Kinematics and composition of H II regions in spiral galaxies. I. M33

Moderate-dispersion, 0l.7 A/pixel spectra of H II regions in M33 were taken, and the velocity as well as the excitation were measured by observing the spectral region around H-beta. Velocity measurements for 55 H II regions and excitation measurements for 42 regions are presented. The velocity data are used to measure the systemic velocity at -172 + or - 6 km/s, the inclination at 56 + or - 1 deg, the position angle of the major axis at 23 + or - 1 deg, the rotation curve of the H II regions, and their line-of-sight velocity dispersion at 9 + or - 4 km/s. These data are used to derive the M/L ratio from radii of 0.5-3.7 kpc. The excitation measurements are used to derive a metallicity gradient for M33 and to quantify the dispersion in the excitation values at a given radius. 52 references