A panoramic view of M81: New stellar systems in the debris field
  Using the MegaCam imager on the Canada-France-Hawaii Telescope, we have
resolved individual stars in the outskirts of the nearby large spiral galaxy
M81 (NGC 3031) well below the tip of the red giant branch of metal-poor stellar
populations over 60 kpc * 58 kpc. In this paper, we report the discovery of new
young stellar systems in the outskirts of M81. The most prominent feature is a
chain of clumps of young stars distributed along the extended southern HI tidal
arm connecting M 81 and NGC 3077. The colour-magnitude diagrams of these
stellar systems show plumes of bright main sequence stars and red supergiant
stars, indicating extended events of star formation. The main sequence
turn-offs of the youngest stars in the systems are consistent with ages of ~40
Myr. The newly reported stellar systems show strong similarities with other
known young stellar systems in the debris field around M81, with their
properties best explained by these systems being of tidal origin.
