MAJOR MERGERS with SMALL GALAXIES: The DISCOVERY of A MAGELLANIC-TYPE GALAXY at z = 0.12

Abstract

We report on the serendipitous discovery of a star-forming galaxy at redshift z = 0.116 with morphological features that indicate an ongoing merger. This object exhibits two clearly separated components with significantly different colors, plus a possible tidal stream. Follow-up spectroscopy of the bluer component revealed a low star-forming activity of 0.09 Mo yr-1 and a high metallicity of 12 + log(O/H) = 8.6. Based on comparison with mass-star formation-rate and mass-metallicity relations, and on fitting of spectral energy distributions, we obtain a stellar mass of 3 109 Mo, which renders this object comparable to the Large Magellanic Cloud. Thus our finding provides a further piece of evidence of a major merger already acting on small, dwarf-galaxy-like scales.