  We present the results of an analysis of Pan-STARRS1 Medium Deep Survey
multi-band (g,r,i,z,y) images of a sample of 698 low-redshift disk galaxies
that span broad ranges in stellar mass, star-formation rate, and bulge/disk
ratio. We use population synthesis SED fitting techniques to explore the radial
distribution of the light, color, surface mass density, mass/light ratio, and
age of the stellar populations. We characterize the structure and stellar
content of the galaxy disks out to radii of about twice Petrosian r90, beyond
which the halo light becomes significant. We measure normalized radial profiles
for sub-samples of galaxies in three bins each of stellar mass and
concentration. We also fit radial profiles to each galaxy. The majority of
galaxies have down-bending radial surface brightness profiles in the bluer
bands with a break radius at roughly r90. However, they typically show single
unbroken exponentials in the reddest bands and in the stellar surface mass
density. We find that the mass/light ratio and stellar age radial profiles have
a characteristic "U-shape". There is a good correlation between the amplitude
of the down-bend in the surface brightness profile and the rate of the increase
in the M/L ratio in the outer disk. As we move from late- to early-type
galaxies, the amplitude of the down-bend and the radial gradient in M/L both
decrease. Our results imply a combination of stellar radial migration and
suppression of recent star formation can account for the stellar populations of
the outer disk.
