Astronomers have discovered 8,292 stellar currents in our galaxy. Instead of star clusters, currents form linear patterns.
Each stream is called Theia for the Greek titan goddess and celestial light.
When astronomers used data collected by the European Space Agency Using the Gaia Space Telescope to study Theia 456, they discovered that all 468 stars in this stream were born simultaneously. These elongated stream of stars also move together in the same direction across the sky.
The discovery was presented Friday at the 237th meeting of the American Astronomical Society, which is taking place virtually due to the pandemic.
“Most star clusters are formed 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 bunch of stars together. It’s long and elongated. There are relatively few streams that are close, young and so widely distributed.”
Stars are often formed in spherical groups, known as clusters. More recent data, however, have revealed other patterns, such as these long currents, which, according to astronomers, occurred when star clusters were torn apart or stretched.
“As we began to become more advanced in our instrumentation, our technology and our ability to extract data, we found that stars exist in more structures than clumps,” Andrews said. “They often form these currents over the sky. Although we have known this for decades, we are beginning to find hidden currents.”
Theia 456 stretches over 570 light-years across the Milky Way.
This stellar stream has long been hidden from astronomers because it lives in the galactic plane, where the current can be easily enveloped by the Milky Way’s 400 billion stars. The galactic plane is where most of the mass of a galaxy exists.
Usually star currents are found outside our galaxy by telescopes pointing out of 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, finding a ripple in an ocean.”
The stars in Theia 456 have a similar composition in that they all contain about the same amount of iron. This suggests that the stars probably formed together about 100 million years ago.
Astronomers also looked at how the brightness of these stars changed over time and determined that the stars rotate at the same rate. This is further proof that they are the same age.
“If you know how the stars move, you can trace back to where the stars came from,” Andrews said. “As we rolled the clock backwards, the stars became closer and closer to each other. We think all these stars were born together and have a common origin.”
The discovery of more about star formation in galaxies could lead to a greater understanding of the universe and how it is filled with galaxies and stars.