Scientists at the Leibniz Institute for Astrophysics Potsdam (AIP) and Boston University have made a significant breakthrough in determining the ages of stars. They have successfully linked the rotation rates of stars in star clusters to those of field stars (stars outside clusters). This development allows them to estimate the ages of individual stars with a method called gyrochronology.
Gyrochronology relies on the relationship between a star’s rotation, color, and age. By observing a star’s brightness and measuring the rotation period based on the appearance of dark spots on its surface, researchers can estimate its age. Previous gyrochronology methods focused on stars within clusters, which share a common origin and age, making age determination relatively straightforward.
The recent study extended gyrochronology to field stars using a sample of over 300 wide binary stars. These binary stars consist of two stars orbiting each other from a distance, without disrupting their rotational evolution. Since wide binary stars are assumed to be of the same age due to their common origin, researchers tested if the gyrochronology method would hold true for them.
Surprisingly, the binary stars aligned perfectly with the cluster-based rotational evolution diagram. They could be grouped into subgroups associated with clusters of specific ages. Even binary stars with different masses exhibited remarkable consistency in their positions on the diagram, almost indistinguishable from actual clusters.
The stars located above the cluster ribs were presumed to be older than the measured clusters. The study also revealed that the rotational ages of both components of wide binary systems were consistent with each other. This diverse sample of binary stars across the sky, with varying stellar properties, suggested that gyrochronology is likely reliable for field stars.
Dr. Sydney Barnes, head of the Stellar Activity group at AIP, expressed confidence that this breakthrough would allow obtaining reliable ages for numerous field stars in the future. The findings hold significance for the PLATO satellite mission, enabling the discovery of planet-hosting stars and providing insights into the evolutionary history of exoplanets.