White dwarfs

Definition

White dwarfs are dense, compact remnants of low to medium-mass stars that have exhausted their nuclear fuel and expelled their outer layers. They are roughly the size of Earth but contain a mass comparable to that of the Sun.

5 Must Know Facts For Your Next Test

1. White dwarfs are found in the lower-left corner of the Hertzsprung-Russell (H–R) diagram.
2. They no longer undergo fusion reactions and instead cool over time by radiating away their residual heat.
3. A typical white dwarf has a mass up to 1.4 times that of the Sun, known as the Chandrasekhar limit.
4. The surface gravity on a white dwarf is extremely high due to its compactness, often exceeding 100,000 times that of Earth's gravity.
5. White dwarfs can eventually become black dwarfs after cooling for billions of years, although none have reached this stage yet since the universe is not old enough.

Review Questions

• Where are white dwarfs located on the H–R diagram?
• What process do white dwarfs use to generate energy?
• What is the significance of the Chandrasekhar limit concerning white dwarfs?

Related terms

Hertzsprung-Russell Diagram: A plot showing the relationship between stars' luminosities and their surface temperatures.

Chandrasekhar Limit: The maximum mass (approximately 1.4 solar masses) that a stable white dwarf star can have before collapsing into a neutron star or black hole.

Black Dwarf: A theoretical stellar remnant formed when a white dwarf has cooled sufficiently to no longer emit significant heat or light.