Overview of the Near-IR S0 galaxy Survey (NIRS0S)
  A review of the results of the Near-IR S0 galaxy Survey (NIRS0S) is
presented. NIRS0S is a magnitude (mB 12.5 mag) and inclination (< 65o) limited
sample of 200 nearby galaxies, mainly S0s. It uses deep Ks -band images,
typically reaching a surface brightness of 23.5 mag arcsec^(-2) . Detailed
visual and photometric classifications were made, for the first time coding
also the lenses in a systematic manner. As a comparison sample, a similar sized
spiral galaxy sample with similar image quality was used. The main emphasis
were to study whether the S0s are former spirals in which star formation has
been ceased, and also, how robust are bars in galaxies. Based on our analysis
the Hubble sequence was revisited: following the early idea by van den Bergh we
suggested that the S0s are spread throughout the Hubble sequence in parallel
tuning forks as spirals (S0a, S0b, S0c etc.). This is evidenced by our improved
bulge-to-total (B/T) flux ratios, reaching as small values as typically found
in late-type spirals. The properties of bulges and disks in S0s were found to
be similar to those in spirals. Also, the masses and scale parameters of the
bulges and disks were found to be coupled. Bars were found to be fairly robust
both in S0s and spirals, but inspite of that bars might evolve significantly
within the Hubble sequence.
