Not to be confused with the Chandrasekhar limit.
During the main sequence stage, a star burns the hydrogen in its core and transforms it into helium. When the helium mass amounts to about 10% of the initial stellar mass, the star can no longer maintain the hydrostatic equilibrium in its core; the star increases its volume and leaves the main sequence in order to become a red giant.
Schoenberg-Chandrasekhar limit
Chandrasekhar-Schonberg limit
Schönberg-Chandrasekhar limit
Schonberg-Chandrasekhar limit
Stellar evolution
Gravitational collapse