Astrophysics & Particle Physics-APPC 2026

Star Clusters are stellar clusters held in common by gravity, having a shared birth place, and usually the same ages and chemical makeup. They provide natural laboratories to experiment with stellar evolution, star formation, and galactic structure. The two broad categories of star clusters are open clusters and globular clusters. Open clusters are young, poorly bound clusters of tens to thousands of stars located mostly in the disk of the galaxy. They tend to harbor luminous, large stars and are important for understanding early stellar evolution. Globular clusters, by contrast, are tightly packed, older clusters filled with hundreds of thousands of stars, mostly located in the galactic halo. They give us clues about early galaxy formation and the evolution of ancient stellar populations.Astronomers use photometry, spectroscopy, and astrometry to measure the ages, compositions, masses, and kinematics of stars in observations of star clusters. Hertzsprung-Russell diagrams of clusters enable astronomers to map the life stages of planets and stellar models to calibrate.

Kinematics of clusters inform astronomers regarding mass distribution, tidal interactions, and the lifetimes of clusters.Star clusters also contribute to understanding the dynamics of stars, such as planets interacting with each other in binaries, stellar collisions, and mass segregation, affecting the long-term development of clusters. Moreover, extragalactic star clusters assist in exploring galaxy formation and evolution in other galaxies. By examining star clusters, astronomers are able to understand star formation mechanisms, chemical enrichment, stellar evolution, and the structure and history of galaxies.

They also serve to sharpen models of stellar populations and dynamics, bridging from the individual stars to the larger picture of galactic evolution.Star Clusters are basic astrophysical systems, providing an insight into the life histories of stars, stellar population evolution, and the galaxy formation history throughout the cosmos.