His work focused on:

* White Dwarf Stars: Chandrasekhar derived the Chandrasekhar limit, which determines the maximum mass a white dwarf star can have before collapsing under its own gravity.

* Stellar Evolution: He made significant contributions to understanding how stars evolve, including their structure, stability, and eventual fate.

While other scientists have made notable contributions to the study of stellar evolution, Chandrasekhar's work is considered groundbreaking and fundamental to the field.