Near-infrared surface photometry of spiral galaxies. II. Derivation of mass models.

Near-infrared surface photometry of six spiral galaxies is used to separate the main stellar components and derive mass models whose predicted rotation curves are compared to observed gas kinematics. For three of the galaxies, central stellar velocity dispersions are also used. For these intrinsically bright objects, the mass-to-light ratio of the disk, in the K band, is found to be =~1, as expected. In four Sb-Sc galaxies, there is some evidence that the mass-to-light ratio of the bulge may be on average =~20% smaller, but the a priori assumption that these ratios are identical does not significantly bias the disk masses. Early-type spirals with a prominent bulge, in which the apparent central mass-to-light ratio is known to be often low, can need a significant correction to the bulge mass.