This proposal is a crucial part of an on-going program to
 investigate in a self-consistent way the morphological and
 spectrophotometric evolution of ring galaxies. Ring galaxies
 represent the consequence of a close interaction between
 a spiral disk and an intruder, triggering a burst of star
 formation. The result, depending on the parameters of the
 impact, is a more or less sharp ring surrounding an off-centered
 nucleus or an empty region. Substantial advances have been made
 in the last two decades in understanding the complex dynamics
 of galaxy interactions, largely as a result of the efforts
 of numerical experiments. As suggested by our N-body numerical
 simulations, the passage of an intruder through a stellar disk
 generates a transient ring-shaped mass distribution produced by
 a single density wave propagating through the disk. (Curir and
 Filippi, 1994) The efficiency of tidal interactions and merging
 between galaxies in  triggering  star formation is also well
 known since a large fraction of powerful FIR emitters are
 interacting galaxies.
 Ring galaxies are strong FIR sources, some of them also brighter
 than the prototype starburst galaxy M82.
 As suggested by previous works on this subject (Mazzei et al.
 1992, Mazzei et al. 1994, Mazzei and Dezotti, 1994) looking at
 suitable IR spectral ranges we can recover the current value
 as well as the past trend of the star formation rate.
 The observational part of this study on ring galaxies so far
 consist in optical multiband (BVRI) CCD images of a sample of
 objects (Bonoli, 1987). Together with available IRAS data, ISO
 observations will provide a unique clue to further investigate
 the effects of star formation episodes in the MIR and FIR.