In a cosmic breakthrough, astronomers have stitched together a massive star map that reveals how stars live, age, and die, not in isolation, but as part of their celestial communities.
Stars don’t always shine steadily. Some pulse, flicker, and flare; these are called variable stars, and their changing brightness holds clues about the inner workings of stars and the galaxy itself. Meanwhile, open clusters, groups of stars born together from the same cloud, act like natural laboratories, showing how stars evolve side by side.
Until now, scientists studied clusters and variable stars separately, like reading two chapters of a book without realizing they’re part of the same story. But researchers Richard I. Anderson (EPFL) and Emily Hunt (Max Planck Institute) just flipped the script.
Using data from the European Space Agency’s Gaia mission, the team mapped nearly 35,000 variable stars across 1,200 open clusters in the Milky Way. That’s like zooming out to see the entire starry neighborhood in motion.
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Their findings, published in Astronomy & Astrophysics, reveal striking new patterns in how stars evolve. About one in five stars within open clusters regularly change their brightness, offering a dynamic glimpse into stellar behavior. Young clusters are bustling with a diverse mix of variable stars, each flickering in its way, while older clusters tend to settle into calmer, more predictable cycles, similar to our Sun’s slow rhythm.
Perhaps most exciting, the researchers discovered that certain types of variable stars can act as natural age markers, allowing scientists to estimate the age of star clusters without relying on complex models.
The team didn’t just keep this treasure to themselves; they released a public catalog of all 35,000 variable stars, including their positions, types, and properties. They also created the clearest diagram yet of how these stars fit into the Hertzsprung-Russell Diagram, the key chart astronomers use to track stellar evolution.
Though the Gaia satellite has been switched off, its data, covering nearly 2 billion stars, is just beginning to shine. Anderson calls this study a “teaser” for what’s coming in future data releases, which promise to revolutionize how we understand star populations through their light.
“We are made of stardust,” Anderson reminds us. “By understanding how stars live and change, we get closer to understanding where we come from, and where we’re going.”
Journal Reference
- Richard I. Anderson and Emily Hunt. A bird’s eye view of stellar evolution through populations of variable stars in Galactic open clusters. Astronomy & Astrophysics. DOI: 10.1051/0004-6361/202555111