Program: GN-2013A-Q-87

Tidal debris caused by interactions and mergers systems may be ideal laboratories to study galaxy formation. These interacting systems are excellent candidates to contain a large number of HII-regions outside the member galaxies and Tidal Dwarf Galaxies (TDG) and we have verified that with our results so far. We have searched for young-stellar complexes in different systems with optical and/or gaseous tidal tails, all of them with available GALEX/UV and HI images from the archive. One of these systems is NGC4656/7, where we detected (in GALEX images) a candidate TDG to the north of the main system, which overlaps with the maximum density contours of HI gas, with a faint optical counterpart. Several HII-regions can be observed inside the TDG. Gemini/GMOS data of this TDG will be useful to determine the ages, oxygen abundance and radial velocities of each star-forming complex. This information will be used to determine metallicity gradient and the velocity field in this system, and measure if it has ordered motion or not. With GALEX analysis we identified about 12 UV-sources in the tidal tails of the system, where 8 regions present age < 15Myr. If this proposal is successful, we plan to now obtain GMOS spectra of the sources to derive their velocities and metallicities. If we find high metallicities we will have that these IGM objects are newly formed in tidal debris and this process is wide spread in interacting/merging systems. This is the main part of the Ph.D.-Thesis of Fernanda Urrutia-V.