Witnessing gas mixing in the metal distribution of the Hickson Compact
  Group HCG 31
  We present, for the first time, direct evidence that, in a merger of disk
galaxies, the preexisting central metallicities will mix as a result of gas
being transported in the merger interface region, along the line that joins the
two coalescing nuclei. This is shown using detailed 2D kinematics as well as
metallicity measurements for the nearby ongoing merger in the center of the
compact group HCG 31. We focus on the emission line gas, which is extensive in
the system. The two coalescing cores display similar oxygen abundances while in
between the two nuclei the metallicity changes smoothly from one nucleus to the
other, indicating a mix of metals in this region, which is confirmed by the
high resolution H$\alpha$ kinematics (R=45900). This nearby system is
especially important because it involves the merging of two fairly low mass and
clumpy galaxies (LMC-like galaxies), making it an important system for
comparison with high redshift galaxies.
