A case study for a tidal interaction between dwarf galaxies in UGC 6741
  We present a case study of the tidal interaction between low mass,
star-forming, galaxies initially found exploring the Sloan Digital Sky Survey
(SDSS) images and further analyzed with SDSS spectroscopy and UV GALEX
photometry. With a luminosity of M$_{r}$ = $-$17.7 mag and exhibiting a
prominent tidal filament, UGC 6741 appears as a scale down version of massive
gas--rich interacting systems and mergers.The stellar disk of the smaller
companion, UGC 6741_B, which is three times less massive, has likely been
already destroyed. Both galaxies, which are connected by a 15 kpc long stellar
bridge, have a similar oxygen abundance of 12+log(O/H)$\sim$8.3. Several knots
of star-forming regions are identified along the bridge, some with masses
exceeding $\sim$10$^{7}$ M$_{\sun}$. The most compact of them, which are
unresolved, may evolve into globular clusters or Ultra Compact Dwarf galaxies
(UCDs). This would be the first time progenitors of such objects are detected
in mergers involving dwarf galaxies. UGC 6741 has currently the color and star
formation properties of Blue Compact Dwarf galaxies (BCDs). However the
analysis of its surface photometry suggests that the galaxy lies within the
scaling relations defined by early-type dwarf galaxies (dEs). Thus UGC 6741
appears as a promising system to study the possible transformation of BCDs into
dEs, through possibly a merger episode. The frequency of such dwarf-dwarf
mergers should now be explored.
