EFFECTS OF INTERACTIONS ON THE NUCLEAR NEAR-INFRARED PROPERTIES OF SPIRAL GALAXIES

Using JHKL photometric measures available in the literature, we have c ompared the near-infrared colour indices and central luminosities of s amples of relatively isolated spiral galaxies with LINER and H II regi on-like nuclei (hereafter called L and H) with corresponding samples o f interacting galaxies, in order to explore the effects of interaction s on their near-infrared properties. We have found that the L galaxies and the isolated H galaxies have, in general, normal near-infrared co lours which are fully explainable in terms of emission from latetype e volved stars. On the other hand, the sample of interacting H galaxies displays, on average, somewhat peculiar near-infrared colours (specifi cally, normal J - H colours, but redward H - K and, especially, K - L excesses), which very probably indicate the presence of thermal emissi on from hot dust, presumably related to intense star formation activit y induced by the interactions. Furthermore, for the same galaxy sample there is some evidence that the emission at lambda approximately 2.2 mum is somewhat more centrally concentrated than that at shorter wavel engths. Interestingly, the L galaxies appear to have greater central n ear-infrared luminosities than the H galaxies, for the same morphologi cal-type interval.