Structural analysis has been performed for a sample of 15 Southern early-type disk galaxies , mainly S0s , using high resolution K _ { s } -band images .
The galaxies are mostly barred and many of them show multiple structures including bars and ovals , typical for S0s .
The new images are of sufficient quality to reveal new detail on the morphology of the galaxies .
For example , we report a hitherto undetected nuclear ring in NGC 1387 , a nuclear bar in NGC 1326 , and in the residual image also a weak primary bar in NGC 1317 .
For the galaxies we ( 1 ) measure the radial profiles of the orientation parameters derived from the elliptical isophotes , ( 2 ) apply Fourier methods for calculating tangential forces , and particularly , ( 3 ) apply structural decomposition methods .
For galaxies with multiple structures a 2-dimensional method is found to be superior to a 1-dimensional method , but only if in addition to the bulge and the disk , at least one other component is taken into account . We find strong evidence of pseudo-bulges in S0s : ten of the galaxies have the shape parameter of the bulge near to n = 2 , indicating that the bulges are more disk-like than following the R ^ { 1 / 4 } -law .
Also , six of the galaxies have either nuclear rings , nuclear bars or nuclear disks .
In all non-elliptical galaxies in our sample the B / T < 0.4 , as typically found in galaxies having pseudo-bulges . In two of the galaxies the B / T flux ratio is as small as in typical Sc-type spirals .
This might be the hitherto undiscovered link in the scenario in which spirals are transformed into S0s . Also , bars in S0s are found to be shorter and less massive , and have smaller bar torques than bars in S0/a-type galaxies .