Characterizing Dust Attenuation in Local Star Forming Galaxies:
  Inclination Effects and the 2175\AA\ Feature
  We characterize the influence that inclination has on the shape and
normalization in average dust attenuation curves derived from a sample of
~10,000 local star-forming galaxies. To do this we utilize aperture-matched
multi-wavelength data from the Galaxy Evolution Explorer, the Sloan Digital Sky
Survey, the United Kingdom Infrared Telescope, and the Two Micron All-Sky
Survey. We separate our sample into groups according to axial ratio (b/a) and
obtain an estimate of their average total-to-selective attenuation
$k(\lambda)$. The attenuation curves are found to be shallower at UV
wavelengths with increasing inclination, whereas the shape at longer
wavelengths remains unchanged. The highest inclination subpopulation (b/a<0.42)
exhibits a NUV excess in its average selective attenuation, which, if
interpreted as a 2175\AA\ feature, is best fit with a bump strength of 17-26%
of the MW value. No excess is apparent in the average attenuation curve of
lower inclination galaxies. The differential reddening between the stellar
continuum and ionized gas is found to decrease with increasing inclination. We
find that higher inclination galaxies have slightly higher values of $R_V$,
although this is poorly constrained given the uncertainties. We outline
possible explanations for these trends within a two component dust model (dense
cloud+diffuse dust) and find that they can be naturally explained if carriers
of the 2175\AA\ feature are preferentially destroyed in star-forming regions
(UV-bright regions).
