Star-forming regions and the metallicity gradients in the tidal tails:
  The case of NGC 92
  We present new Gemini/GMOS spectroscopic and archival imaging data of the
interacting galaxy NGC 92, which is part of a compact group and displays an
extended tidal tail. We have studied the physical properties of 20 star-forming
complexes in this system. We found that the star-forming regions located in the
tidal tail of NGC 92 have ages younger than 8 Myr, which suggests that these
objects were formed in situ. The spectroscopic data reveals that these regions
have slightly sub-solar metallicities, suggesting that they were formed from
pre-enriched material. Using the oxygen abundances derived for each system, we
found that the extended tidal tail of NGC 92 has a flat metallicity
distribution. Although this scenario is consistent with N-body simulations of
interacting systems, where there is gas mixing triggered by the interaction,
archival Halpha Fabry-Perot data cubes of NGC 92 have not shown a velocity
gradient along the tail of this galaxy, which under certain assumptions could
be interpreted as a lack of gas flow in the tail. Our results suggest that a
fraction of the enriched gas that was originally located in the center of the
galaxy was expelled into the tidal tail when the interacting process that
formed the tail happened. However, we can not exclude the scenario in which the
star formation in the tail has increased its original oxygen abundance.
