Stellar and gas kinematics in disk galaxies.

Extended absorption- and emission-line rotation curves and stellar velocity dispersion curves have been obtained for NGC 3898 (Sab), NGC 2841 (Sb), NGC 4062 (Sc), and NGC 2998 (Sc), along with a few observations of NGC 3200 (Sab) and M82 (I). These have been combined with additional observations by Kormendy and Illingworth (1982) to establish the following results. In the disk, the rotation of the gas and stellar components are similar. In the bulge, stellar rotational velocities are only about half of the rotation of the disk. The velocity dispersion curves exhibit a decline with radius, with the small bulge systems showing the steepest decline. A reevaluation of the V(bulge)/sigma(0)-versus-ellipticity diagram for spiral bulges shows that models of rotationally flattened oblate spheroids do not fully explain the observations. As part of this analysis, numerical experiments have been performed to determine values of the intrinsic rotation of the bulge in regions where significant fractions of the light come from both the bulge and the disk. These mixing experiments show that differences in both line strengths and velocity dispersions play major roles in producing the observed velocities.