Astronomers have discovered 8,292 stellar currents in our galaxy. Instead of star clusters, currents form linear patterns.
Each stream is named after Theia by the Greek titan goddess of sight and celestial light.
When astronomers used the data collected by the European Space Agency The Gaia Space Telescope, to study Theia 456, discovered that the 468 stars in this current were born simultaneously. This elongated stream of stars also moves in the same direction together across the sky.
The discovery was presented Friday at the 237th meeting of the American Astronomical Society, which is occurring largely due to the pandemic.
“Most star clusters form together,” study author Jeff Andrews, a postdoctoral fellow at Northwestern University, said in a statement. “What’s exciting about Theia 456 is that it’s not a small group of stars together. It’s long and extended. There are relatively few currents nearby, young and so scattered.”
Stars often form in spherical groups, which are known as clusters. More recent data, however, have revealed other patterns, such as these long currents, that astronomers believe occurred when star clusters separated or stretched.
“As we have begun to be more advanced in our instrumentation, our technology, and our ability to extract data, we have discovered that stars exist in more structures than groups,” Andrews said. “They often form these currents across the sky. Even though we’ve known about them for decades, we’re starting to find some hidden ones.”
Theia 456 extends for 570 light years across the Milky Way.
This stellar current remained hidden by astronomers for a long time because it lives in the galactic plane, where the current can be easily enveloped by the 400 billion stars in the Milky Way. The galactic plane is where most of the mass of a galaxy exists.
Normally, stellar currents have been found outside our galaxy using telescopes pointing at 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 those currents in the galaxy itself. It’s like finding a needle in a haystack. Or, in this case, finding a ripple in an ocean.”
The stars of Theia 456 have a similar composition as they all contain approximately the same amount of iron. This suggests that the stars probably formed together about 100 million years ago.
Astronomers also examined how the brightness of these stars has changed over time and determined that the stars rotate at similar rates. This is one more proof that they are the same age.
“If you know how the stars move, you can go back to find out where the stars came from,” Andrews said. “As we turned the clock back, the stars got closer and closer. So we believe that all of these stars were born together and have a common origin.”
Finding out more about star formation in galaxies could lead to a greater understanding of the universe and how it was filled with galaxies and stars.