spiral galaxy which indicates that even if a starburst did occur in it at some point, it has by now subsided and the star formation is progressing in a more quiescent rate.

Finally, we note that the southern galaxy exhibits higher f$_{15\mu
m}$/H$\alpha$ ($\sim$225) compared to that inthe north ($\sim$85). We interpret this effect as a consequence of higher dust concentration and stronger absorption in the southern nucleus since near AGNs high column densitis of molecular gas are typically observed. The southern galaxy also has a higher f$_{15\mu m}$/K ratio than that in the north, which has an f$_{15\mu m}$/K ratio of a normal spiral galaxy,consistent with its overall MIR spectral features (Table \[k\_ha\]).

IRAS23128-5919
--------------

This system consists of two merging galaxies in a rather late stage of their interaction, the nuclei of which are separated by a projected distance of 4 kpc (5) (Figure \[ir23128\_im\]). Two tidal tails 40kpc stretch in opposite directions [@Bergvall1985; @Mihos1998].

Based on optical studies, the northern galaxy is classified as a starburst, while it is unclear whether the southern one is a Seyfert, a starburst or a LINER [@Duc1997a]. Optical spectroscopy of the southern nucleus shows a relatively high ionization state having emission 