Fr.: temps de refroidissement
1) The time in which a → white dwarf cools to half its
temperature. It depends on the composition, the mass, and the actual luminosity
at some point in time. Cooling time is given by the relation:
t = 8.8 × 106 (12/A) (M)5/7 (μ/2)-2/7
(L)-5/7 in years, where M and L are mass and luminosity in
solar units, A the mean → atomic mass, and μ the
→ mean molecular weight (Iben & Tutukov, 1984, ApJ 282, 615).
See also → Mestel theory;
→ white dwarf crystallization.