light years, is one of those hidden streams. Since it is located in the galactic plane of the Milky Way, it is easily lost against the background of the 400 billion stars in the galaxy. Most stellar streams are found somewhere in the Universe – with telescopes pointed away from the Milky Way.

“We tend to focus our telescopes in a different direction because it’s easier to find objects that way. We are now starting to find these streams in the galaxy itself. It’s like finding a needle in a haystack. Or, in this case, find ripples in the ocean.”

Jeff Andrews, astrophysicist at Northwestern University

Identifying and studying these structures is the task of data science. Artificial intelligence algorithms have combed huge amounts of star data to find these structures. Andrews then developed algorithms to match this data with pre-existing catalogs of documented iron abundance in stars.

Andrews and his team found that 468 stars in Theia 456 have the same iron abundance, which means the stars probably formed together 100 million years ago. Adding additional evidence to this discovery, the researchers examined a dataset that captures how the brightness of stars changes over time.

“This can be used to measure the speed of rotation of stars. Stars of the same age should show a clear pattern in their rotational speed. If you know how the stars move, you can go back to find out where the stars came from. We think that all these stars were born together and have a common origin.”

Jeff Andrews, astrophysicist at Northwestern University

Using data from the NASA Transiting Exoplanet Survey Satellite and the Zwicky Transient Facility – both of which plotted curves for the stars on Theia 456 – Andrews and his colleagues were able to determine that the stars in the stream share a common age. The team also found that the stars move together in the same direction.

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Alexandr Ivanov earned his Licentiate Engineer in Systems and Computer Engineering from the Free International University of Moldova. Since 2013, Alexandr has been working as a freelance web programmer.
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Alexandr Ivanov

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