Why is there an upper limit to the mass of a white dwarf?
A) White dwarfs come only from stars with masses less than 1.4 solar masses.
B) The more massive the white dwarf, the greater the degeneracy pressure and the faster the speeds of its electrons. Near 1.4 solar masses, the speeds of the electrons approach the speed of light, and no more mass can be supported.
C) The more massive the white dwarf, the higher its temperature and hence the greater its degeneracy pressure. Near 1.4 solar masses, the temperature becomes so high that all matter effectively melts into subatomic particles.
D) The upper limit to the masses of white dwarfs was determined through observations of white dwarfs in binary systems, but no one knows why the limit exists.

Question

Quizplus · Accepted Answer

The more massive the white dwarf, the greater the degeneracy pressure, which arises from the exclusion principle preventing electrons from occupying the same energy state. As the mass of the white dwarf approaches 1.4 solar masses, the speeds of the electrons approach the speed of light, and the degeneracy pressure cannot counteract the gravitational force. This is known as the Chandrasekhar limit and sets an upper limit to the mass of a white dwarf.

Why Is There an Upper Limit to the Mass of a White