  An increasing number of white dwarf stars show atmospheric chemical
composition polluted by heavy elements accreted from debris disk material. The
existence of such debris disks strongly suggests the presence of one or more
planet(s) whose gravitational interaction with rocky planetesimals is
responsible for their disruption by tidal effect. The ZZ Ceti pulsator and
polluted DAZ white dwarf GD 133 is a good candidate for searching for such a
potential planet. We started in 2011 a photometric follow-up of its pulsations.
As a result of this work in progress, we used the data gathered from 2011 to
2015 to make an asteroseismological analysis of GD 133, providing the star
parameters from a best fit model with $M$/$M_{\odot}$ = 0.630 $\pm$ 0.002,
$T_{\rm eff}$ = 12400 K $\pm$ 70 K, log($M_{\rm He}/M$) = -2.00 $\pm$ 0.02,
log($M_{\rm H}/M$) = -4.50 $\pm$ 0.02 and determining a rotation period of
$\approx$ 7 days.
