  Nuclear Stellar Disks (NSDs), of a few tens to hundreds of parsec across, are
a common and yet poorly studied feature of early-type galaxies. Still, such
small disks represent a powerful tool to constrain the assembling history of
galaxies, since they can be used to trace to the epoch when galaxies
experienced their last major merger event. By studying the fraction and stellar
age of NSDs it is thus possible to test the predictions for the assembly
history of early-type galaxies according the current hierarchical paradigm for
galaxy formation. In this paper we have produced the most comprehensive census
of NSDs in nearby early-type galaxies by searching for such disks in objects
within 100 Mpc and by using archival images from the Hubble Space Telescope. We
found that NSDs are present in approximately 20% of early-type galaxies, and
that the fraction of galaxies with NSDs does not depend on their Hubble type
nor on their galactic environment, whereas the incidence of NSDs appears to
decline in the most massive systems. Furthermore, we have separated the light
contribution of twelve such disks from that of their surrounding stellar bulge
in order to extract their physical properties. This doubles the number of
decomposed NSDs and although the derived values for their central surface
brightness and scale-length are consistent with previous studies they also give
a hint of possible different characteristics due to different formation
scenario between nuclear disks and other kinds of large galactic disks.
