Astrophysics & Particle Physics-APPC 2026

White dwarfs are the small, dense end products of stars that have run out of nuclear fuel, usually made up of stars with original masses less than on the order of 8 solar masses. They are the ultimate evolutionary endpoint for most stars in the universe, including the Sun.A white dwarf is kept from collapsing under gravity by electron degeneracy pressure, a quantum mechanical phenomenon due to the Pauli exclusion principle.

Consequently, white dwarfs are very dense, having Sun-like masses but Earth-like volumes. The Chandrasekhar limit (~1.4 solar masses) is the upper mass a white dwarf can support before it collapses into a neutron star or undergoes a Type Ia supernova.White dwarfs slowly cool and disperse over billions of years, releasing leftover thermal energy. Their rates of cooling are a cosmic chronometer, enabling astronomers to make an estimate of the age of stellar populations within the Milky Way and globular clusters.

Many white dwarfs are members of binary systems, where mass transfer will give rise to events such as novae or Type Ia supernovae, which are significant standard candles for the measurement of cosmic distances. Measurements by optical, ultraviolet, and X-ray telescopes assist in ascertaining their temperature, mass, size, and chemical composition, providing insight into stellar evolution and final state of stars.White dwarfs also inform us about stellar interiors, nuclear burning histories, and chemical enrichment. Investigations of white dwarf populations constrain theories of galactic evolution, the initial mass function, and the compact stellar remnant distribution.White dwarfs are a pillar of contemporary astrophysics, connecting stellar life cycles with supernovae explosions, planetary system life cycles, and the chemical evolution of galaxies, and are therefore key objects for both observational and theoretical research in stellar and galactic astronomy.