Home / Topics / Gravitation & Orbits
Neutron stars and white dwarfs
Advanced
Compact stellar remnants supported by degeneracy pressure.
White dwarfs (up to 1.4 M☉) are supported by electron degeneracy pressure; neutron stars by neutron degeneracy and nuclear forces, about 20 km across with density 10¹⁷ kg/m³.
A teaspoon of neutron star is about 10⁹ tonnes.
Beyond ~2–3 M☉ collapse to a black hole.
In more detail
White dwarfs are supported by electron degeneracy pressure, and neutron stars by neutron degeneracy pressure. Stars above a critical mass collapse into black holes.
Real-world uses
- Neutron stars are observed as pulsars, rotating beams of radiation.
- White dwarfs are studied to understand the final fate of Sun-like stars.
- Astronomers study white dwarfs and neutron stars to learn how matter behaves at extreme densities.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
What is degeneracy pressure?
A quantum effect that resists compression, independent of temperature.
How dense is a neutron star?
About the density of an atomic nucleus, several hundred million tonnes per cubic centimetre.
What holds a white dwarf up against gravity?
Electron degeneracy pressure, which resists compression even when the star is not hot.
Related topics in Gravitation & Orbits
Gravitational waves · Black holes · Schwarzschild radius · Dark matter evidence · Newton's shell theorem · Gravitational self-energy