An artistic version of generic stellar currents in the Milky Way. Credit: NASA / JPL-Caltech / R. Hurt, SSC & Caltech
The study of Theia 456 found that nearly 500 stars were born simultaneously.
The Milky Way homes 8,292 recently discovered stellar currents – all called Theia. But Theia 456 is special.
A stellar stream is a rare linear pattern – rather than a group – of stars. After combining several data sets captured by the Gaia Space Telescope, a team of astrophysicists found that all 468 stars of Theia 456 were born at the same time and moving in the same direction across the sky.
“Most asterisks are formed together,” said Jeff Andrews, a North-West University astrophysicist and team member. ‘What’s exciting about Theia 456 is that it’s not a small bunch of stars together. It is long and elongated. There are relatively few streams that are close, young and so widely distributed. ”
Andrews presented this research during a virtual press briefing at the 237th meeting of the American Astronomical Society. “Theia 456: A New Stellar Association in the Galactic Disk” took place on 15 January 2021 as part of a session on ‘The Modern Milky Way’.
Andrews is a postdoctoral fellow at Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). He did this work with the astrophysicists Marcel Agüeros and Jason Curtis of Columbia University, Julio Chanamé of Pontifica Universidad Catolica, Simon Schuler of the University of Tampa and Kevin Covey and Marina Kounkel of West Washington University.
While researchers have long known that stars form in groups, most known clusters are spherical. Recently, astrophysicists have begun to find new patterns in the air. They believe that long strings of stars were once stiff clusters, gradually torn apart and stretched by tidal forces.
“As our instrumentation, our technology, and our ability to extract data began to become more advanced, we found that stars exist in more structures than clumps,” Andrews said. ‘They often form these currents over the air. Although we have known this for decades, we are beginning to find it hidden. ‘
Theia 456 is over 500 light years old and is one of the hidden streams. Because it lives within the Milky Way’s galactic plane, it can easily get lost in the background of 400 billion stars. Most stellar currents occur elsewhere in the universe – through telescopes that point away from the Milky Way.
“We tend to focus our telescopes in other directions because it’s easier to find things,” Andrews said. ‘Now we’re starting to find these currents in the galaxy itself. It’s like finding a needle in a haystack. Or, in this case, find a ripple in an ocean. ‘
The identification and investigation of these structures is a challenge in computer science. Artificial intelligence algorithms combed large sets of stellar data to find these structures. Subsequently, Andrews developed algorithms to cross-reference the data with existing catalogs of iron flux of documented stars.
Andrews and his team found that the 468 stars in Theia 456 had similar iron abundance, meaning that the stars – 100 million years ago – probably formed together. The researchers added further evidence to this finding and examined a data box for light curves that determines how stars’ brightness changes over time.
‘We are beginning to find these currents in the Milky Way system itself. It’s like finding a needle in a haystack. Or, in this case, find a ripple in an ocean ”- Jeff Andrews, astrophysicist
“It can be used to measure how fast the stars are spinning,” Agüeros said. “Stars of the same age should show a clear pattern in their rotation pattern.”
Using data from NASAAndrew’s and his colleagues’ Transiting Exoplanet Survey Satellite and from the Zwicky Transient Facility – both of which produced light curves for stars in Theia 456 – were able to determine that the stars in the stream have a common age.
The team also found that the stars were moving in the same direction together.
“If you know how the stars move, you can trace back to find where the stars came from,” Andrews said. ‘As we rolled the clock backwards, the stars got closer and closer to each other. So we think all these stars were born together and have a common origin. ”
Andrews said that the combination of data sets and data mining is essential for understanding the universe around us.
“You can only get that far with one data set,” he said. “If you combine datasets, you get a much richer idea of what’s in the air.”