Photometric scaling relations of lenticular and spiral galaxies
  Photometric scaling relations are studied for S0 galaxies and compared with
those for spirals. New 2D K_s-band multi-component decompositions are presented
for 122 early-type disk galaxies. Combining with our previous decompositions,
the final sample consists of 175 galaxies. As a comparison sample we use the
Ohio State University Bright Spiral Galaxy Survey (OSUBSGS), for which similar
decompositions have previously been made by us. Our main results are: (1)
Important scaling relations are present, indicating that the formative
processes of bulges and disks in S0s are coupled like has been previously found
for spirals. (2) We obtain median r_{eff}/h_r = 0.20, 0.15 and 0.10 for S0,
S0/a-Sa and Sab-Sc galaxies: these are smaller than predicted by simulation
models in which bulges are formed by galaxy mergers. (3) The properties of
bulges of S0s are different from the elliptical galaxies, which is manifested
in the M_K(bulge) vs r_{eff} relation, in the photometric plane, and to some
extent also in the Kormendy relation. The bulges of S0s are similar to bulges
of spirals with M_K(bulge) < -20 mag. Some S0s have small bulges, but their
properties are not compatible with the idea that they could evolve to dwarfs by
galaxy harassment. (4) The relative bulge flux B/T for S0s covers the full
range found in the Hubble sequence. (5) The values and relations of the
parameters of the disks of the S0 galaxies in NIRS0S are similar to those
obtained for spirals in the OSUBSGS. Overall, our results support the view that
spiral galaxies with bulges brighter than -20 mag in the K-band can evolve
directly into S0s, due to stripping of gas followed by truncated star
formation.
