Do Disk Galaxies with Abnormally Low Mass-to-Light Ratios Exist?
  We performed the photometric B, V and R observations of nine disk galaxies
that were suspected in having abnormally low total mass-to-light (M/L) ratios
for their observed color indices. We use our surface photometry data to analyze
the possible reasons for the anomalous M/L. We infer that in most cases this is
a result of errors in photometry or rotational velocity, however for some
galaxies we cannot exclude the real peculiarities of the galactic stellar
population. The comparison of the photometric and dynamical mass estimates in
the disk shows that the low M/L values for a given color of disks are probably
real for a few our galaxies: NGC 4826 (Sab), NGC 5347 (Sab), and NGC 6814 (Sb).
The small number of such galaxies suggests that the stellar initial mass
function is indeed universal, and that only a small fraction of galaxies may
have a non-typical low-mass star depleted initial mass function. Such galaxies
require more careful studies for understanding their star formation history.
