Question

Describe the mass, radius, and thus density of a typical white dwarf star. How does this compare to the density of water? What kind of pressure is used by a white dwarf to oppose its strong gravity? How does a white dwarf’s radius depend on its mass, and how does this set the maximum mass of a white dwarf?

The mass of white-dwarf has a limiting mass of 1.4 solar masses (Chandrashekar limit) with radius in the order of about 2% of solar radius. The density of the star is in order of 10^5 to 10^7 kg/m^3. This is around 2-4 orders of higher magnitude as compared to water. The electron degeneracy pressure is used to oppose the strong gravity, It is caused due to the result of Paulli's exclusion principle. The radius is inversely proportional to cube root of mass.

The chandrashekar limit gives the maximum mass of white dwarf as 1.4 solar masses.

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