Star formation in HI tails: HCG 92, HCG 100 and 6 interacting systems
  We present new Gemini spectra of 14 new objects found within the HI tails of
Hickson Compact Groups 92 and 100. Nine of them are GALEX Far-UV (FUV) and
Near-UV (NUV) sources. The spectra confirm that these objects are members of
the compact groups and have metallicities close to solar, with an average value
of 12+log(O/H)~8.5. They have average FUV luminosities 7 x 10^40 erg/s, very
young ages (< 100 Myr) and two of them resemble tidal dwarf galaxies (TDGs)
candidates. We suggest that they were created within gas clouds that were
ejected during galaxy-galaxy interactions into the intergalactic medium, which
would explain the high metallicities of the objects, inherited from the parent
galaxies from which the gas originated. We conduct a search for similar objects
in 6 interacting systems with extended HI tails, NGC 2623, NGC 3079, NGC 3359,
NGC 3627, NGC 3718, NGC 4656. We found 35 UV sources with ages < 100 Myr,
however most of them are on average less luminous/massive than the UV sources
found around HCG 92 and 100. We speculate that this might be an environmental
effect and that compact groups of galaxies are more favorable to TDG formation
than other interacting systems.
