What is the Chandrasekhar limit?

The Chandrasekhar limit is the maximum mass that a white dwarf star can have.

White dwarf stars are the remnants of low-mass stars that have exhausted their nuclear fuel and collapsed. They are incredibly dense, with a mass comparable to that of the Sun but a radius only about the size of the Earth. The pressure that supports a white dwarf against gravitational collapse comes from the electron degeneracy pressure, which arises from the exclusion principle that prevents two electrons from occupying the same quantum state.

As a white dwarf gains mass, its density increases and the electrons become more tightly packed. Eventually, the electron degeneracy pressure is no longer sufficient to support the star against gravity, and it collapses. This collapse can trigger a runaway nuclear fusion reaction that results in a Type Ia supernova.

The Chandrasekhar limit is the maximum mass that a white dwarf can have before it collapses. It is named after Subrahmanyan Chandrasekhar, who first calculated the limit in 1930. The limit is approximately 1.4 times the mass of the Sun, or about 2.7 x 10^30 kg. Any white dwarf that exceeds this mass will inevitably collapse and explode as a Type Ia supernova. This makes Type Ia supernovae valuable tools for measuring distances in astronomy, as they have a consistent luminosity and can be used as standard candles.