The "Super-Halo" of M31 and M33
  Two recent observations regarding the halo of M33 seem to contradict each other. First, the star clusters in the halo of M33 exhibit an age range of 5 to 7 Gyr suggesting a formation scenario that involves the chaotic fragmentation and accretion of dwarf satellites. In contrast, deep photometric searches for the resultant tidal tails and stellar streams in the vicinity of M33 have turned up nothing significant. In this contribution, we have tried to reconcile these apparently disparate observations. We suggest that M33 is situated within a 'superhalo' which contains many other dwarf spheroidal and dwarf irregular galaxies that are satellites of M31. In such a scenario, the tidal field of M31 could have disrupted and/or diluted the leftover tails and streams leaving little to be detected in the present day. 
Ata Sarajedini (University of Florida)