Surface Brightness Profiles of Dwarf Galaxies: II. Color Trends and Mass
  Profiles
  In this second paper of a series, we explore the B-V, U-B, and FUV-NUV radial
color trends from a multi-wavelength sample of 141 dwarf disk galaxies. Like
spirals, dwarf galaxies have three types of radial surface brightness profiles:
(I) single exponential throughout the observed extent (the minority), (II)
down-bending (the majority), and (III) up-bending. We find that colors of (1)
Type I dwarfs generally become redder with increasing radius unlike spirals
that have a blueing trend that flattens beyond ~1.5 disk scale lengths, (2)
Type II dwarfs come in six different "flavors," one of which mimics the "U"
shape of spirals, and (3) Type III dwarfs have a stretched "S" shape where
central colors are flattish, become steeply redder to the surface brightness
break, then remain roughly constant beyond, similar to spiral TypeIII color
profiles, but without the central outward bluing. Faint (-9 > M_B > -14) Type
II dwarfs tend to have continuously red or "U" shaped colors and steeper color
slopes than bright (-14 > M_B > -19) Type II dwarfs, which additionally have
colors that become bluer or remain constant with increasing radius. Sm dwarfs
and BCDs tend to have at least some blue and red radial color trend,
respectively. Additionally, we determine stellar surface mass density (Sigma)
profiles and use them to show that the break in Sigma generally remains in Type
II dwarfs (unlike Type II spirals) but generally disappears in Type III dwarfs
(unlike Type III spirals). Moreover, the break in Sigma is strong,
intermediate, and weak in faint dwarfs, bright dwarfs, and spirals,
respectively, indicating that Sigma may straighten with increasing galaxy mass.
Lastly, the average stellar surface mass density at the surface brightness
break is roughly 1-2 M_S/pc^2 for Type II dwarfs but higher at 5.9 M_S/pc^2 or
27 M_S/pc^2 for Type III BCDs and dIms, respectively.
