A spatially resolved study of ionized regions in galaxies at different ...

3.5. Discussion 103
0.6
0.4
log([NII]/[SII])
0.2
A
B C D
0.0
−0.2
−0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2
log ([OII]/[OIII])
0.6
0.4
log(S23)
0.2
0.0
A
B C D
−0.2
−0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2
log ([OII]/[OIII])
Figure 3.29: Point-to-point variations of the line ratio [Nii]/[Sii] (upper) and S 23 parameter (lower)
versus the excitation measured as [Oii]/[Oiii]. The (red) circle points represents the integrated values
of the knots, while the (yellow) square point the position in the diagram of the whole PPak field.
observed line ratios [Nii] λλ 6585,6584/[Sii] λλ 6717,6731 and the S 23 parameter as a function
of the degree of excitation measured by [Oii]/[Oiii]. All values were obtained from the first
pointing set, since the quantities represented involve the infrared sulphur lines. Although the
first ratio contains only lines present in the blue part of the spectra, we have decided to use
for this ratio only the first dithering instead of the mosaic for consistency in the comparison.
In this case, for each point, the accuracy of the ratios is typically better than 20 percent.
The ratio [Nii] λλ 6585,6584/[Sii] λλ 6717,6731 versus the excitation seems fairly constant,
although it can be appreciated a slight relative decrease with [Oii]/[Oiii]. This effect was also