The Stellar Disk of M81
  Wide-field images obtained with the 3.6 meter Canada-France-Hawaii Telescope
are used to investigate the spatial distribution and photometric properties of
the brightest stars in the disk of M81 (NGC 3031). With the exception of the
central regions of the galaxy and gaps between CCDs, the survey is spatially
complete for stars with i' < 24 and major axis distances of 18 kpc. A more
modest near-infrared survey detects stars with K < 20 over roughly one third of
the disk. Bright main sequence (MS) stars and RSGs are traced out to
galactocentric distances of at least 18 kpc. The spatial distribution of bright
MS stars tracks emission at far-ultraviolet, mid- and far-infrared wavelengths,
although tidal features contain bright MS stars but have little or no infrared
flux. The specific frequency of bright MS stars and RSGs, normalized to K-band
integrated brightness, increases with radius, indicating that during the past
30 Myr the specific star formation rate (SSFR) has increased with increasing
radius. The stellar content of the M81 disk undergoes a distinct change near R
~ 14 kpc, and the luminosity-weighted mean age decreases with increasing radius
in the outer regions of the M81 disk.
