The Baryonic Tully-fisher Relation of Galaxies with Extended Rotation Curves and the Stellar Mass of Rotating Galaxies

I investigate the Baryonic Tully-Fisher relation for a sample of galaxies with extended 21 cm rotation curves spanning the range 20 . Vf ≤ 300 kms . A variety of scalings of the stellar mass-to-light ratio Υ⋆ are considered. For each prescription for Υ⋆, I give fits of the form Md = AV x f . Presumably, the prescription that comes closest to the correct value will minimize the scatter in the relation. The fit with minimum scatter has A = 50M⊙ km −4 s and x = 4. This relation holds over five decades in mass. Galaxy color, stellar fraction, and Υ⋆ are correlated with each other and with Md, in the sense that more massive galaxies tend to be more evolved. There is a systematic dependence of the degree of maximality of disks on surface brightness. High surface brightness galaxies typically have Υ⋆ ∼ 3 4 of the maximum disk value, while low surface brightness galaxies typically attain ∼ 14 of this amount. Subject headings: dark matter — galaxies: kinematics and dynamics — galaxies: spiral