We propose to obtain 6.7 and 15 microns ISOCAM and 90 microns ISOPHOT
observations of a sample of 5-6 compact groups of galaxies selected for
their diffuse X-ray emission. The presence of X-ray emission insures
the real physical association of these compact groups. We also include
one compact group without X-ray emission, for comparison.

Because of their density and compactness, these compact groups are
priviledged laboratories for studying dynamical interactions such as
merging and tidal encounters that can produce IR emission. These CGs
possess comprehensive multi-wavelength studies including substantial
X-ray data which will complement the proposed IR observation.

ISOCAM with its superior sensitivity and spatial resolution as compared
to IRAS will allow us to better study the MIR properties of CG
galaxies, while ISOPHOT will allow to measure (or put constraints) on
both the FIR emission from the galaxies and from the intra-group
medium. With these two types of observations, we can study the star
formation in the galaxies of the groups. Diffuse FIR emission as well
as the iron abundance in the intra-group medium are indicators of the
past star formation activity while the MIR and FIR emission of the
galaxies probe present star formation.

The IR properties of CG galaxies can be compared with those of field
and cluster galaxies to determine the effect of environment on galaxy
evolution.