Around 400 sibling star clusters found in Milky Way
What's the story
A team of astronomers from the Chinese Academy of Sciences has made a significant discovery in our galaxy. They have identified pairs of open clusters, or 'sibling' star groups, in the Milky Way. The study was led by PhD candidate Liu Guimei and her supervisor Prof. Zhang Yu from the Xinjiang Astronomical Observatory (XAO). Their findings were published in Astronomy & Astrophysics journal.
Cluster significance
Binary clusters: A key to understanding star formation
Stars are born in clusters, which can also form in pairs or groups. These pairs of open clusters are known as binary clusters (BCs). Their formation provides insights into how stars form within giant molecular clouds. This makes them crucial for studying star formation and cluster evolution. The recent study by Liu and her team used data from the Gaia satellite to identify these BCs systematically.
Findings
Study reveals 400 candidate binary clusters
The researchers examined almost 4,000 high-quality open clusters using Gaia DR3 astrometry and kinematics. They developed a statistical and quantitative criterion for spatial and velocity proximity, validating it against randomized mock samples. Using this framework, they identified 400 BC candidates and classified them into three categories: primordial binary clusters (co-natal), tidal-capture/resonant-capture binary clusters, and optical pairs (chance alignments).
Cluster interactions
Majority of candidate BCs show significant tidal interactions
Further analysis revealed that 61% of the candidate binary clusters are highly consistent in age and kinematics, suggesting they formed from the same giant molecular cloud. A whopping 83% show significant tidal interactions. The strength of these interactions is directly related to their spatial separation, the closer the pair, the stronger their mutual attraction and perturbation.
Research impact
Study provides a unified scheme for identifying BCs
The study offers a unified and clearly structured scheme for identifying and classifying galactic binary clusters. It suggests that hierarchical star formation could be an important channel of star formation. The research also offers key observational evidence for the formation mechanisms and dynamical evolution of multi-cluster systems, supporting a hierarchical and clustered scenario of star formation across multiple scales.