Astronomers have created a groundbreaking map detailing the life cycles of stars within the Milky Way's open clusters, utilizing data from the European Space Agency's Gaia mission. Researchers from EPFL and the Max Planck Institute for Astronomy have cataloged approximately 35,000 variable stars across 1,200 open clusters. This comprehensive study, published in Astronomy & Astrophysics, provides a dynamic view of stellar evolution, aging, and death within their stellar communities.
Open clusters, regions where stars form from the same material and remain gravitationally bound, serve as natural laboratories for astronomical study. Variable stars, whose brightness fluctuates, offer critical insights into stellar physics and the galactic environment. Previously, these areas of study were often pursued independently. This research, however, integrates both perspectives, revealing new patterns in stellar evolution that were previously hidden.
The findings indicate that variability is a common characteristic among stars, with at least one in five stars in these clusters exhibiting changes in brightness. A significant discovery is the link between a cluster's age and the types of variable stars it contains. Younger clusters host a diverse range of variable stars, reflecting various evolutionary stages, while older clusters tend to feature stars with more stable, sun-like cycles, suggesting a maturation into predictable rhythms.
Furthermore, the study highlights certain variable stars as valuable cosmic chronometers, capable of reliably indicating a cluster's age. This offers a more direct method for dating star groups compared to complex theoretical models. The researchers have made their extensive catalog of variable stars, including their positions, types, and characteristics, publicly available. This resource also provides the clearest depiction to date of how different variable star types are distributed on the Hertzsprung-Russell Diagram, a fundamental tool for tracking stellar evolution.
The Gaia mission, despite its recent deactivation, continues to yield invaluable data. Its vast archive remains a rich source for ongoing scientific discovery, underscoring humanity's enduring quest to comprehend its origins and place in the universe. As Richard I. Anderson, head of the Standard Candles and Distances Laboratory at EPFL, stated, "We are made of stardust. Understanding the lives of stars and the physics that govern stars is crucial to understanding our origins and place in the cosmos."