Which of the following best describes why a white dwarf cannot have a mass greater than the 1.4 solar mass limit? A. White dwarf
s get hotter with increasing mass, and above the 1.4-solar-mass limit they would be so hot that even their electrons would melt. B. The upper limit to a white dwarf's mass is something we have learned from observations, but no one knows why this limit exists.
C. Electron degeneracy pressure depends on the speeds of electrons, which approach the speed of light as a white dwarf's mass approaches the 1.4-solar-mass limit.
D. White dwarfs are made only from stars that have masses less than the 1.4-solar-mass limit.
Answer: C. Electron degeneracy pressure depends on the speeds of electrons, which approach the speed of light as a white dwarf's mass approaches the 1.4-solar-mass limit.
