Two-dimensional Kinematics of Spiral Galaxies and the \\Maximum Disk Hypothesis
Session 77 -- Spirals II
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[77.18] Two-dimensional Kinematics of Spiral Galaxies and the \\Maximum Disk Hypothesis

P. Palunas, T.B. Williams (Rutgers University)

\def\kms{$\rm {km}~\rm s^{-1}$}

We present an analysis of two-dimensional H$\alpha$ velocity maps and\\ $I$-band surface photometry for a sample of galaxies taken from the southern sky Fabry-Perot Tully-Fisher survey (Schommer et al., 1993, AJ 105, 97). We examine the detailed azimuthal variations in the kinematics and surface brightness of these galaxies.

Mass models for spiral galaxies in many cases reveal a correlation between bumps and wiggles'' in the photometric profile and the rotation curve. This is often taken as further evidence for the maximum disk model in which the halo mass is minimized within the optical radius. However, rotation curves derived from single slit observations sample the velocity distribution only along the major-axis; and photometric profiles for inclined galaxies are sampled most heavily near the major-axis. The bumps and wiggles'' correlation may therefore be due to local perturbations rather than the global mass distribution, thus weakening this argument for the maximum disk hypothesis. These local perturbations may be due to spiral arms and spiral arm streaming motions. Two arm spirals would show the same effect on both sides of the galaxy. We analyse the two-dimensional surface brightness and velocity distributions to determine the possible influence of this effect. We also measure the magnitude of non-circular motions caused by spiral arms.