White dwarf

Definition

A white dwarf is the remnant of a low to medium mass star that has exhausted its nuclear fuel and shed its outer layers. It is incredibly dense, with a mass comparable to the Sun but a volume similar to Earth.

5 Must Know Facts For Your Next Test

1. White dwarfs are found in the lower left region of the H–R Diagram, indicating high temperature but low luminosity.
2. They are supported against gravitational collapse by electron degeneracy pressure.
3. A typical white dwarf has a surface temperature between 8,000 and 40,000 K.
4. Over time, white dwarfs cool down and fade away into black dwarfs, although no black dwarfs exist yet due to the age of the universe.
5. In binary star systems, if a white dwarf accumulates enough material from its companion star, it can undergo a Type Ia supernova.

Review Questions

Related terms

H–R Diagram: A graph plotting stars by their absolute magnitude or luminosity versus their surface temperature or spectral class.

Electron Degeneracy Pressure:

The quantum mechanical pressure arising from the Pauli exclusion principle that supports white dwarfs against gravitational collapse.

Type Ia Supernova:

An explosive event occurring when a white dwarf in a binary system accumulates enough mass to surpass the Chandrasekhar limit.