Stellar Disc Truncations and Extended Haloes in Face-on Spiral Galaxies
  We use data from the IAC Stripe82 Legacy Project to study the surface
photometry of 22 nearby, face-on to moderately inclined spiral galaxies. The
reprocessed and combined Stripe 82 $g'$, $r'$ and $i'$ images allow us to probe
the galaxy down to 29-30 $r'$-magnitudes/arcsec$^2$ and thus reach into the
very faint outskirts of the galaxies. Truncations are found in three galaxies.
An additional 15 galaxies are found to have an apparent extended stellar halo.
Simulations show that the scattering of light from the inner galaxy by the
Point Spread Function (PSF) can produce faint structures resembling haloes, but
this effect is insufficient to fully explain the observed haloes. The presence
of these haloes and of truncations is mutually exclusive, and we argue that the
presence of a stellar halo and/or light scattered by the PSF can hide
truncations. Furthermore, we find that the onset of the stellar halo and the
truncations scales tightly with galaxy size. Interestingly, the fraction of
light does not correlate with dynamic mass. Nineteen galaxies are found to have
breaks in their profiles, the radius of which also correlates with galaxy size.
