The extrapolated central surface brightness vs. exponential scale length

In Figs. and are plotted the relations between the central extrapolated exponential surface brightness 41#41 and the logarithm of the exponential scale-length 141#141 for all galaxies, early types and late types respectively. The dashed lines are lines of constant magnitude at 214#214 (lower) and 53#53 (upper), for a pure exponential surface brightness profile. The data are coded into group&field and cluster samples like in the previous sections, but additionally the data are separated into magnitude bins. The coding scheme is: open symbols for the cluster samples, and filled symbols for the group&field sample. The symbols represent the magnitude bins the galaxies fall into, i.e. circles, triangles, squares, and inverted triangles for the four one-magnitude wide bins between 143#143 to 215#215. Crosses represent group&field galaxies outside this magnitude range, and plus signs represent the equivalent cluster data points.

Figure: Plot of 141#141 versus 41#41 for the whole samples. The symbols are described in the text. Lines of constant total magnitude are drawn. The upper line is at 217#217, whereas the lower line is at 218#218 10#10 magnitudes. Filled symbols represent group&field galaxies, and the different symbol types represent the four one-magnitude bins from 219#219 to 220#220. Crosses and plus signs represent group&field and cluster galaxies outside this magnitude range, respectively.

216#216

Figure: Plot of 141#141 versus 41#41 for the early type galaxies (left) snd late types (right). Lines of constant total magnitude are drawn. The upper line is at 217#217, whereas the lower line is at 218#218 10#10 magnitudes. The symbols are as in Fig. .

221#221

Some of the group&field galaxies tend to scatter perpendicularly to the constant magnitude lines. This scatter is somewhat larger than that of cluster galaxies, indicating larger deviations from pure exponentials in the former environment. But on the average, the group&field sample populates a region of smaller scale length and brighter central surface brightness. The tendency is much more pronounced in the case of early type galaxies, as was noted in the previous sections. Also, one again sees the trend defined by the early type galaxies: they tend to have smaller sizes and higher surface brightnesses than their cluster counterparts, at faint absolute magnitudes. The same parameters are rather similar between group&field and cluster galaxies for the galaxies at bright end of the analysis range.