Chemical Abundances of Seven Irregular and Three Tidal Dwarf Galaxies in
  the M81 Group
  We have derived nebular abundances for 10 dwarf galaxies belonging to the M81
Group, including several galaxies which do not have abundances previously
reported in the literature. For each galaxy, multiple H \ii regions were
observed with GMOS-N at the Gemini Observatory in order to determine abundances
of several elements (oxygen, nitrogen, sulfur, neon, and argon). For seven
galaxies, at least one H \ii region had a detection of the temperature
sensitive [OIII] $\lambda$4363 line, allowing a "direct" determination of the
oxygen abundance. No abundance gradients were detected in the targeted galaxies
and the observed oxygen abundances are typically in agreement with the well
known metallicity-luminosity relation. However, three candidate "tidal dwarf"
galaxies lie well off this relation, UGC 5336, Garland, and KDG 61. The nature
of these systems suggests that UGC 5336 and Garland are indeed recently formed
systems, whereas KDG 61 is most likely a dwarf spheroidal galaxy which lies
along the same line of sight as the M81 tidal debris field. We propose that
these H \ii regions formed from previously enriched gas which was stripped from
nearby massive galaxies (e.g., NGC 3077 and M81) during a recent tidal
interaction.
