  We present Spitzer observations of Tidal Dwarf Galaxies (TDGs) in three
interacting systems: NGC 5291, Arp105 and Stephan's Quintet. The spectra show
bright emission from polyaromatic hydrocarbons (PAHs), nebular lines and warm
molecular hydrogen, characteristic of recent episodes of star formation. The
PAH emission that falls in the IRAC 8.0 micron band leads to the TDGs having an
extremely red IRAC color, with [4.5] - [8.0] > 3. The emission from PAHs is
characterized by a model with mainly neutral 100-C PAH atoms.
