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L.E. Kuchinski, B.F. Madore (IPAC, Caltech/JPL), W. L. Freedman (OCIW), M. N. Fanelli (NASA/GSFC), P.M. Marcum (TCU), R.W. O'Connell (UVA), T.P. Stecher (NASA/GSFC)
We present far-ultraviolet (FUV) and optical (UBVI) images and surface brightness profiles of several nearby spiral galaxies and discuss wavelength-dependent changes in their apparent morphology both qualitatively and quantitatively. This subset of the UIT Astro-2 sample contains Hubble types Sa-Im and was selected to emphasize late-type systems in which star formation produces prominent morphological features in the FUV (~1600Å). Spiral arms, rings, and circumnuclear star formation regions are clearly evident in comparisons of the FUV and optical images and dominate the azimuthally averaged FUV surface brightness and FUV-optical color profiles. The strong deviations from a smooth disk or disk+bulge profile that are seen in the FUV highlight the difficulty of determining traditional disk and bulge structural parameters from rest-frame UV galaxy images. We also calculate concentration and asymmetry indices for the sample galaxies in the FUV and UBVI bandpasses to investigate trends with wavelength. Measurements of these indices at ultraviolet as well as optical wavelengths will help quantify the ``morphological k-correction'' out to high redshift without the need to simulate band-shifting. Based on characteristics observed in the FUV galaxy images, we discuss some requirements for a classification scheme that would be applicable to rest-frame UV galaxy images, mergers and protogalaxies, and other situations in which the Hubble system does not adequately describe the observed morphology.