CONFIRMATION OF FAINT DWARF GALAXIES IN THE M81 GROUP

We have followed up on the results of a 65 deg2 CFHT/MegaCam imaging survey of the nearby M81 Group searching for faint and ultra- faint dwarf galaxies. The original survey turned up 22 faint candidate dwarf members. Based on two- color HST ACS/WFC and WFPC2 photometry, we now confirm 14 of these as dwarf galaxy members of the group. Distances and stellar population characteristics are discussed for each. To a completeness limit of M-r = - 10, we find a galaxy luminosity function slope of - 1.27 +/- 0.04 for the M81 Group. In this region, there are now 36 M81 Group members known, including 4 blue compact dwarfs; 8 other late types including the interacting giants M81, NGC 3077, and M82; 19 early type dwarfs; and at least 5 potential tidal dwarf galaxies. We find that the dSph galaxies in M81 appear to lie in a flattened distribution, similar to that found for the MilkyWay and M31. One of the newly discovered dSph galaxies has properties similar to the ultra- faint dwarfs being found in the Local Group with a size R-e similar to 100 pc and total magnitude estimates M-r = - 6.8 and M-I = - 9.1.