A CFH12K Survey of Red Giant Stars in the M81 Group

Abstract

We present the preliminary results of a wide-field photometric survey of individual red giant branch (RGB) and asymptotic giant branch (AGB) stars in the M81 group, performed with the CFH12K mosaic camera of the CFHT. We use deep VI images of 0.65 sq. deg. of sky to map out the two-dimensional distribution of intragroup stars and to search for stars associated with the many HI tidal tails in the group. We place an upper limit on the presence of metal-poor RGB stars in a field located 50-80 kpc from M81, and derive an ‘intragroup’ fraction of < 2%. In a field sampling the M81-NGC3077 HI tidal tail, we find blue stars associated with some of the tidal features, including 2 clumps which we tentatively describe as tidal dwarf candidates. These objects are ~ 1 kpc in size, and, based on their color-magnitude diagrams, have formed stars as recently as ~ 30 – 70 Myr ago, long after the group's most recent interactions.