  We analyze the asymptotic behavior of linear Fokker-Planck equations with
time-dependent coefficients. Relaxation towards a Maxwellian distribution with
time-dependent temperature is shown under explicitly computable conditions. We
apply this result to the study of Brownian motion in granular gases as
introduced J. J. Brey, J. Dufty and A. Santos (1999), by showing that the
Homogenous Cooling State attracts any solution at an algebraic rate.
