Astronomers have discovered 8,292 stellar flows in our galaxy. Instead of clusters of stars, linear patterns form.
Each stream is called Theia, after the Greek titan goddess of sight and heavenly light.
When astronomers used data collected by the European Space Agency Gaia space telescope to study Theia 456, they found that all 468 stars in this stream were born at the same time. This elongated stream of stars also moves together in the same direction through the air.
The discovery was presented Friday at the 237th meeting of the American Astronomical Society, which is virtually taking place as a result of the pandemic.
“Most star clusters are formed together,” study author Jeff Andrews, a postdoctoral researcher at Northwestern University, said in a statement. “The exciting thing about Theia 456 is that it is not a small group of stars together. It is long and expansive. There are relatively few streams around, young and so widely spread.”
Stars are often formed in spherical groups known as clusters. More recent data, however, has revealed other patterns, such as these long currents that astronomers believe occurred when clusters of stars were torn apart or stretched out.
“As we’ve advanced in our tools, our technology, and our ability to mine data, we’ve discovered that stars exist in more structures than clumps,” Andrews said. “They often form these streams through the sky. Although we’ve known about them for decades, we’re starting to find hidden.”
Theia 456 spans the Milky Way for 570 light years.
This stellar flow has long been hidden from astronomers because it lives in the galactic plane, where the flow can be easily obscured by the Milky Way’s 400 billion stars. The galactic plane is where most of the mass of a galaxy exists.
Typically, star streams outside our galaxy have been found by telescopes pointing away from the Milky Way.
“We tend to point our telescopes in different directions because it’s easier to find things,” Andrews said. Now we are starting to find these 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 in Theia 456 have a similar composition because they all contain about the same amount of iron. This suggests that the stars probably all formed together about 100 million years ago.
Astronomers also looked at how the brightness of these stars has changed over time and found that the stars orbit at similar speeds. This is further proof that they are the same age.
“If you know how the stars move, you can go back and see where the stars came from,” Andrews said. “As we turned the clock backwards, the stars got closer and closer. So we think all these stars were born together and have a common origin.”
More information about star formation in galaxies could lead to a better understanding of the universe and how it was filled with galaxies and stars.