Astronomy 1021 Lecture Notes - Lecture 16: Crab Nebula, Supernova Remnant, White Dwarf

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Sarah Gallagher

Document Summary

White dwarfs are the remaining cores of dead, low-mass stars. White dwarfs cool off and grow dimmer with time. White dwarfs with the same mass as the sun are about the same size as earth. Quantum mechanics says that electrons must move faster as they are squeezed into a very small space. As a white dwarf"s mass approaches 1. 4msun its electrons must move at nearly the speed of light. Because nothing can move faster than light, a white dwarf cannot be more massive than 1. 4m sun the white dwarf limit. As white dwarfs get more massive, they shrink. Electron degeneracy will only provide enough pressure to balance gravity up to about 1. 4msun. Then, velocities that electrons must have become greater than the speed of light not possible. A stellar remnant >1. 4msun becomes a neutron star. Gravity squeezes the electrons and protons together into neutrins. A neutron star is as dense as an atomic nucleus.