and Im respectively. Given their late morphological types we suspect that they contain a significant contribution from a dark component even in their inner regions, although detailed modelling has to be done to check this possibility. Their position in the T-F diagram could, then, be the result of a stripping of this inner dark halo combined with brightening of the galaxy due to star formation (given their blue colors).

A trend of overbright galaxies for their mass was seen, at the low-mass end of the relation, when the T-F diagram of binary galaxies was plotted by Márquez et al. (2002). Three of the least massive galaxies in interacting pairs showed a deviation of the T-F relation in the same sense as observed by us for galaxies in compact groups. Moreover, Kannappan et al. (2002), studying a sample of bright nearby galaxies brighter than M$_R=-18$, noted that interacting galaxies systematically lied above while Sa galaxies fell below the T-F relation. In fact, they proposed that there is a correlation of the residuals of the T-F relation with the star formation history of the galaxy and when a second parameter such as colour or equivalent width of H$\alpha$ is taken into account, 