The Baryonic Tully-Fisher Relation. II.

We outline a range of possible star formation histories and chemical evolution scenarios to explore the confidence limits of stellar population models on the value of U*. We conclude that the greatest uncertainties (around 0.1dex in U*) occur for the bluest galaxies with the strongest variation in recent star formation.

For high-mass galaxies, the greatest uncertainty arises from the proper treatment of bulge-disk separation in which to apply different U* relations appropriate for those differing underlying stellar populations. We compare our deduced stellar masses with those deduced from Spitzer Space Telescope 3.6{mu}m fluxes and stellar mass estimates in the literature using optical photometry and different U* modeling. We find the correspondence to be excellent, arguing that rest-frame near-IR photometry is still more advantageous than other wavelengths.