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J. E. Cabanela (Saint Cloud State University), S. K. Sidhu (Swarthmore College), W. J. Bennett (Drake University)
We report on our continuing efforts to quantify the internal extinction of light due to interstellar dust within spiral galaxies. Our technique is to assemble a large ensemble of spiral galaxies with accurate measures of their luminosity (L), isophotal diameter (D), and mean surface brightness (\mu) and then statistically evaluate how those three properties vary with galaxy inclination. An accurate model for the distribution of interstellar dust in spirals is critical to proper insight on their intrinsic properties. Most studies of distribution of dust in galaxies have been limited to relatively small samples of spirals or large samples with ill-determined optical parameters. Consequently, the distribution of dust in spirals is not well understood, and knowing how L, D, and \mu vary as a function of inclination is a useful tool for discriminating among the existing models for the distribution of dust in spirals.
We have a sample of over 70000 galaxies from the Sloan Digital Sky Survey Data Release Three (SDSS DR3), selected on the basis on their major-axis angular diameter (ar > 15{\arcsec}), their exponential surface brightness profiles, and their redshift (0.01 < z < 0.20). These spiral galaxies are sorted into magnitude and diameter-limited subsets and for each subset the changes in L, D, and \mu with varying inclination were modeled in all five bandpasses for which data was available. The project is ongoing with students working on the outstanding issues of photometric idiosyncrasies of the SDSS and the development of a more accurate morphological classification of the sample galaxies.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.