Physics Reports
399 (2004) 1–70
www.elsevier.com/locate/physrep
The astrophysics of cool white dwarfs
BradHansen
Department of Physics and Astronomy, Institute of Geophysics and Planetary Physics,
University of California, Los Angeles, Los Angeles, CA 90025, USA
Accepted1 July 2004
editor: M.P. Kamionkowski
Available online 14 August 2004
Abstract
Old, cool white dwarfs convey valuable information about the early history of our Galaxy. They have been
used to determine the age of the Galactic disk, several open clusters and a globular cluster. We review the current
understandingofthephysicsofcoolwhitedwarfs,includingtheirmassdistribution,chemicalevolution,andcooling.
We also examine the role of white dwarfs as tracers of various stellar populations, both in terms of observational
searches andtheoretical models.
© 2004 Elsevier B.V. All rights reserved.
PACS: 97.10.Cv; 98.10.+z; 98.35.Ln; 97.82.−j
Keywords: White dwarfs; Stars: fundamental parameters; Stars: kinematics; Planetary systems; Galaxy: stellar content
Contents
1. Apology andintroduction .............................................................................. 3
2. The basics of white dwarf cooling ....................................................................... 3
3. Energy sources ....................................................................................... 5
3.1. Gravitational & thermal energy .................................................................... 5
3.2. Nuclear energy contributions ...................................................................... 6
3.3. Crystallisation .................................................................................. 7
3.3.1. Separation of C/O in mixedcores ........................................................... 7
E-mail address: hansen@astro.ucla.edu (B. Hansen).
0370-1573/$- see front matter © 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.physrep.2004.07.001