Stephane Courteau, Queens University, Canada The Mass Distribution, Structure, and Stellar Content of Spiral Galaxies We construct one of the largest data set of global structural parameters of spiral galaxies and explore the joint distribution of luminosity $L$ (in bands $IJK$), maximum circular velocity $V$, and disk scale length $R$. We find a dependence of the velocity- luminosity relation on color, stellar mass-to-light ratio, and star formation history, which are all tightly related. The uncorrelated residuals between the velocity-luminosity and radius-luminosity relations suggest that in most spirals, independent of color, surface brightness and bar size, the dark-matter halo contributes significantly to the potential already at 2.2 disk scale lengths. However, a simultaneous fit to the different constraints may indicate little dark-halo contraction in response to disk formation. The galaxy scaling relations arise naturally from the basic elements of the standard scenario of structure formation: spherical collapse, virial equilibrium and conservation of angular momentum. However, the understanding of features such as color dependence requires a more sophisticated modeling of gaseous disk components, stellar population variations, and angular momentum transfer between disk, bulge and halo. I will also discuss deep Gemini/GMOS spectra of the bulge and disk of a few nearby galaxies in the context of bulge and disk formation models. April 28th at 11am in CFHT conference room